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S

Israel Atomic Energy Commission

IA-1421


AVAILABILITY

Israel Atomic Energy Commission reports

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Technical Information Department


P.O.Box 7061, 61 070 Tel-Aviv, ISRAEL

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CONTENTS

MATHEMATICS, THEORETICAL PHYSICS AND THEORETICAL CHEMISTRY

NUCLEAR ENGINEERING AND SAFETY

PLASMA PHYSICS AND PLASMA CHEMISTRY

LASERS AND ATMOSPHERIC OPTICS

SOLID STATE PHYSICS AND CHEMISTRY

MATERIALS SCIENCE

NUCLEAR PHYSICS

GENERAL, PHYSICAL AND RADIATION CHEMISTRY

RADIOISOTOPES. LABELED COMPOUNDS AND BIOSCIENCES

NUCLEAR SAFETY, RADIATION PROTECTION AND ENVIRONMENTAL STUDIES

INSTRUMENTATION AND TECHNIQUES

DOCUMENTATION

AUTHOR INDEX

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61

75

109

115

141

171

187

209

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The s tud ies connected with nuclear power p lan ts are performed in cooperation and c o o r d i n a t i o n with the M in i s t r y of Energy and Infrastructure which has ministerial responsibility in th is f ield.

FOREWORD

The Annual Report of the I s r a e l Atomic Energy Commission presents , as in pas t y e a r s , a resume of the s c i e n t i f i c r e s e a r c h c a r r i e d out by t h e s taf f of i t s nuclear research centers . The main thrus t continues to be twof o l d : a long range , s u s t a i n e d e f f o r t in ba s i c R&D and dynamic growth in the appl ica t ion of nuclear science and technology to securing benef i ts in various spheres of economic a c t i v i t y .

Some examples of these a c t i v i t i e s include: - Development of a water permeable p l a s t i c membrane produced by a radiation*-1

induced g r a f t i n g p rocess to r e p l a c e human or animal sk in g r a f t s used in the treatment of severe burns.

- Development of new t y p e s of r a d i o p h a r m a c e u t i c a l s based on s h o r t - l i v e d isotopes (e.g. an O s / I r g e n e r a t o r ) .

* Development of c o n t r a s t agents for medical n u c l e a r magnetic resonance imaging.

n Deve lopment of r a d i a t i o n s t e r i l i z a t i o n of c u l t u r e media f o r bac te r io log ica l t e s t i n g in medicine and in the food industry.

« Development of procedures for the r a d i a t i o n t r ea tmen t of f r u i t s , vegetables and spices .

- Development of ion i m p l a n t a t i o n t echn iques for surface modification of metals.

- Comprehensive c h a r a c t e r i z a t i o n of o p t i c a l components, i .e . windows, lenses, mirrors, wedges, prisms, laser rods and curvature of focal length.

In the f i e l d of minera l p r o s p e c t i n g and r e c o v e r y , a s ea rch for uranium resources throughout I s r a e l was carr ied out. Novel processes for r e c o v e r y of uranium from phospha tes , a s a by-product of the p roduc t ion of phosphoric acid, were developed. These processes can provide uranium a t a p r i c e which i s c o m p e t i t i v e with the p r e s e n t p r i c e of uranium on the in t e rna t iona l market.

The knowledge and exper t i se gained in these endeavors strengthens the I s r a e l i s c i en t i f i c and indus t r i a l in f ras t ruc ture . Within t h i s context, i t i s bel ieved that the in te rac t ion between the research centers and industry w i l l be mutually benef i c i a l . To t h i s end, s u i t a b l e indus t r i a l parks are now being s e t up.

In the f i e l d of nuclear power p lan t s , the scope of a c t i v i t i e s r e l a t e d to Light Water Reactors for power generation has been narrowed. I s r ae l i s c o n s i d e r i n g what may be termed a s h i f t towards more emphasis on R & D and conceptual design of the coming generation of nuclear power reac tors .

Tel Aviv David Peleg (j June 1986 Acting Director General

IAEC

HIGH DENSITY PROPERTIES OF INTEGRAL EQUATION THEORIES OF FLUIDS: UNIVERSAL ANALYTIC STRUCTURE AND DETAILS FOR THE ONE-COMPONENT PLASMA [1 f 2 ] Y. Rosenfeld

We s t u d i e d t h e a n a l y t i c p r o p e r t i e s of t h e h y p e r n e t t e d c h a i n (HNC) and s o f t - m e a n - s p h e r i c a l (SMSA) t h e o r i e s i n t h e a s y m p t o t i c h i g h d e n s i t y l i m i t (AHDL). The s c a l i n g p r o p e r t i e s of the i n v e r s e power p o t e n t i a l s l ead t o the i n t r o d u c t i o n of the SMSA-Ewald f u n c t i o n s , which correspond t o t he " o v e r l a p - v o l u m e " f u n c t i o n s for hard sphe re s . The HNC and SMSA t h e o r i e s for s o f t i n t e r a c t i o n s , a s w e l l a s t h e P e r c u s - Y e v i c k t h e o r y f o r h a r d s p h e r e s (FYHS), f e a t u r e t h e same AHDL a n a l y t i c s t r u c t u r e of t h e p a i r c o r r e l a t i o n f u n c t i o n s , which i s d i c t a t e d by the h a r d - s p h e r e Ewald func t ions . D e t a i l e d r e s u l t s for the one-component plasma were a l s o ob ta ined . I m p l i c a t i o n s for t h e a n a l y s i s of t h e d e n s i t y f u n c t i o n a l t h e o r y , of d e n s e m a t t e r , n e a r i t s exac t Thomas-Fermi l i m i t were po in t ed o u t . REFERENCES:

[ 1 ] Rosenfe ld , Y. , Phys . Rev. A 3 2 , 183^ (1985) . [ 2 ] Rosenfe ld , Y. , Phys . Rev. A 3 3 , 2025 (1986) .

STATISTICAL THERMODYNAMICS OF CHARGED OBJECTS: GENERAL METHOD AND APPLICATIONS TO SIMPLE SYSTEMS*

Y. Rosenfeld and L. Blum Real f l u i d s are composed of m o l e c u l e s t h a t a r e o b j e c t s of complex

geomet r ies and charge d i s t r i b u t i o n s . In a p r e v i o u s no te [1 ] we have shown t h a t by s t u d y i n g t h e a s y m p t o t i c h i g h d e n s i t y l i m i t (AHDL) and t h e asympto t ic s t r o n g c o u p l i n g l i m i t (ASCL) one i s a b l e t o reduce t h e problem of computing the thermodynamics and c o r r e l a t i o n f u n c t i o n s of t he system to a geomet r i ca l c a l c u l a t i o n i n v o l v i n g ove r l ap i n t e g r a l s between the o b j e c t s .

In p r e v i o u s work [2 ,3 ] a s imp le g e o m e t r i c a l , p h y s i c a l l y i n t u i t i v e meaning of t h e d i r e c t c o r r e l a t i o n f u n c t i o n s (dc f ) f o r p o i n t c h a r g e s i n a background (2,43 (as i n t e r a c t i o n s between smeared charges) and hard s p h e r e s ( a s o v e r l a p v o l u m e s ) w i t h i n t h e mean s p h e r i c a l a p p r o x i m a t i o n (MSA) was g i v e n , t h u s a l s o r e v e a l i n g the a n a l y t i c s t r u c t u r e of the s o l u t i o n to the model e q u a t i o n s . As a r e s u l t , t h e a b o v e c a l c u l a t i o n can be c a r r i e d ou t c o m p l e t e l y for r e l a t i v e l y s imple systems (as e.g. t he g e n e r a l i o n i c mix ture of t he mult icomponent plasmas [ 4 , 5 ] u s ing the MSA f r ee energy f u n c t i o n a l wh ich i n t e r p o l a t e s be tween t h e e x a c t weak- ( D e b y e - H u c k e l ) and s t r o n g -( " O n s a g e r - t y p e " ) c o u p l i n g bounds f o r t h e p o t e n t i a l e n e r g y . Though f e a t u r i n g fewer " i d e a l i s t i c " f e a t u r e s , in view of the h igher complex i ty of t h e p r o b l e m , t h i s a p p r o a c h was s u c c e s s f u l l y u sed t o a n a l y z e t h e " i s o t r o p i c " - " n e m a t i c " t r a n s i t i o n of l i n e - c h a r g e s [ 3 , 6 ] and the c o u p l i n g of

+ T h i s work was s u p p o r t e d i n p a r t by PRF 15473 and t h e O f f i c e of N a v a l Research U n i v e r s i t y of Pue r to Rico, Rio P i e d r a s , P u e r t o Rico, U.S.A.

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the growth of micelles to their degree of alignment [6], In the present work we extended these methods to a much larger class of objects.

The proposed approach is to write down an approximate free energy functional which has to be variational with respect to the pair functions. These would be either the indirect (hi-id"!?)) o r d i r e c t ( c i i ( r i ? ^ c o r r e l a t i o n f u n c t i o n s . I n order t o ge t a conven ien t formalism, we have t o use s imple f u n c t i o n s w i t h p h y s i c a l l y m o t i v a t e d c o e f f i c i e n t s . Indeed, t h e d i r e c t c o r r e l a t i o n f u n c t i o n i n t h e a s y m p t o t i c l i m i t s (AL = e i t h e r AHDL, ASCL) p rov ides such a simple i n s t r u c t i v e b a s i s .

The a p p r o x i m a t e s o l u t i o n s a l s o p r o v i d e e x a c t bounds f o r t h e f r e e energy of sys tem. In the p r e s e n t work we cons idered a few simple sy s t ems . REFERENCES: [ 1 ] R o s e n f e l d , Y. and Blum, L., J . P h y s . Chem. 819_, 5119 (1985) . [2] Rosenfeld, Y., Phys . Rev. A 32, 1834 (1985) . [3] Rosenfeld, Y. and G e l b a r t , W. M., J . Chem. Phys. 8l_, 4574 (1981) . [4] Rosenfeld, Y., Phys . Rev. A 25 , 1206 (1982) . [5] Rosenfeld, Y., Phys. Rev. A 26 , 3622 (1982) . [6] McMul l en , W. E., R o s e n f e l d , Y. and G e l b a r t , W. M., J . Chem. P h y s . , i n

p r e s s .

IMPROVED REGULA FALSI METHOD FOR SOLVING THE SCHRODINGER EQUATION WITH A PIECEWISE CONSTANT POTENTIAL

M. Friedman and A. Rabinovi tch The s o l u t i o n of the 1-D Schrodinger equa t ion i s of major importance

in quantum m e c h a n i c s [ 1 ] . Many 3~D s y s t e m s can be r e d u c e d t o 1-D by s t anda rd t e c h n i q u e s , such a s the s e p a r a t i o n of v a r i a b l e s . Moreover, quas i 1-D s y s t e m s h a v e r e c e n t l y a t t r a c t e d c o n s i d e r a b l e a t t e n t i o n [ 2 ] ; l o c a l i z a t i o n problems and t u n n e l l i n g a r e t r e a t e d mainly i n 1-D d i s o r d e r e d l a t t i c e s [ 3 ] . Since the number of c a s e s for which a n a l y t i c s o l u t i o n s a r e a v a i l a b l e i s r a t h e r s m a l l , a g e n e r a l n u m e r i c a l scheme c o u l d be v e r y h e l p f u l . A s i m p l e a p p r o a c h i s t o r e p l a c e t he p o t e n t i a l V(x) of t h e S c h r o d i n g e r e q u a t i o n by a p i e c e w i s e c o n s t a n t f u n c t i o n f o r which t h e s o l u t i o n i s o b t a i n e d by m e r g i n g t o g e t h e r t h e known s o l u t i o n s of each i n t e r v a l . In a d d i t i o n t o b e i n g an a p p r o x i m a t i o n t o t h e g e n e r a l c a s e , i t can s i m p l y y i e l d t h e main q u a l i t a t i v e f e a t u r e s of any p r o b l e m . I n p a r t i c u l a r , i f the a c t u a l p o t e n t i a l i s unknown but for i t s g e n e r a l form, the use of a s tepped p o t e n t i a l [4] b r i n g s out the r e l e v a n t p r o p e r t i e s of the problem and permi t s unde r s t and ing i t s p h y s i c a l n a t u r e .

A n u m e r i c a l p r o c e d u r e d e s i g n e d t o g e t t h e e i g e n v a l u e s of t h e piecewise c o n s t a n t Schrodinger equa t ion was o u t l i n e d . Since i t c a l l s for the computat ion of the ze roes of a compl i ca t ed funct ion , s p e c i a l a t t e n t i o n was g iven t o r educ ing computing c o s t s . A new improved r e g u l a f a l s i method was used . Only one c a l c u l a t i o n of t h e f u n c t i o n pe r s t e p i s n e e d e d , b u t a

Ben-Gurion U n i v e r s i t y of the Negev, Beer-Sheva

H

q u a d r a t i c c o n v e r g e n c e f o r t h e s e c o n d and t h i r d i t e r a t i o n s i s s t i l l guaran teed . REFERENCES: [1] s e e e .g . , M a t t i s , E. H. and M a t t i s , D. C., M a t h e m a t i c a l P h y s i c s i n One

Dimension, Academic P r e s s , New York, 1966. [2] B e r n a s c o n i , J . and S c h n e i d e r , T., e d i t o r s , P h y s i c s i n one Dimens ion ,

S p r i n g e r - V e r l a g , B e r l i n , 1981, p. 227 ff. [3] E r d o s , P. E. and Hendon, R. C , Adv. P h y s . 3X, 65 (1982) . [H] s e e e .g . , R o s e n f e l d , Y. and T h i e b e r g e r , R., J . Chem. P h y s . 6j3, 1875

(1975) .

ON THE CONVERGENCE OF THE TROTTER FORMULA [1] R. Thieberger

I n r e c e n t y e a r s t h e r e has been much i n t e r e s t i n s o l v i n g quantum s t a t i s t i c a l m e c h a n i c s p r o b l e m s by a M o n t e - C a r l o p r o c e d u r e [ 2 ] , The a p p r o a c h i s ba sed on t h e p a t h i n t e g r a l f o r m u l a t i o n due t o Feynman. I n t i m a t e l y connected to t h i s approach i s the T r o t t e r product formula [ 3 ] . L i t t l e i s known a b o u t t h e n a t u r e of t h i s f o r m u l a . I n t h i s work t h e c o n v e r g e n c e of t h e T r o t t e r f o r m u l a f o r t h e o n e - d i m e n s i o n a l h a r m o n i c o s c i l l a t o r was s tud ied . Pade approximants improve the convergence. REFERENCES: [1] Th iebe rge r , R., J . Phys . A, in p r e s s . [2] See e.g. De R a e d t , H., L a g e n d i j k , A. and F i v e s , J . , Z. P h y s . B £ 6 , 261

(1982) . [3D Suzuki , M. , Commun. Math. Phys . 51_, 183 (1976) .

THREE-DIMENSIONAL EFFECTIVE PHASESHIFTS IN THE PRESENCE OF ELECTRIC FIELDS [1 ] K. Th iebe rge r , M. Friedman and A. Rabinovi tch*

A p r e v i o u s l y d e v e l o p e d s c a t t e r i n g t h e o r y method fo r o n e -d i m e n s i o n a l p r o b l e m s [ 2 ] was g e n e r a l i z e d to t r e a t t h r e e d imens ional problems. The method pe rmi t s c a l c u l a t i n g e f f e c t i v e phase s h i f t s in the presence of an e l e c t r i c f i e l d . A t h r e e - d i m e n s i o n a l scheme i s needed for t he e x p e r i m e n t a l l y important problem of the S ta rk e f f e c t in atoms, e s p e c i a l l y for those which a r e not hydrogenic or h y d r o g e n i c - l i k e . A n u m e r i c a l c a l c u l a t i o n was p e r f o r m e d , a s an e x a m p l e , for a s c r e e n e d Coulomb p o t e n t i a l .

REFERENCES: [1 ] T h i e b e r g e r , R., F r i e d m a n , M. and R a b i n o v i t c h , A., J . P h y s . B J_8, L673

(1985) . [2] R a b i n o v i t c h , A., T h i e b e r g e r , R. and F r i edman , M., J . Phys . B J_8, 393

(1985) .

Ben-Gurion Un ive r s i ty of the Negev, Beer-Sheva

5

ISING MODEL ON A QUASIPERIODIC CHAIN"*" [ 1 ]

Y. Aohiam, T. C. Lubensky and E. W. Marsha l l The t he rmodynamic p r o p e r t i e s of a s p i n s y s t e m w i t h two d i f f e r e n t

n e a r e s t neighbor i n t e r a c t i o n s which are ordered in a q u a s i p e r i o d i c p a t t e r n a l o n g a o n e - d i m e n s i o n a l c h a i n were s t u d i e d . An e x a c t r e n o r m a l i z a t i o n t e c h n i q u e was u sed which mimics t h e d e f l a t i o n r u l e fo r a q u a s i p e r i o d i c l a t t i c e . The s y s t e m h a s a phase t r a n s i t i o n a t z e r o t e m p e r a t u r e w i t h t h e u s u a l s c a l i n g form of the thermodynamic func t ions . These f u n c t i o n s have c o r r e c t i o n s to s c a l i n g which do not appear in an o r d i n a r y system and which e x h i b i t s p a t i a l dependence in the c o r r e l a t i o n func t ion . REFERENCE:

L"1] Achiam, Y., Lubensky , T. C. and M a r s h a l l , E. W., Phys . Rev. B , i n p r e s s .

CRITICAL BEHAVIOR OF THE KINETIC ISING MODEL ON FRACTALS: I I . THE SIERPINSKI

CARPETS"1" [ 1 ] Y. Achiam

The k i n e t i c I s i n g model on t h e f r a c t a l S i c r p i n s k i c a r p e t s was s t u d i e d [ 1 , 2 ] . D i f f e r e n t c a r p e t s w i t h d i f f e r e n t d i m e n s i o n a l i t i e s were examined u s i n g a r e n o r m a l i z a t i o n - g r o u p t r ans fo rma t ion . The c a l c u l a t i o n s were performed w i t h i n the Migdal approximat ion. The s c a l i n g b e h a v i o r of t h e m a g n e t i c f i e l d , and t h e dynamic e x p o n e n t were o b t a i n e d a t t h e n o n t r i v i a l f ixed p o i n t s of each c a r p e t . REFERENCES: [1] Achiam, Y., Phys . Rev. B (1986) , in p r e s s . [2] Achiam, Y., Phys . L e t t . A J J 2 , 161 (1985) .

CRITICAL DYNAMICS OF THE KINETIC ISING MODEL ON THE FRACTAL KOCH CURVES * [1 ] Y. Achiam

The c r i t i c a l s l o w i n g down of t h e k i n e t i c G l a u b e r - I s i n g model on d i f f e r e n t f r a c t a l g e o m e t r i e s w i t h q u a s i l i n e a r l a t t i c e s was s t u d i e d . The c l a s s e s of f r a c t a l s which were examined a r e the nonbranching Koch c u r v e s a n d t h e b r a n c h i n g Koch c u r v e s . The r e l a x a t i o n of two d i f f e r e n t p e r t u r b a t i o n s from e q u i l i b r i u m was examined. The dynamic c r i t i c a l exponent was c a l c u l a t e d f o r t h e s e l a t t i c e s u s i n g an e x a c t r e n o r m a l i z a t i o n - g r o u p t r a n s f o r m a t i o n . The va lue z = 1/v+Dj. was found for both f r a c t a l s . REFERENCE: [1] Achiam, Y., Phys . Rev. B 32, 1796 (1985) .

+ This work was performed a t the U n i v e r s i t y of P e n n s y l v a n i a , P h i l a d e l p h i a , PA, U.S.A. U n i v e r s i t y of Pennsy lvan ia , P h i l a d e l p h i a , PA, U.S.A.

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CRITICAL DYNAMICS OF THE KINETIC ISING MODEL ON FRACTAL GEOMETRIES* [1]

Y. Achiam

The c r i t i c a l dynamics of t h e k i n e t i c G l a u b e r - I s i n g model on d i f f e r e n t f r a c t a l geometr ies was s tud i ed . The c l a s s e s of f r a c t a l s which were examined a r e the nonbranching Koch c u r v e s , the branching Koch c u r v e s , and the two-dimensional S i e r p i n s k i gaske t . The c r i t i c a l dynamic exponent was c a l c u l a t e d fo r t h e s e m o d e l s u s i n g an e x a c t r e n o r m a l i z a t i o n - g r o u p t r a n s f o r m a t i o n . The v a l u e z = 2.58 f o r t h e t w o - d i m e n s i o n a l S i e r p i n s k i g a s k e t a g r e e s w i t h r e c e n t r e s u l t s from e x p e r i m e n t s pe r fo rmed i n a p e r c o l a t i n g system. REFERENCE: [1] Achiam, Y., Phys. Rev. B 31_, 4732 (1985) .

THE DIFFRACTION SPECTRUM OF A GENERAL FAMILY OF LINEAR QUASIPERIODIC ARRAYS I . Aviram

We s t u d i e d t h e d i f f r a c t i o n s p e c t r u m and t h e s t r u c t u r e f a c t o r of q u a s i - c r y s t a l l i n e , a p e r i o d i c , l i n e a r a r r a y s w i t h two a r b i t r a r y c h a r a c t e r i s t i c incommensurate measure l e n g t h s , produced by a f a i r l y g e n e r a l family of g e n e r a t i n g r u l e s depending on two parameters . The c a l c u l a t i o n i s performed by a c t u a l l y c o n s t r u c t i n g the two-dimensional p e r i o d i c s t r u c t u r e whose p r o j e c t i o n w i l l r e s u l t i n t h e d e s i r e d l i n e a r a p e r i o d i c a r r a y . D i s t r i b u t i o n s of some sequences of i r r a t i o n a l numbers modulo 1 were de r ived as a by-product . REFERENCES: [1 ] de B r u i j n , N. G. , Proc . Ned. Akad. Wet. A84, 27, 1981. [2 ] E l s e r , V. , Phys. Rev. B 3_2, 4892, 1985. [3 ] Levine , D, and S t e i n h a r d t , P . J . , Phys . Rev. L e t t . 53 , 2177, 1981.

CRITICAL RELAXATION OF THE ONE-DIMENSIONAL BLUME-EMERY'-GRIFFITHS MODEL*+ [ 1 ] Y. Achiam

A model for the c r i t i c a l r e l a x a t i o n in the one-d imens iona l I s i n g -t y p e S = 1 s p i n sys tem was d e v e l o p e d . T h i s model i s e q u i v a l e n t t o t h e Blume-Emery-Gri f f i ths model and e x h i b i t s two s imple c r i t i c a l p o i n t s and one t r i c r i t l c a l p o i n t . The k i n e t i c behav io r was s t ud i ed us ing the r e a l - s p a c e r e n o r m a l i z a t i o n - g r o u p approach. In the two c r i t i c a l p o i n t s we found t h a t t h e c r i t i c a l s l o w i n g down i s d e s c r i b e d by t h e dynamic e x p o n e n t z, z = 2. In each p o i n t t h i s exponent b e l o n g s t o the c r i t i c a l o rde r parameter , wh i l e t h e second o r d e r p a r a m e t e r r e l a x e s f a s t e r , w i t h z = 1 o r 0 . At t h e c r i t i c a l p o i n t the two order pa ramete rs r e l a x with the same z, z = 1. REFERENCE: [ 1 ] Achiam, Y., Phys. Rev. B 3J_, 260 (1985) .

This work was performed a t the U n i v e r s i t y of Pennsy lvan i a , P h i l a d e l p h i a , PA, U.S.A. The work was s u p p o r t e d by t h e N a t i o n a l S c i e n c e F o u n d a t i o n , u n d e r g r a n t No. DMR-82-16178.

7

REPLY TO "COMMENT ON 'CRITICAL RELAXATION OF THE ONE-DIMENSIONAL BLUME'-EMERY-CRIFFITHS MODEL*"+ [1 ]

Y. Achiam The v a l u e of t h e dynamic e x p o n e n t , z, which c h a r a c t e r i z e s t h e

c r i t i c a l r e l a x a t i o n of t he one-d imens iona l Bluwe-Emery-Gr i f f i ths model was found by Weir and K o s t e r l i t z to be i n c o r r e c t . The c o r r e c t v a l u e , z = 2, i s found us ing a r e n o r m a l i z a t i o n - g r o u p t r a n s f o r m a t i o n i n a d i f f e r e n t parameter space . In t h i s parameter space, which i s coupled t o t he t h r e e components o f t h e S = 1, t h e m a s t e r e q u a t i o n i s i n v a r i a n t u n d e r an e x a c t r e n o r m a l i z a t i o n - g r o u p t r a n s f o r m a t i o n . REFERENCE: [1 ] Achiam, Y., Phys . Rev. B 3 1 , 623 (1986) .

A GAMMA RAY LASER BASED ON INDUCED ANNIHILATION OF ELECTRON-POSITRON PAIRS

A. Loeb and S. E l i e z e r The c o h e r e n t a m p l i f i c a t i o n of gamma r a d i a t i o n of a s y s t e m of

pa rapos i t ron ium atoms was proposed and the n o n l i n e a r o p t i c s of pos i t r on ium media was ana lyzed . The induced a n n i h i l a t i o n t r a n s i t i o n s for t h e e l e c t r o n -p o s i t r o n plasma were compared wi th t h o s e of the pos i t ron ium medium. I t was sugges ted t h a t the B o s e - E i n s t e i n condensa t ion could p l a y a c r u c i a l r o l e in t he e s t i m a t i o n of the induced a n n i h i l a t i o n of e l e c t r o n - p o s i t r o n p a i r s for d e n s e (n > 1 0 2 0 cm~3) and c o l d (T < 10 K) p o s i t r o n i u m s y s t e m s . . The c a l c u l a t e d e f f e c t s of t h e i n d u c e d p o s i t r o n - e l e c t r o n d e c a y s m i g h t be obse rved in a s t r o p h y s i c a l o b j e c t s , such as p u l s a r s , white dwarf s t a r s , e t c . Fur thermore , t he se t r a n s i t i o n s might p l a y an important r o l e in K l e i n - A l f v e n cosmology. F i n a l l y , wi th the f u r t h e r advancement of p o s i t r o n t echno logy , a gamma ray l a s e r may be cons t ruc t ed .

QUANTUM MECHANICAL STUDY OF THE D + H- • > HD + H REACTION [1 ] N. AbuSalbi , D. J . Kouri , Y. Shima and M. Baer

A quantum m e c h a n i c a l s t u d y was made of t h e D + H^Cv^ = 0 ,1 ) > HD(vf = 0,1,2) + H r e a c t i o n s wi th in t he i n f i n i t e o rder sudden approximat ion (IOSA) f o r t h e t o t a l e n e r g y i n t e r v a l 0.28 ^ Et 4 1.28 eV. R e s u l t s a t v a r i o u s s t a g e s of t h e c a l c u l a t i o n r a n g e from most d e t a i l e d r e a c t i v e t r a n s i t i o n p r o b a b i l i t i e s t h r o u g h o p a c i t y func t ions and y-dependent c r o s s s e c t i o n s t o t o t a l and s t a t e - t o - s t a t e i n t e g r a l and d i f f e r e n t i a l c r o s s s e c t i o n s , a s w e l l a s r a t e c o n s t a n t s . The c r o s s s e c t i o n s and r a t e c o n s t a n t s were compared with o t h e r a v a i l a b l e t h e o r e t i c a l r e s u l t s and exper iments . I t was found t h a t t h e IOSA t o t a l c r o s s s e c t i o n s f o r v^ = 0,1 o v e r l a p v e r y n i c e l y w i t h t h e c o r r e s p o n d i n g q u a s i c l a s s i c a l t r a j e c t o r y c r o s s s e c t i o n s , except for the t u n n e l i n g reg ion . A l e s s s a t i s f a c t o r y f i t was o b t a i n e d wi th

This work was performed a t the U n i v e r s i t y of P e n n s y l v a n i a , P h i l a d e l p h i a , PA, U.S.A. University of Houston, Houston, TX, U.S.A.

8

t h e d i s t o r t e d wave Born a p p r o x i m a t i o n r e s u l t s . The c a l c u l a t e d r a t e c o n s t a n t s were compared with experiment and a r a t h e r good f i t was o b t a i n e d , in p a r t i c u l a r for r a t e c o n s t a n t s from t h e ground s t a t e . REFERENCE:

[1] A b u S a l b i , N., K o u r i , D. J . , Shima, Y. and B a e r , M.f J . Chem. P h y s . 82_, 2650 (1985) .

A STUDY OF THE PARALLEL MOLECULE-SURFACE REACTION HCl + SURFACE > H...SURFACE + C I : A COMPARISON BETWEEN QUANTUM MECHANICAL AND QUASI-CLASSICAL TRAJECTORY RESULTS [ 1 ]

Y. Shima and M. Baer The quantum e f f e c t s a s encountered in r e a c t i o n s of g a s - s o l i d - s u r f a c e

i n t e r a c t i o n s were s t u d i e d . The r e a - j t i j n chosen wi.s H C l ( v i = 0,1 , . . . , 4 ) + s u r f a c e > H . ^ s u - f a c p + CI

where t h e HCl m o l e c u l e was assumed t o a p p r o a c h t h e s u r f a c e w h i l e t i i n g p a r a l l e l t o i t ( i . e . , y = I T / 2 ) . R e s u l t s due t o quantum m e c h a n i c a l and q u a s i - c l a s s i c a l t r a j e c t o r y t r e a t m e n t s were compared and sometimes l a r g e d i f f e r e n c e s were encountered i n d i c a t i n g the importance of quantum e f f e c t s . The model assumed for t h i s t r e a t m e n t i n h e r e n t l y i n c l u d e s c o r r u g a t i o n and p a r t of t h e s t u d y was d e v o t e d t o t h e i n f l u e n c e of c o r r u g a t i o n on t h e r e s u l t s . REFERENCE: [1 ] Shima, Y. and Baer , M., J . Chem. Phys. 83 , 5250 (1985) .

A STUDY OF LIGHT-HEAVY MASS TYPE MOLECULES REACTING WITH A SOLID SURFACE [ 1 ]

S. Ron, Y. Shima and M. Baer

Some f e a t u r e s of a d i a t o m i c m o l e c u l e i n t e r a c t i n g w i t h a s o l i d s u r f a c e were s t u d i e d employing the c l a s s i c a l t r a j e c t o r y method [ 1 , 2 ] . The f o c u s was m a i n l y on t h e l i g h t - h e a v y (LH) mass c o m b i n a t i o n t y p e m o l e c u l e wi th emphasis on r e a c t i v e (exchange) and d i s s o c i a t i v e p r o c e s s e s .

We would l i k e t o draw a t t e n t i o n t o one p a r t i c u l a r c a s e f o r t h e LH s y s t e m , t h e HI d i a t o m i c m o l e c u l e , where t h e r o t a t i o n of H b r i n g s t h e Y a n g l e v e r y c l o s e t o TT[Y= COS ' ( R T ) ] . We found t h a t t h e r e a c t i o n e x c h a n g e p r o c e s s was i n h i b i t e d and t h e i n t e r a c t i o n ended up b e i n g n o n r e a c t i v e . The r e a s o n f o r t h i s i s a s f o l l o w s . Wheny a p p r o a c h e s y^, which i s ~ IT, t h e s l o w l y r o t a t i n g H atom a c t u a l l y " r i d e s " on t h e i o d i n e . The iod ine , wh i l e moving away from the s u r f a c e pushes ou t t he H atom and in t h i s way i n h i b i t s t h e hydrogen from being adsorbed on t h e s u r f a c e , and t h u s t he i n e l a s t i c c o l l i s i o n s do not d i s appea r even for h igh e n e r g i e s (F igs . 1 and 2 ) .

In o rde r t o e x p l a i n why the d i s s o c i a t i v e channe l cannot be reached , even for e n e r g i e s as high as 100 eV, we sugges t t he use of a f r ee s p e c t a t o r model.

9

Fig. 1

Transition probabilities as a function of total energy for

the HI + S system.

• adsorption probability; o reaction probability;

+ inelastic transition probability

Fig. 2

The angle vB as a function of translational energy for HI

as calculated for different initial Y0 values

REFERENCES:

[1] Ron, S., Shima, Y. and Baer, M., Chem. Phys. Lstt. n_6, 3 (1985).

[2] Ron, S., Shima, Y. and Baer, M., Chem. Phys. Jl_01_, H5 (1986).

10

GASEOUS FISSION PRODUCT RETENTION BY SOLID SURFACES [1]

S. Ron, M. Baer and Z. B. Alfassi*

In the present study theoretical models were developed to evaluate

kinetic data corresponding to gaseous fission product retention by solid

surfaces. A specific study was performed for the iodine/iron system. The

results are in good agreement with the experimental values.

The quasiclassical trajectory method was employed. First we

calculated a noncorrugated rigid surface model, and subsequently a dynamic

(energy absorbing) and corrugated surface model was developed, representing

more realistic behavior.

The reaction rate constant for gaseous molecules reacting with a

corrugated and dynamic surface is given by

K 1 ( T ) = 4u

+R 2TT -IT/2 r t i t t ! °° °°

-R 0 -IT/ 2 -o

I f \ I I f1(T,v,j).f2(T,Vz).f3(;) • V=0 J=0

V V-/V x y z

' VT'V'f5(T'V'f6(Qs,V-Vz \

• F,(V . v , j , ? , V ,V ,Q ,P )r2drd<t>sinYdYdV dV dV

where k i (T) i s t h e r a t e c o n s t a n t fo r t h e i t y p e r e a c t i o n a t t e m p e r a t u r e T(K).V2,V ,VX a r e t h e t h r e e componen t s of t h e i n i t i a l v e l o c i t y , v and j a r e the i n i t i a l v i b r a t i o n a l and r o t a t i o n a l quantum numbers, r e s p e c t i v e l y , r i s t h e i n i t i a l i n t e r m o l e c u l a r d i s t a n c e and o r i e n t a t i o n . Q s and P s a r e the su r f ace o s c i l l a t i o n c o o r d i n a t e and momentum, r e s p e c t i v e l y . The v a r i o u s f a r e the p r o b a b i l i t y d e n s i t y func t ions (PDF) of the mo lecu le s accord ing t o the pa rame t r i c combinat ions (where only Fl has a s imple d e s c r i p t i o n hav ing a value of 0 or 1 ) .

The Monte C a r l o method was employed , where f 1 , TH and f5 were sampled us ing the Re jec t ion method. Due to the s p e c i a l importance of the f2 func t ion , an improved Re jec t ion method was used by sampl ing in d i s c r e t e i n t e r v a l s . f3 / f6 were sampled us ing the CDF method. REFERENCE: [1] Ron, S., B a e r , M. and A l f a s s i , Z. B. , i n : T r a n s . N u c l . Soc . I s r a e l ,

v o l . 1 3 , 1986 , p. 103-


1 1

SPONTANEOUS ALIGNMENT IN CHARGED-PARTICLE SYSTEMS: FIXED-LENGTH vs. MICELLAR

SITUATIONS"*"

W. E. McMullan*, Y. Rosenfeld and W. M. Ge lba r t* In t h i s work we used a r e c e n t l y deve loped v e r s i o n [ 1 ] of the s o i t -

m e a n - s p h e r i c a l approximat ion [2 ] (SNSA) t o t r e a t spontaneous a l ignment i n s u s p e n s i o n s of i o n i c , r o d l i k e p a r t i c l e s . I n p a r t i c u l a r , our t h e o r y d e r i v e s [33 from the charge-smear ing idea of Onsager in which a lower bound i s e s t a b l i s h e d f o r t h e f r e e e n e r g y of t h e i n t e r a c t i n g s y s t e n u F i r s t we t r e a t e d t h e u s u a l c a s e of f i x e d - p a r t i c l e l e n g t h s and e s t a b l i s h e d t h e regimes in which t h e charged l i n e s behave l i k e hard s p h e r o c y l i n d e r s ( i . e . t he "smearing" l e n g t h p l a y s t he r o l e of a ha rd -co re d i ame te r ) . In g e n e r a l , t he nematic phase i s superceded by the s o l i d whenever t h e rod l e n g t h i s too s m a l l or too l a r g e . Then we cons ide red , e x p l i c i t l y , the m i c e l l a r s i t u a t i o n i n which t h e p a r t i c l e l e n g t h s a r e d e t e r m i n e d by t h e t h e r m o d y n a m i c s (and v i c e v e r s a ) . Here we found the p o s s i b i l i t y of a r e e n t r a n t i s o t r o p i c phase : a t low t e m p e r a t u r e s t h e n e m a t i c becomes u n s t a b l e b e c a u s e t h e a l i g n m e n t -i n d u c e d g rowth l e a d s t o t o o l a r g e a c h a r g i n g ( " s e l f " ) e n e r g y f o r t h e m i c e l l e s . We a l s o p r e d i c t e d an i d e a l - s o l u t i o n - l i k e behav io r for t he growth of m i c e l l e s in s u f f i c i e n t l y c o n c e n t r a t e d i s o t r o p i c phases . F i n a l l y , t he d i f f e r e n c e s be tween our c h a r g e - s m e a r i n g d e s c r i p t i o n of s p o n t a n e o u s a l i g n m e n t in i o n i c s y s t e m s and a c o l l e c t i v e - c o o r d i n a t e a p p r o a c h due t o Deutsch and Goldenfe ld [4 ] were cons ide red . REFERENCES:

[ 1 ] Rosenfe ld , Y. and Ge lbe r t , W. M., J . Chem. Phys . 8±, 4574 (1984) . [2 ] Rosenfe ld , Y. and Ashcrof t , N. W., Phys. Rev. A 20, 2162 (1979) . [31 Rosenfeld , Y., Phys . Rev. A 25 , 1206 (1982) . [4] D e u t s c h , J . M. and G o l d e n f e l d , N. D., J . Phys . ( P a r i s ) _4_3, 651 ( 1 9 8 2 ) .

l

INTERNAL HEAT DISTRIBUTION OF AN IRRADIATED SPHERE

E. Bar-Ziv, B. S. Gorin , A. F. Sarofim , J. P. Longwell and R. E. Spjut

The phenomenon of explosion of liquid droplets and solid aerosols

within combustion systems was investigated. Several mechanisms were

proposed to explain this phenomenon. In most of the mechanisms, internal

boiling (or decomposition) within the aerosol was involved. A mechanism

that has not been suggested thus far is a build-up of temperature within

the particle that would cause internal boiling or decomposition. This

would lead to internal pressures sufficient to explode the particle.

Equilibrium systems involving conductive (or convective) heat transfer can

not create such conditions. However, radiation transfer effects may cause

internal absorption which may generate internal temperature peaks.

+Work supported in part by ACS grant No. PRF 14050-AC7 and NSF grant

No. CHE 83-20196.

University of California, Los Angeles, CA, U.S.A.

Massachusetts Institute of Technology, Cambridge, MA, U.S.A.

1 2

In a p r e v i o u s s t u d y we c a l c u l a t e d a b s o r p t i o n c e n t e r s w i t h i n an i r r a d i a t e d sphere u s ing the f u l l Mie c a l c u l a t i o n s . The i n t e r n a l a b s o r p t i o n d i s t r i b u t i o n shows s t r o n g d e p e n d e n c e on t h e o p t i c a l p r o p e r t i e s of t h e a e r o s o l . In t h e p r e s e n t s t u d y we u s e d t h i s i n t e r n a l a b s o r p t i o n f i e l d a s t h e s o u r c e t e r m f o r h e a t t r a n s f e r , s o l v e d t h e c o n d u c t i o n e q u a t i o n s and c a l c u l a t e d t h e tempera tu re f i e l d w i t h i n the p a r t i c l e .

EXCITATION OF A CIRCULAR LOOP THROUGH A SMALL APERTURE [ 1 ]

H. Yatom and R. Ruppin The p r o b l e m of d e t e r m i n i n g t h e c u r r e n t e x c i t e d on a c i r c u l a r l o o p

which i s p l a c e d o p p o s i t e a s m a l l c i r c u l a r a p e r t u r e in a conduct ing sc reen , on which an e l e c t r o m a g n e t i c p l a n e wave i s i n c i d e n t , was cons idered . I t was shown t h a t t h i s geome t ry i s u n u s u a l i n t h a t t h e r e s u l t i n g i n t e g r o -d i f f e r e n t i a l e q u a t i o n can be r e d u c e d t o an e x p l i c i t e x p r e s s i o n f o r t h e c u r r e n t . The t o t a l r a t e of e l e c t r o m a g n e t i c energy flow in t he r a d i a t i o n zone was a l s o c a l c u l a t e d , as was t h e a n g u l a r dependence of the energy f l u x . Sample r e s u l t s d e m o n s t r a t e t h e r e s o n a n t b e h a v i o r of t h e s y s t e m when t h e wavelength of the i n c i d e n t wave i s equal t o t he loop c i rcumference . REFERENCE: [ 1 ] Yatom, H. and Ruppin, R., IEEE Trans . Antennas Propag. 3_3, 101 (1985) .

ELECTROMAGNETIC FIELD INTERACTION WITH FAST-MOVING DIPOLES

M. S t r a u s s , G. Kur izk i , J . Oreg and A. Ben-Reuven The two c o n v e n t i o n a l H a m i l t o n i a n s of quantum e l e c t r o d y n a m i c s ,

n a m e l y , t h e m i n i m a l - c o u p l i n g (p.A) and t h e m u l t i p o l a r (u.E) Hami l ton i ans a r e known t o y i e l d the same r a t e s of resonance t r a n s i t i o n s ( a b s o r p t i o n or e m i s s i o n ) f o r s t a t i o n a r y a toms . These two H a m i l t o n i a n s , r e l a t e d by t h e P o w e r - Z i e n a u c a n o n i c a l t r a n s f o r m a t i o n , were shown t o p r o d u c e i d e n t i c a l r a t e s for moving d i p o l e s , in t he n o n r e l a t i v i s t i c l i m i t ( v / c « 1 ) o n l y i f the m a g n e t i c moment a s s o c i a t e d w i t h t h e moving d i p o l e i s i n c l u d e d i n t h e m u l t i p o l a r i n t e r a c t i o n . The e f f e c t of the motion i s then, r e g a r d l e s s of the chosen Hami l ton ian , a r e d u c t i o n of the d i p o l e - f i e l d c o u p l i n g c o n s t a n t by a f ac to r of 1 - v q /c , where q i s t h e u n i t v e c t o r in the d i r e c t i o n of the e m i t t e d or a b s o r b e d r a d i a t i o n . In t h e c a s e of d i p o l e s a s s o c i a t e d w i t h r e l a t i v i s t i c sp in - 1 / 2 p a r t i c l e s (e.g. , e l e c t r o n s or p o s i t r o n s channe led in c r y s t a l s [ 1 ] ) , the c o u p l i n g c o n s t a n t ob ta ined from the Dirac Hami l ton ian d i f f e r s from t h a t of t h e n o n r e l a t i v i s t i c l i m i t by a f a c t o r of 2 Y / ( T + 1) . where Y = 0~V /C )~ . The wave equation and generalized N-particle Bloch equations were written in terms of e lectr ic-f ie ld and polarization operators of the active modes, with the motionally-reduced fleld-dipole coupling constants, thus providing the framework for the analysis of spontaneous emission, superfluorescence and lasing from ensembles of fast-

Weizmann Institute of Science, Rehovot Tel-Aviv University, Ramat-Aviv

13

moving dipoles. The f i r s t -o rde r per turba t ive r e s u l t for the Y~dependence of gain obtainable by single-mode f i e l d s t imulat ion of channeling rad ia t ion from r e l a t i v i s t i c e l e c t r o n s [2 ] was r e t r i e v e d from t h i s a n a l y s i s in the small-Tp, s teady-s ta te , sma l l - s igna l regime. Subs tant ia l modifications of t h i s Y-dependence were predicted in other regimes. REFERENCES: [1] Kurizki, G. and Mclver, J . K., Phys. Rev. B 32, 1358 (1985). [2] B e l o s h i t s k i i , V. V. and Kumakhov, M. A., Sov. Phys. JETP JT7, 652

(1978).

AVERAGE ENERGY SHIFT DUE TO CONFIGURATION INTERACTION J . Oreg, M. Klapisch and A. Bar-Shalom

Closed formulas for the average energy s h i f t of a g e n e r a l j - j c o n f i g u r a t i o n due t o i n t e r a c t i o n s with any o the r c o n f i g u r a t i o n were developed. The dependence of the various contr ibut ions to the sh i f t on the occupation numbers of the various s h e l l s was determined. The importance of the average energy sh i f t s to the in te rp re ta t ion of unresolved spectra [1 ] was considered. REFERENCES: [1] Bauche-Arnoul t , C , Banche, J . and Klap i sch , M., Phys. Rev. A £C), 2121,

(1979).

REACTING TURBULENT FLOW PRODUCED BY TWO CONCENTRIC TUBES OF FINITE WALL THICKNESS I . Geyer, A. Apelblat and E. Bar-Ziv

A numerical model was developed to ca l cu l a t e heat and mass t ransfer in reac t ing turbulent flow produced by two concentric tubes separated by a wa l l of f i n i t e thickness. Spalding et a l . have studied a somewhat s imi lar problem but with a zero wal l thickness. The r e s u l t a n t parabol ic equations of the p r e s e n t problem can not be s o l v e d by the S p a l d i n g codes; we therefore developed a new numerical procedure. Equations of motion, energy and mass, as wel l as turbulence (described by the k-model), were expressed in a two-dimensional parabolic form in cy l i nd r i ca l coordinates (assuming s t e a d y - s t a t e , a x i a l symmetry, and a predominant d i r e c t i o n of f low). The equa t ions were conver ted i n t o f i n i t e - d i f f e r e n c e equa t ions to be s o l v e d n u m e r i c a l l y by the marching i n t e g r a t i o n method. I t was not p o s s i b l e to so lve the equations d i r e c t l y , e i the r in the x - r coordinate system or in the x-w system used by S p a l d i n g e t a l . ( r and x a re the r a d i a l and a x i a l coordinates r e spec t ive ly , and w i s the normalized stream function). The former led to numerical i n s t a b i l i t i e s , the l a t t e r is not app l icab le at the f i r s t s teps of the ca l cu l a t i ons . Therefore, the x~r coordinate system was used for the f i r s t two ax ia l s teps and then the equations were transformed i n t o the x-w system for the f u r t h e r course of the c a l c u l a t i o n s . The

Ben-Gurion University of the Negev, Beer-Sheva

^^

numerical code developed c a l c u l a t e s p r o f i l e s of v e l o c i t i e s , composi t ions and t e m p e r a t u r e s in t h e f l a m e . As an e x a m p l e , a h y d r o g e n / a i r f l a m e was chosen . I t was assumed t h a t immedia te l o c a l e q u i l i b r i u m i s a c h i e v e d . Chemical composit ion was c a l c u l a t e d from thermodynamic data . The e f f e c t of w a l l t h i c k n e s s , f l o w v e l o c i t i e s , and i n i t i a l c h e m i c a l c o m p o s i t i o n was s t u d i e d .

MODELLING THE EXTERNAL WORLD OF AN AUTONOMOUS ROBOT M. Goldste in

The problem addressed by t h i s work i s t he e x t e r n a l world modeling of an au tonomous r o h o t u s i n g r a n g e d a t a . Range d a t a q u a n t i f y t h e d i s t a n c e s from the s e n s o r f o c a l p l a n e t o t h e o b j e c t s u r f a c e , a l o n g r a y s e m a n a t i n g from p o i n t s on a r e g u l a r 3-D s p a c e g r i d . Unique r e q u i r e m e n t s f o r such a w o r l d model a r e : a) m i n i m a l memory fo r s t o r i n g and b) e f f i c i e n t use f o r n a v i g a t i o n purposes.

The e x t e r n a l w o r l d m o d e l i n g p r o p o s e d h e r e i s b a s e d on t h e C o m b i n a t i o n a l Geometry (CG) [ 1 ] which i s w i d e l y used i n M o n t e - C a r l o s i m u l a t i o n s for e f f i c i e n t c a l c u l a t i o n of d i s t a n c e s t o 3~D s u r f a c e s . In CG, s o l i d s a r e r e p r e s e n t e d a s c o m b i n a t i o n s of p r i m i t i v e s o l i d s ( s p h e r e s , c y l i n d e r s , e t c . ) u s i n g t h e B o o l i a n o p e r a t i o n s of u n i o n , i n t e r a c t i o n s , complement, e t c . The proposed a l g o r i t h m proceeds as f o l l o w s . F i r s t , each p o i n t of the space g r i d i s surrounded by a s m a l l s o l i d sphere w i th a r a d i u s determined by the range. Then, the 3-D shapes of the v i s i b l e su r f ace a r e obta ined d i r e c t l y , by t a k i n g the union of a l l t he spheres . The d i s t a n c e s from the r o b o t l o c a t i o n t o t h e v a r i o u s o b j e c t s a r e c a l c u l a t e d u s i n g t h e e f f e c t i v e CG procedure . This approach was used for t e s t i n g a n a v i g a t i o n a lgo r i t hm for a s p h e r i c a l robot in a 3~D room, wi th s t a t i c o b s t a c l e s . REFERENCE: [1] L i c h t e n s t e i n , H., Cohen, M.O., S t e i n b e r g , H.A., T r o u b e t z k o y , E. S. and

Baer , M., The SAM-CE Monte C a r l o System fo r R a d i a t i o n T r a n s p o r t and C r i t i c a l i t y C a l c u l a t i o n s in Complex C o n f i g u r a t i o n s ( R e v i s i o n 7 .0 ) , Computer Code M a n u a l , C.C.M-8, M a t h e m a t i c a l A p p l i c a t i o n s Group, Elmsford, New York, 1979.

15

SOME SAFETY ASPECTS OF MODULAR HTGR J . Szabo and E. Greenspan

One of the unique f e a t u r e s of modular HTGR [ 1 , 2 ] i s t h e i r i n h e r e n t , or p a s s i v e , s a f e t y , which p r e c l u d e s a s i g n i f i c a n t r e l e a s e of r a d i o a c t i v i t y , g i v e n any combination of t e c r . i i c a l ma l func t ions and human e r r o r s . This i s due to a combination of the f o l l o w i n g f e a t u r e s : low c o o l a n t p r e s s u r e , low c o o l a n t energy con ten t , h igh h e a t c a p a c i t y and the rma l c o n d u c t i v i t y of the c o r e and r e f l e c t o r , and u s e of h e a t r e s i s t e n t c e r a m i c m a t e r i a l s and g r a p h i t e f o r t h e f u e l c l a d d i n g . The i n h e r e n t s a f e t y f e a t u r e of m o d u l a r HTGR was b o r n e ou t by a number of s a f e t y s t u d i e s which c o n s i d e r e d " i n t e r n a l l y " i n i t i a t e d a c c i d e n t s ( i . e . due to t h e mal func t ion or f a i l u r e of componen t s , o r t o o p e r a t o r e r r o r s ) a s w e l l a s t o c e r t a i n " e x t e r n a l l y " i n i t i a t e d a c c i d e n t s , such as l o s s of o f f s i t e power and ear thquakes .

I n t h e p r e s e n t work we examined t h e i m p l i c a t i o n s r e g a r d i n g t h e s a f e t y of m o d u l a r HTGR of y e t a n o t h e r t y p e of " e x t e r n a l l y " i n i t i a t e d a c c i d e n t s namely, a c c i d e n t s r e s u l t i n g from a c t s of war. Ways of r educ ing t h e damage by a c t s of war and t h e i r economic c o n s e q u e n c e s were a l s o s t u d i e d . The m o d u l a r HTGR p l a n t d e s i g n p r o p o s e d by B e c h t e l [ 2 ] was cons ide red in t h i s i n v e s t i g a t i o n .

P r e l i m i n a r y a s s e s s m e n t i n d i c a t e s t h a t by a d o p t i n g s i m p l e , i nexpens ive meaures i t i s p o s s i b l e t o des ign modular HTGR such t h a t they do n o t impose a r a d i o l o g i c a l h a z a r d t o t h e p o p u l a t i o n even i n c a s e of war. Furthermore, i t i s p o s s i b l e t o make the p r o b a b i l i t y of damage t o s e n s i t i v e components of the r e a c t o r n e g l i g i b l e , i f not t o e l i m i n a t e them a l t o g e t h e r , and t h u s t o s i g n i f i c a n t l y r e d u c e t h e i n v e s t m e n t r i s k due t o a c t s of war. These f e a t u r e s make r e a c t o r concep ts such as modular HTGR of much appea l for a country l i k e I s r a e l . I f f u l l b e n e f i t i s to be drawn from the unique sa fe ty f e a t u r e s of HTGR, p r o t e c t i v e measures a g a i n s t a c t s o f war should be inco rpora t ed in the des ign from i t s i ncep t i on . REFERENCES: [1] IAEA, S t a t u s of and P r o s p e c t s for Gas-Cooled Reactors , IAEA Techn ica l

Reports S e r i e s No. 235 , Vienna, 1984. [2] GCRA, E v a l u a t i o n of Smal l Modular High Temperature Gas-Cooled Reac tors

Applied to E l e c t r i c i t y Genera t ion , Gas Cooled Reactor A s s o c i a t e s Report GCRA 84-002 (1984) .

LOSS OF OFFSITE POWER ANALYSIS WITH DSNP

D. Saphier

ATWS (Anticipated Transients Without Scram) were analyzed with the DSNP [1] simulation language, to determine i t s a b i l i t y to simulate typica l PWR a c c i d e n t and t r a n s i e n t sequences . In the present t ransient ana lys is the i n i t i a t i n g event i s a t o t a l l o s s of o f f s i t e power in a t y p i c a l Westinghouse four loop 3411 MWt PWR. The da ta used for the a n a l y s i s are based on the Trojan FSAR.

19

The l o s s of power caused l o s s of the main feedwater pumps and the four primary c o o l a n t pumps. No r e a c t o r t r i p or ECCS were assumed t o be act ivated during the f i r s t 500 sec into the t r a n s i e n t .

The DSNP simulat ion i s a very coarse lumped parameter representat ion of the power p lant . The t rans ien t is i n i t i a t e d a t - 1 sec by t r ipp ing a l l the pumps. The r e s u l t s were compared with the audit c a l c u l a t i o n s performed by B a t t e l l e [2] wi th the RELAP-3B code. The sequence of some e v e n t s a s ca lcu la t ed by DSNP and RELAP-3B are given in Table 1.

Table 1 Sequence of events for the loss of o f f s i t e power

All pumps t r i p PORV open Pressurizer solid (fills)

Steam space regained - first time

Steam space regained >- second time

RELAP

Is 6s

31s 137s

360s

DSNP

1s 6S

32s 13^3 385s

Some representative results are shown in Fig. i, which shows the

pressure in the pressurizer, and Fig. 2 which presents the combined flow of

the relief and safety valves. The results obtained with DSNP compare well

with the RELAP results, but are not identical. Further development and

refinement of the DSNP simulation is underway.

200 300 Time (sec)

Fig. 1 P re s su re t r a n s i e n t in the p r e s s u r i z e r dur ing the f i r s t

500 sec of a loss of o f f s i t e power accident

20

22

o j ^ 18 U o> -!£ 6>I4

3 o - 10 Q) f/> O <U Q) p.

2

Fig . 2 Combined r e l i e f and s a f e t y v a l v e f l o w d u r i n g

a l o s s of o f f s i t e power a c c i d e n t

REFERENCES:

[1] S a p h i e r , D., The S i m u l a t i o n Language of DSNP: Dynamic S i m u l a t o r f o r Nuclear - Power - P l a n t s , e d i t e d by T.N. Buchanan, ANL-CT-77-20, Rev. 3.4 ( 1 9 8 3 ) .

[2 ] B a t t e l l e Memorial I n s t i t u t e , S e l e c t e d ATWS Audit C a l c u l a t i o n s for the PWR Designs (Dec, 1982), p r i v a t e communication.

THE SENSITIVITY OF THE PRESSURIZER RESPONSE TO PORV SETTING UNDER SIMULATED ACCIDENT CONDITIONS D. Saphier

R e c e n t l y a new p r e s s u r i z e r model was d e v e l o p e d fo r t h e DSNP [ 1 ] s i m u l a t i o n language. The mathemat ica l model and the assumpt ions made in i t s development a r e given in Ref. 2.

I n t h i s s t u d y t h e s e n s i t i v i t y of t h e p r e s s u r i z e r r e s p o n s e t o t h e v a l u e s of v a r i o u s design parameters was t e s t e d . Only a l i m i t e d number of e x p e r i m e n t a l l y measured t r a n s i e n t s a r e a v a i l a b l e for model v a l i d a t i o n . T h i s i s t r u e i n p a r t i c u l a r f o r t h e e x t r e m e o p e r a t i n g c o n d i t i o n s when t h e p r e s s u r i z e r i s f l o o d e d o r empty. The s e n s i t i v i t y of t h e r e s p o n s e t o a p a r t i c u l a r parameter p r o v i d e s a measure of the v a l i d i t y of the c a l c u l a t e d r e sponse .

The p r e s s u r i z e r was c o n n e c t e d t o a s i m p l i f i e d s i m u l a t i o n of t h e primary loop and the s e n s i t i v i t y of the p r e s s u r i z e r r esponse to the PORV (Power Operated R e l i e f Va lve ) c h a r a c t e r i s t i c s was i n v e s t i g a t e d . The PORV r e s p o n s e i s f a s t ; i t i s assumed t o be f u l l y open when t h e p r e s s u r e i n t h e p r e s s u r i z e r r i s e s above 16.2 MPa and i t i s assumed to be f u l l y c l o s e d when the p r e s s u r e i s below 16.2 MPa. These c h a r a c t e r i s t i c s cause the v a l v e t o

200 300 Time (sec)

400 500

21

oscillate rapidly as shown in Fig. 3 while maintaining a constant pressure

of 16.2 MPa in the pressurizer until it becomes solid.

50

§ 40

~ 30 s

Z 20 a

£ 10

0 0 4 8 12 16 20 24 28

Time (sec)

Fig. 3 Comparison of flows through PORV, assuming different modes of operation

The operating characteristics of the PORV were changed to provide

some hysteresis in its operation. The number of oscillations was reduced

significantly as the hysteresis was increased. This had a significant

effect on reducing simulation computer time with increasing hysteresis:

AP = 102 Pa Cpu = 5918 sec for 600 sec real time

AP = 101* Pa Cpu = 1979 sec for 600 sec real time

AP = 105 Pa Cpu = 1936 sec for 600 sec real time

Following the above tests the valve was assumed to behave as a linear

function of the pressure in the range of 16.2 MPa to 16.21 MPa. This

caused the valve response to be stable, the pressure changed slowly between

16.2 and 16.21, and the flow became a time average of the previous cases.

The execution time was, however, reduced by a factor of 10 and more (CPU

time for 600 sec simulation was 185 sec). Both responses are compared in

Fig. 3. The other system variables were not sensitive to the relief valve

mode of operation.

It can be concluded that the pressurizer response is not sensitive

to the mode of operation of the PORV, however the CPU time necessary to

follow the valve oscillations can be very large.

REFERENCES:

[1] Saphier, D., The Simulation Language of DSNP, ANL-CT-77-20, Argonne

National Laboratory, Rev. 3.1 (1983).

[2] Saphier, D. and Kalfelz, J., in: Trans. Nucl. Soc. Israel, vol. 12,

1985, p. 118.

22

Continuous operation

On-off operation with hysteresis of I 0 4 Pa

TESTING THE UTSG DSNP MODULE SIMULATION OF A LOFW TRANSIENT

D. Gal, D. Saphier and E. Elias+

In order to test and verify the DSNP UTSG module [1] dynamic

performance, a LOFW transient in a typical Westinghouse plant was

investigated. The input data for the simulation were based on the SEQUOYAH

reference manual [2]. The dynamic boundary conditions of the UTSG during

LOFW transient were taken from a RELAP3B [3] simulation. These boundary

conditions included the primary side inlet temperature, pressure and flow.

For the secondary side, feedwater enthalpy and turbine trip boundary

conditions were used.

The transient was simulated for 120 sec, starting with the feedwater

pump trip at t=0 sec.

The resulting scenario is shown in Table 2. The times of turbine

trip, safety valve activation, and startup of the auxilliary FW pump are

presented.

Table 2

Event sequence for a LOFW transient

Time (sec)

Event DSNP LOFTRAN RELAP3B

Main feedwater ramped to

zero over 4 sec (input)

Turbine is assumed to

trip (input)

UTSG safety valves open

Auxiliary feedwater

initiation (input)

UTSG tubes are uncovered

(exit quality) = 0.9)

0-4

30

45

60

60.2

0-4

30

43

60

67.0

0-4

30

46

60

61.3

The modeling of the dryout was based on the assumption of a linear

function relating the heat transfer drop to the two-phase mixture quality.

Good agreement between the DSNP simulation RELAP3B, and LOFTRAN [4] results

was obtained, as shown in Fig. 4, which presents the secondary SG pressure

as calculated by the DSNP and RELAP3B codes.

#*

***

Technion, Israel Institute of Technology, Haifa

*UTSG - U-Tube Steam Generator

DSNP - Dynamic Simulator of Nuclear Power Plants

LOFW - Loss of Feedwater

23

85

*TJ Q .

-* O X



0.

80

75

70

65

60

55

50

45

40 0 I 2 3 4 5 6 7 6 9 10 II 12

Time * 10 (sec)

Fig. H

SG steam dome pressure during LOFW transient

REFERENCES:

[1] Gal, D., Saphier, D. and Elias, E. in: IA-HI12, 1985, p. 23.

[2] Technology Manual - Pressurized Water Reactor, Westinghouse Design,

U.S.-NRC, 1983-

C3] RELAP3B Manual, A Reactor System Transient Code, BNL, RP/035, 197U.

[4] Burnett, T. W. T. et. al., "LOFTRAN Code Description", WCAP - 7907,

1972.

AN IMPROVED PRESSUR1ZER MODEL FOR DSNP*

D. Saphier

Many pressur izer models, ranging from very simple to ra ther complex can be found in the l i t e r a t u r e [1 ,2 ] . These models suffer from one or more of the following l i m i t a t i o n s : equil ibrium conditions assumed, bubble r i s e -e v a p o r a t i o n and condensa t ion not modeled or o v e r s i m p l i f i e d , extreme condit ions such as flooding of water phase removal not modeled, wa l l heat c a p a c i t y n e g l e c t e d . In the p r e s e n t model a r i g o r o u s t r ea tmen t of the energy and mass balance equations was performed and no a p r io r i simplifying assumptions were made.

Dynamic Simulator for Nuclear Power Plants

2H

In the new DSNP [3 ] module PRESR2, four nodes were assumed, nonequilibrium conditions were permitted, f lashing and condensation models were included and de ta i led modeling of the various safety and r e l i e f va lves was included.

The new model can operate under extreme operating conditions such as f looded or p r e s s u r i z e r s o l i d c o n d i t i o n s and p r e s s u r i z e r empty. This permi ts the p r e s s u r i z e r t o be used in the s i m u l a t i o n of a wide range of operating conditons.

A schematic descript ion of the l e v e l - 2 pressurizer model PRESR2 i s p resen ted in Fig. 5. The p r e s s u r i z e r i s a c y l i n d r i c a l v e s s e l of about 50 nP ( s tandard Westinghouse 3400 MWt PWR des ign) con ta in ing about 30 m saturated water at a PWR operating pressure of 15.4 MPa, and a steam dome of 20 nP c o n t a i n i n g s a t u r a t e d steam. These two volumes r e p r e s e n t e d as nodes a re shown in the f i gu re . Both the steam dome and the water volume have a w a l l node a s s o c i a t e d with them. As the p r e s s u r i z e r l e v e l changes (moving boundary), the mass associated with the wall of each of the above nodes changes appropriately.

Spray

wslsv

*

w K

Wall

Twg

Qwg

Twf

Qwf

w porv

hh

Vg P Tg vg hg

Pq Vgshgs

^we wc

Vf Tf vf h f t

Pf vfs h fs I

Q h

w;

Primary Loop

Fig. 5

Schematic description of the level^2 pressurizer model

25

The model was t e s t e d i ndependen t ly and as a p a r t of a PWR s i m u l a t i o n f o r a wide r a n g e of t r a n s i e n t s . The s i m u l a t i o n r e s u l t s a r e i n a g r e e m e n t wi th o the r p r e d i c t i o n s . REFERENCES:

[1 ] Baron, R. C., Nuc l . S c i . Eng. 52 283 (1983) . [2] Alhani , V. V. and Vijaykumar, L . , Nucl . Technol . 6± 517 (1983) . [33 S a p h i e r , D., The S i m u l a t i o n Language of DSNP, ANL-CT-77"20, Argonne

Na t iona l Labora to ry , Rev. 3 .1 (1983) .

A GENERAL-PURPOSE LUMPED'-PARAMETER STEAM-GENERATOR MODEL D. Saphie r and D. Gal

A s imple f i v e - n o d e lumped parameter (LP) steam gene ra to r (SG) model to be used wi th t h e DSNP s i m u l a t i o n s of n u l c e a r power p l a n t s was deve loped . U s u a l l y LP models have a very l i m i t e d range of a p p l i c a b i l i t y mos t ly in t h e v i c i n i t y of s t e a d y s t a t e c o n d i t i o n s , and can t h e r e f o r e be u sed o n l y i n minor o p e r a t i o n a l t r a n s i e n t s .

The p r e s e n t model has f i v e LP nodes , namely, t he primary c o o l a n t , t h e SG t u b e s and o t h e r m e t a l p a r t s , t h e b o i l i n g w a t e r , t h e s u p e r h e a t e d r e g i o n , and t h e s t e a m dome. A " B o i l i n g K e t t l e " a p p r o a c h was used i n t h e model ing, p r o p e r l y a v e r a g i n g the hea t t r a n s f e r c o r r e l a t i o n over subcooled and n u c l e a t e b o i l i n g , assuming pool b o i l i n g a t low or ze ro f low, and us ing the D i t t u s B o e l t e r c o r r e l a t i o n in t he primary and supe rhea ted nodes. The model pe rmi t s water l e v e l t r a c k i n g and t h e p r e s s u r e in the steam dome i s a l s o c a l c u l a t e d w i t h t h e s e c a p a b i l i t i e s . The s i m u l a t i o n of e x t r e m e c o n d i t i o n s such a s SG d r y o u t or SG f l o o d i n g can be p e r f o r m e d . The model can be used t o s i m u l a t e e i t h e r a U - t u b e (UTSG) o r a o n c e - t h r o u g h SG model and due to the f l e x i b i l i t y of m a t e r i a l p rope r ty h a n d l i n g in DSNP, can have any primary f l u i d such a s water , he l ium or sodium.

Figure 6 shows the water l e v e l in a t y p i c a l Westinghouse UTSG dur ing l o s s of f e e d w a t e r a c c i d e n t . The f e e d w a t e r f l o w was ramped down t o z e r o

18

14

1 10 _1

6

2 0 10 20 30 40 50 60

Time (sec)

Fig. 6

Steam generator water level during a loss of feedwater flow accident

26

b e t w e e n 1 t o 1 s e c . As can be s e e n , t h e w a t e r l e v e l d e c r e a s e s a t a r e l a t i v e l y m o d e r a t e r a t e d u r i n g t h e f i r s t 120 s e c u n t i l t h e U - t u b e s a r e u n c o v e r e d . T h e r e a f t e r t h e r e i s a s h a r p d e c r e a s e due t o t h e r e d u c e d mass per u n i t l e n g t h between the U- tubes , and f i n a l l y the r a t e of d e c r e a s e s lows down aga in a s t h e major p a r t of the U-tube i s uncovered. The SG d r i e s ou t a t about 250 sec . Th i s dryout t ime i s t y p i c a l for t he above cond i tons and was v e r i f i e d w i t h a RELAP s i m u l a t i o n . I t was c o n c l u d e d t h a t , a l t h o u g h a c o a r s e lumped parameter approach i s used, t he model can be used t o s i m u l a t e extreme t r a n s i e n t cond i tons .

IMPROVED WATER STEAM PROPERTY FUNCTIONS FOR DSNP

D. Saphie r and Z. Guo The o r i g i n a l w a t e r - s t e a m p r o p e r t y f u n c t i o n s i n DSNP use t h e

H e l m h o l t z f r e e e n e r g y f u n c t i o n [ 1 ] ^ = 4, (v ,T) t o c a l c u l a t e w a t e r - s t e a m p r o p e r t i e s fo r a r a n g e o f s t a t e v a r i a b l e s , g i v e n any c o m b i n a t i o n o f two s t a t e v a r i a b l e s . Al though the p r o c e s s r e s u l t e d in a c c u r a t e p r o p e r t y v a l u e s (Keenan and Keys [ 1 ] t a b l e s were reproduced w i t h i n 0.01 %) t h e c a l c u l a t i o n s a r e very t ime consuming.

A new DSNP [ 2 ] module, WASHP1, was deve loped which upon f i r s t e n t r y w i l l gene ra t e a m u l t i d i m e n s i o n a l t a b l e , u s ing the above f u n c t i o n s acco rd ing t o t h e u s e r s p e c i f i e d r a n g e d a t a . On e a c h s u b s e q u e n t e n t r y , o n l y a t a b l e lookup i s neces sa ry .

9*I02

8*I02

x 9 2 g 7*I02

§ 6*I02

o

o 5M02

w x . 4*I02

=>_

* 3xl02

o

P 2x|02

IMOr

0 0 30 60 90 120 150 180 210 240 270 300

P(bar) Fig. 7

Saturated vapor properties as a function of pressure

Georgia Institute of Technology, Atlanta, GA, U.S.A.

21

P-T p-VG P-UG P-HG P-SG P-CP P-DRDP P-DRDH

ph\-~... j

The difficulty in setting up the tables is due to the existence of divergence points near the sa tura t ion l i ne and near the c r i t i c a l point (Pc - 22.15 MPa, T = 374.2C). This i s demonstrated in Fig. 7 which shows saturated vapor proper t ies as a function of pressure. (Note that the variables are normalized.) The rapid changes in the properties near the c r i t i ca l l ine are obvious from the figure. In order to preserve reasonable accuracy near the saturation line and the c r i t i ca l point a complex grid of unequal intervals was used. The resulting table and interpolation schemes

gave accuracy better than 1$ for a l l the state variables, except the ~ -dp

a n d Ih p a r t i a l d e r i v a t i v e s in the v i c i n i t y of the c r i t i c a l point. From severa l simulation s tudies performed using the new water-steam

p r o p e r t y func t ion i t can be concluded t h a t CPU time s a v i n g s of up t o one order of magnitude can be achieved. REFERENCES: [1] Keenen, J . H., Keyes, F. G., M i l l , P. G., and Moore, J . G., Steam

Tables, Wiley, NY 1969. [2] Saph ie r , D., The S imu la t i on Language of DSNP, ANL-CT-77-20, Rev 3.4,

1983.

EXAMINATION OF FILLED NUCLEAR FUEL

V. Henzel and Y. Ronen

In this work we analyzed the possibility of filling annular fuels

with ceramic oxides for use as a thermal fuse in the case of accidental

meltdown. We chose a number of ceramic materials having melting points

close to that of uranium oxide. The analysis considers nuclear and thermal

properties of the filler material and its compatibility with the fuel, the

influence of the filler on the neutron multiplication factor (K^, and the

delay in the meltdown of the fuel due to the melting of the filler.

The ceramic materials proposed as fillers for the annular fuel were

selected to meet the following requirements:

a. minimum Influence on the neutron population (low absorption cross

section),

b. minimum activation of the filler,

c. good chemical resistance of the filler,

d. thermal linear expansion close to that of U02,

e. good metallurgical stability at high temperatures,

f. melting point close to that of UOg,

g. high latent heat of the filler,

h. high density of the filler,

i. good heat transfer coefficient of the filler.

The thermal analysis of the filled fuel was performed on beryllia

(BeO) and on depleted uranium oxide (DU). We examined two different volume


28

r a t i o s of void/ fuel and f i l l e r / f u e l , made.

The following four assumptions were

a. At LOCA heat removal i s based on convection and conduction to the steam and on heat rad ia t ion .

b. The heat capacity of the cladding i s neglected. c. Cladding melting i s neglected. d. The power density in the fuel is constant.

The the rmal a n a l y s i s was based on numer ica l s o l u t i o n of the time dependent hea t t r a n s f e r equa t ions [ 1 ] , c a l c u l a t i n g the t ime between shutdown to the melting point of the f i l l e r mater ia l and the melting point of the fuel . Calcula t ions were performed for severa l f i l l e r s and for two different volume r a t i o s between f i l l e r and fuel .

The behavior of the tempera ture of the f u e l a f t e r shutdown wi th a LOCA i s given in Fig. 8. As shown, the ceramic oxide (be ry l l i a ) f i l l e d in the ho l low space of an a n n u l a r fue l could de lay the meltdown for some minutes. This time may be c r i t i c a l during a LOCA.

3000

2000

I000

Fue[ melting point

Inner radius

0 70 140 J_

280 420 t(sec)

3073 K

2843 K

560

F i g . 8 T e m p e r a t u r e s in t h e f u e l rod a f t e r shu tdown a s

a f u n c t i o n of r a d i u s and t i m e

REFERENCE:

[1] Wak i l E l , N u c l e a r Heat T r a n s p o r t , Chap. H, R e a c t o r Heat G e n e r a t i o n INTEXT, Scran ton , 1971, pp. 94-100.

BENCHMARKING CODES FOR RESEARCH REACTOR CALCULATIONS A. Misulovin and A. Schneider

Our computer codes for the n e u t r o n i c s a n a l y s i s of thermal r e a c t o r s were compared with t hose used in seven o t h e r n u c l e a r c e n t e r s by running the benchmark p r o b l e m [ 1 ] of t h e IAEA. T h i s i s a 10 MW, swimming-poo l t y p e

29

MTR, 6x5 e lement co re , r e f l e c t e d by a g r a p h i t e row on two oppos i t e s i d e s , and s u r r o u n d e d by w a t e r . The e n r i c h m e n t s c o n s i d e r e d were 93 wt$ and 20 vt%.

I t was found t h a t o u r r e a c t i v i t y , f l u x d i s t r i b u t i o n s and Pu p roduc t i on c a l c u l a t i o n s a r e i n very good agreement w i th t h e ave rage r e s u l t s o b t a i n e d in the o t h e r seven o r g a n i z a t i o n s . REFERENCE: [1 ] R e s e a r c h R e a c t o r Core C o n v e r s i o n from t h e Use of H i g h l y E n r i c h e d

Uranium t o t h e Use of Low E n r i c h e d Uranium F u e l s , IAEA-TECDOC-233, I n t e r n a t i o n a l Atomic Energy Agency, 1980.

THE LEAKAGE TRANSFER MATRIX (LTM) METHOD FOR THE SOLUTION OF RADIATION DEEP-PENETRATION PROBLEMS [ 1 ] Z. Shayer and E. Greenspan

The Leakage T r a n s f e r Matr ix (LTM) method i s aimed a t t he c a l c u l a t i o n of t h e a n g u l a r f l u x of n e u t r o n s and /o r photons l e a v i n g a system sub j ec t ed t o an e x t e r n a l n e u t r o n sou rce , as w e l l as of the d o s e - r a t e and t h e r e sponse of any d e t e c t o r l o c a t e d beyond the system. E s s e n t i a l l y , i t i n v o l v e s t he d i v i s i o n of t h e s y s t e m i n t o s m a l l s u b r e g i o n s ; c a l c u l a t i n g , u s i n g c o n v e n t i o n a l S n methods, t he p r o b a b i l i t y t h a t each a n g u l a r f l u x component e n t e r i n g a s u b r e g i o n f o r t h e f i r s t t i m e from t h e s o u r c e s i d e w i l l c o n t r i b u t e to any of the a n g u l a r components of the f l u x of n e u t r o n s / p h o t o n s e m e r g i n g from t h e o t h e r ( i . e . d e t e c t o r ) s i d e of t h e s u b - r e g i o n ; and p r o p e r l y f o l d i n g the a n g u l a r components of the source wi th the r e s u l t i n g LTM, subreg ion a f t e r subreg ion .

By a p p l y i n g t h e LTM method to s imple monoenerget ic one-d imens iona l homogeneous problems, i t was found t h a t t he LTM method r e c o n s t r u c t e d the l e a k a g e f l u x from a 120 mfp t h i c k system t o w i th in 3% of the l eakage f l u x c a l c u l a t e d c o n v e n t i o n a l l y us ing ANISN, w h i l e the CPU t ime r e q u i r e d for t he LTM method was o n l y - 1 / 5 t o 1/15 t h a t r e q u i r e d f o r ANISM, d e p e n d i n g on whether t h e Sj, or S.,g approximat ion was used in both c a s e s .

I t was concluded t h a t t he LTM method can be u s e f u l for c e r t a i n deep-p e n e t r a t i o n problems and shou ld be f u r t h e r examined. REFERENCE: [1 ] S h a y e r , Z. and G r e e n s p a n , E., i n : T r a n s . N u c l . Soc . I s r a e l , v o l 1 3 ,

1986, p . 26.

ON VIOLATION OF THE PRINCIPLE OF LINEAR-SUPERPOSITION BY DISCRETE-ORDINATE CODES [ 1 ]

Z. Shayer and E. Greenspan The s o l u t i o n s of a l i n e a r i z e d B o l t z m a n n e q u a t i o n , such as t h e

n e u t r o n a n d / o r p h o t o n t r a n s p o r t e q u a t i o n , a r e t o obey t h e p r i n c i p l e of l i n e a r s u p e r p o s i t i o n , t h a t i s , the ampl i tude of t h e f l u x a t a g i v e n phase -space i n t e r v a l r due to a g iven combinat ion of sou rces shou ld equal the sum

30

of f luxes a t _r, each of which corresponds to a different source component (the sum of which makes up the f u l l source of the reference problem).

While a p p l y i n g the d i s c r e t e - o r d i n a t e s codes ANISN and DOT-3.5 for the so lu t ion of neutron t ranspor t problems using the recen t ly developed LTM method [2] we encountered s i t u a t i o n s in which the p r i n c i p l e of l i n e a r -s u p e r p o s i t i o n was not p r e s e r v e d . C o n s i d e r f o r i l l u s t r a t i o n , a monoenerget ic problem c o n s i s t i n g of a one-d imens iona l s l a b a l s o of a uniform composition, 12 cm in thickness, represented by twelve 1 cm thick i n t e r v a l s . The absorption, s ca t t e r ing and t o t a l macroscopic cross sect ions a r e s e l e c t e d t o be , r e s p e c t i v e l y , 0 .1 , 0.9 and 1.0 cm"1. The system i s subjected to a boundary source, the amplitude of the angular components of which i s unity. A vacuum boundary condition is applied to both boundaries.

Table 3 Contributions of the forward angular source components (S^ and S^) to the forward angular f lux components (fy and $5), and the r e l a t i v e devia t ion of the l inear-superposi t ion of the S^ and S,- components, ca lcu la ted with the

ANISN "mixed-mode", from the exact r e s u l t s

S p a t i a l i n t e r v a l

1 2 3 4 5 6 7 8 9

10 11 12.

"Exact".

<J>, Components

b 4

0.13345 0 .75527-1 0 .44086-1 0 .25734-1 0 .15028-1 0 .87715-2 0 .51168-2 0 .29795-2 0 .17257-2 0 .98376-3 0 .53345-3 0 .22597-3

S5

0.29996 0.17673 0.10320 0.60253-1 0.35177-1 0.20533-1 0.11978-1 0.69745-2 0.40397-2 0.23028-2 0.12487-2 0.52896-3

r e s u l t s -

4>_ Components

S 4

0.19243 0.11338 0 .66203-1 0 .38654-1 0 .22568-1 0 .13175-1 0.76887-2 0 .44827-2 0 .26061-2 0 .15022-2 0 .84385-3 0 .42616-3

S 5

0.45574 0.26542 0.15497 0.90482-0.52828-0.30840-0.17998-0.10493-0.61003-0.35165-0.19753-0.99758-

-1 • 1

•1 •1 •1 •2 -2 • 2

-1

R e l a t i v e

u

67.57 12.19 11.69 11.68 11.68 11 .68 11 .68 11 .68 11 .68 11 .68 11 .68 11 .68

d e v i a t i o n (%)d

*5

- 4 .28 11.54 11.68 11.68 11.68

•11.68 11.68 11.68 11.68 11.68 11.68 11.68

a) Calculated using the "linear-mode" (IFLU-1) in terpola t ion scheme. b) Angular flux component cf>n corresponds to d i rec t ion cosine y = 0.5300212,

whereas $c corresponds to p= 0.8688906. c) Sw i s the y= 0.5300212 source component, whereas S,- co r responds to

y = 0.8688906. d) [Linear-superposit ion of the S^ and S,- components ca lcu la t ed using the

"mixed-mode" ( i .e . , IFLU = 1) in te rpo la t ion scheme] [exact r e s u l t s ] - 1 (expressed in percent) .

31

The p r o b l e m i s s o l v e d w i t h ANISN u s i n g t h e S^ a p p r o x i m a t i o n i n two w a y s : a) t h e s t r a i g h t f o r w a r d or " i n t e g r a l " a p p r o a c h , i n which t h e s y s t e m i s s u b j e c t e d t o t h e a c t u a l s o u r c e , and b) t h e " s u p e r p o s i t i o n " a p p r o a c h , i n which the c o n t r i b u t i o n of each source a n g u l a r component t o t he a n g u l a r f l u x t h r o u g h o u t t h e s y s t e m i s f i r s t c a l c u l a t e d , and t h e o v e r a l l f l u x d i s t r i b u t i o n is then ob ta ined by super impos ing the c o n t r i b u t i o n s from a l l s o u r c e componen t s . Volume s o u r c e s of i n f i n i t e s i m a l l y s m a l l t h i c k n e s s e s were used for r e p r e s e n t i n g su r f ace s o u r c e s in ANISN.

T a b l e 3 s u m m a r i z e s t h e r e s u l t s t h u s o b t a i n e d u s i n g two d i f f e r e n t numer ica l i n t e r p o l a t i o n o p t i o n s b u i l t in ANISN: a) the "mixed-mode" op t ion (which i s t h e o p t i o n recommended f o r g e n e r a l u s e ) and b) t h e " l i n e a r " o p t i o n . I t was found t h a t t h e p r i n c i p l e of l i n e a r s u p e r p o s i t i o n i s conserved when the l i n e a r i n t e r p o l a t i o n scheme i s used. This p r i n c i p l e i s v i o l a t e d , however, when us ing the "mixed-mode" i n t e r p o l a t i o n scheme.

I t was conc luded t h a t t he ANISN and DOT-3.5 codes may not p r e s e r v e t h e p r i n c i p l e of l i n e a r - s u p e r p o s i t i o n , so t h a t t h e y s h o u l d be u s e d f o r a p p l i c a t i o n s l i k e the s o l u t i o n of the t r a n s p o r t equa t ion by the LTM method wi th e x t r a ca re . REFERENCES: [1] S h a y e r , Z. and G r e e n s p a n , E., i n : T r a n s . Nuc l . Soc . I s r a e l , v o l . 1 3 ,

1986 , p. 2 1 . [23 i b i d , p . 26.

ADJOINT v s . FORWARD SOLUTION OF ANISOTROPIC TRANSPORT PROBLEMS Z. Shayer and K. Greenspan

I t i s w e l l known t h a t t he c a l c u l a t i o n of the r e sponse of a d e t e c t o r ( r e a l or f i c t i t i o u s ) in a s o u r c e - d r i v e n system can be performed e i t h e r in t h e f o r w a r d or in t h e a d j o i n t s p a c e , and t h a t t h e c o m p u t a t i o n a l e f f o r t r e q u i r e d f o r s o l v i n g a s i n g l e f o r w a r d , o r t h e c o r r e s p o n d i n g a d j o i n t , equa t ion i s comparable. An excep t ion was r e c e n t l y r e p o r t e d by Cacuci e t a l . [ 1 ] ; t h e y e n c o u n t e r e d a p r o b l e m in which a h i g h a n g u l a r q u a d r a t u r e (Sn) o r d e r had t o be used i n t h e f o r w a r d - s p a c e c a l c u l a t i o n s i n o r d e r t o match t h e a c c u r a c y a t t a i n e d i n a low Sn o r d e r a d j o i n t c a l c u l a t i o n . The purpose of the p r e s e n t work was t o f ind an e x p l a n a t i o n for t h i s phenomenon and t o f ind out whether t he i n v e r s e s i t u a t i o n can e x i s t .

I t was found [ 2 ] t h a t t h e a d j o i n t - s p a c e s o l u t i o n of t h e s p h e r i c a l p r o b l e m c o n s i d e r e d by Cacuc i e t a l . [ 1 ] and c h a r a c t e r i z e d by a c e n t r a l s o u r c e was more a c c u r a t e t h a n t h e f o r w a r d - s p a c e s o l u t i o n , due t o t h e s i g n i f i c a n t l y h i g h e r l e v e l o f a n i s o t r o p y o f t h e f o r w a r d s o l u t i o n . The i n v e r s e s i t u a t i o n was found t o p r e v a i l i n a s i m i l a r s p h e r i c a l problem in which the d e t e c t o r was c e n t r a l l y l o c a t e d . REFERENCES: [ 1 ] C a c u c i , D. G., W a g s c h a l , J . J . and Y a a r i , A., N u c l . S c i . Eng. 8l_, U43

(1982) . [ 2 ] S h a y e r , Z. and G r e e n s p a n , E., i n : T r a n s . N u c l . Soc . I s r a e l , v o l . 1 3 ,

1 9 8 6 , p . 17 .

32

HETEROGENEOUS VERSUS HOMOGENEOUS MINIMUM-WEIGHT SHIELD DESIGN [1 ]

Y. Kami and E. Greenspan Minimum w e i g h t i s t h e d e s i g n g o a l f o r c e r t a i n r a d i a t i o n s h i e l d s ,

such a s s h i e l d s f o r s p a c e r e a c t o r s . Most of t h e minimum-weight s h i e l d o p t i m i z a t i o n s done i n t h e p a s t u s e d b o u n d a r y - d i s p l a c e m e n t p e r t u r b a t i o n -t h e o r y b a s e d methods [ 2 , 3 ] d e s i g n e d t o i d e n t i f y t h e l o c a t i o n o f t h e boundar i e s of a p rede te rmined number of d i s c r e t e zones . The purpose of t he p r e s e n t work was t o i n v e s t i g a t e t h e f e a s i b i l i t y of f u r t h e r r e d u c i n g t h e s h i e l d weight by des ign ing i t t o have a cont inuous (o r homogeneous) r a t h e r t h a n d i s c r e t e (o r h e t e r o g e n e o u s ) c o m p o s i t i o n . The i n v e s t i g a t i o n was p e r f o r m e d w i t h t h e a i d of t h e m a t e r i a l - r e p l a c e m e n t o p t i m i z a t i o n code SWAN [ 1 ] , c o n s i d e r i n g s p h e r i c a l s h i e l d s c o n s i s t i n g p r i m a r i l y of t ungs t en and l i t h i u m - h y d r i d e .

I t was found t h a t , c o n t r a r y t o t h e r e s u l t s o b t a i n e d fo r minimum t h i c k n e s s s h i e l d s f o r f u s i o n r e a c t o r s [ 5 , 6 ] , t h e o p t i m a l minimum-weight s p h e r i c a l W-LiH s h i e l d i s he te rogeneous ; the tungs t en i s concen t r a t ed in f o u r d i s c r e t e zones a t t h e i n n e r p a r t of t h e s h i e l d . The h e t e r o g e n e o u s n a t u r e of t h e o p t i m a l s h i e l d i s a t t r i b u t e d , p r i m a r i l y , t o a r e d u c t i o n i n t he secondary photons p roduc t ion p r o b a b i l i t y . Other f a c t o r s c o n t r i b u t i n g to the s h i e l d h e t e r o g e n e i t y a re the dua l s h i e l d i n g func t ion of tungs ten , t he s p h e r i c a l geometry, and the weight c o n s t r a i n t REFERENCES: [1 ] K a m i , Y. and G r e e n s p a n , E., T r a n s . N u c l . Soc. I s r a e l , V o l . 1 3 . 1986,

p . 3 1 . [ 2 ] Engle , W. W., A User Manual for ASOP-ANISN Opt imiza t ion Program, Union

Carbide Corp. Nuclear Div. Report CTC-INF-911 , 1969. [3 ] C h i l d s , R. L. e t a l . , The D e v e l o p m e n t and A p p l i c a t i o n of a D i s c r e t e

Ord ina te s Adjoint Di f fe rence Method for One-Dimensional S h i e l d Weight Opt imiza t ion , Oak Ridge Nat iona l Laboratory , ORNL-TM-1196, 1973.

[1 ] Greenspan, E. e t a l . , SWAN-A Code for t he Ana lys i s and Opt imiza t ion of F u s i o n R e a c t o r N u c l e o n i c C h a r a c t e r i s t i c s , P r i n c e t o n P l a s m a P h y s i c s Labora tory , MATT-1008, 1973-

[ 5 ] G i l a i , D. e t a l . , i n : P r o c e e d i n g s of t h e 6th I n t e r n a t i o n a l C o n f e r e n c e on Radia t ion S h i e l d i n g , Tokyo, Japan, Vo l . I I , 1983, p. 616.

[6 ] Greenspan, E. e t a l . , Fusion Technol . 6, Par t 2A, 619 (1985).

TURBULENCE AND THE FEASIBILITY OF SELF<-C0OLED LIQUIDS-METAL BALNKETS FOR FUSION REACTORS [ 1 ] H. Branover , G. Linn , S. Sukoriansky and E. Greenspan

I t i s commonly a c c e p t e d t h a t t h e i n t e r a c t i o n be tween t h e m a g n e t i c f i e l d of fusion r e a c t o r s (us ing magnetic confinement) and t h e l i q u i d meta l (LM) of s e l f - c o o l e d b l a n k e t s l e a d s to the suppress ion of t u r b u l e n c e and, t h u s , t o a r e d u c t i o n i n t h e h e a t - t r a n s f e r and m a s s - t r a n s f e r r a t e s . The

Ben^Gurion Un ive r s i t y of t he Negev, Beer-Sheva

33

reduction in the hea t - t ransfer coeff icient can s ign i f i c an t l y complicate the des ign of s e l f - c o o l e d LM b l a n k e t s , e s p e c i a l l y when the magnetic f i e l d d i rec t ion is t ransverse to the LM flow d i rec t ion .

A r ecen t e x t e n s i v e expe r imen ta l study [2] e s t a b l i s h e d t h a t the presence of a strong t ransverse magnetic f i e ld can s ign i f i c an t l y enhance ve loc i t y f luc tua t ions in the direct ion perpendicular to the f i e l d , while s u p p r e s s i n g v e l o c i t y f l u c t u a t i o n s p a r a l l e l to the f i e ld . The r e s u l t i n g n o n ~ i s o t r o p i c t u r b u l e n t f i e l d causes no s u b s t a n t i a l momentum t r a n s f e r ( i . e . , no p r e s su re drop enhancement), but can s t r o n g l y enhance hea t and mass t r a n s f e r . The p r e s e n t work a s s e s s e s the i m p l i c a t i o n s t h e s e expe r imen ta l f i n d i n g s might have on the performance of s e l f - c o o l e d LM blankets .

I t was found t h a t the enhanced two-dimens ional t u r b u l e n c e might s i g n i f i c a n t l y i n c r e a s e the a t t r a c t i v e n e s s of se l f -coo led LM blankets by p e r m i t t i n g (a) the des ign of s i m p l e r and cheaper b l a n k e t s , and (b) the a t t a inmen t of lower pumping power r equ i remen t s and/or h igher energy conversion eff ic iency. REFERENCES: [1] Branover , H., Linn, G., Sukoriansky, S. and Greenspan, E., in: Trans .

Nucl. Soc. I s r a e l , v o l . 13, 1986, p. 36. [2] Sukoriansky, S . , Zilberman, I . and Branover, H., Fluids J[, 11 (1986).

MINIMUM THICKNESS LITHIUM-LEAD BLANKETS A. Kinrot and E. Greenspan

Minimizing the blanket thickness i s , in general , a des i rab le design goal, as i t may permit reducing the s ize of the fusion reactor , increasing i t s power density, as wel l as reducing the l i thium and t r i t ium inventor ies . The purpose of t h i s work was to i d e n t i f y the minimum t h i c k n e s s , and the corresponding op t ima l composi t ion, t h a t a b reed ing b l a n k e t based on l i th ium-lead can be designed to have.

The b l a n k e t s cons idered a r e machine- independent and, in a s ense , ideal ized; the blanket is described in a 1-D slab-geometry model and the concentration of i t s constituents (excluding the structural materials) are assumed to vary semi-continuously across i t . Thus, the optimal idealized blankets ident i f ied set a lower l imi t on the minimum thickness, andean guide the design of rea l i s t i c blankets. The investigation was carried out with the aid of the optimization code SWAN using the Sg-P, t ranspor t approximation and a 1 7n + 6y group cross section set col lapsed from the DLC-37 library. Additional detai ls about the calculation procedure used can be obtained from Ref. 1.

I t was found [2] that l i th ium-lead blankets can be designed to provide a tritium-breeding-ratio of 1.2 within less than 22 cm of effective thickness; this is less than half the thickness required in conventional L i17 Pb83 b l a n k e f c s - A number of p o s s i b i l i t i e s for reducing the blanket thickness even below 22 cm were identified.

34

REFERENCES:

[1 ] Greenspan , E., K i n r o t , A. and L e v i n , P . , F u s i o n T e c h n o l . 8_, 619 (1985) . [2 ] K i n r o t , A. and G r e e n s p a n , E. t T r a n s . Am. N u c l . Soc . 49 , 104 (1985) .

OPTIMAL SHIELD CONCEPTS FOR EXPERIMENTAL FUSION DEVICES [1] E. Greenspan, P . Levin and A. Kinrot

P o s s i b i l i t i e s for improving the performance of 60 cm t h i c k uniform c o m p o s i t i o n Fe-HgO s h i e l d s backed by a B^C l a y e r commonly p r o p o s e d f o r e x p e r i m e n t a l f u s i o n d e v i c e s were i n v e s t i g a t e d . T a b l e 4 d e s c r i b e s t h e

Table 4 Characteristics of 60 cm thick shields optimized to minimize the maximum

power density in the superconducting SC coils. Results are normalized to a

source of one 14 MeV neutrons per second. All shields contain at least

5vol? uniformly distributed H20 for cooling

Shield Type

f Reference

(Fe-H„0) + B.Cf £ 4

Fe-H20-B4C

Fe-TiH.-B.C 2 4

Cu-H.O-B.C 2 4

Cu-TiH -B,C 2 4 h

W90-TiH„-B,C 2 4

W/Cu-TiH2 i

Average vol. fraction (%)

HCa/H20/TiH2/B4C

.80.0/20.0

79.8/20.2

79.8/16.9/-/4.3

71.7/5.0/19.1/4.2

80.5/]5.9/-/3.6

71.6/5.0/19.3/4.1

82.1/5.0/12.9/0

80.6/5.0/14.4/-

Max. heat. (W/cm3)

6.66-176

.4.16-17

1.87-17

1.09-17

1.16-17

7.16-18

2.09-18

1.18-18

Radiation effect

Total heat. (Watts)

5.30-16

5.25-16

2.79-16

1.38-16

1.41-16

7.'78-17

3.59-17

1.93-17

Displacements" (dpa/s)

1.18-24

1.67-24

9.95-25

4.77-25

4.54-25

2.48-25

1.42-25

7.53-26

e Dose

(rad/h)

2.00-8

2.73-8

1.54-8

7.07-9

7.09-9

3.68-9

2.00-9

1.06-9

a) Heavy shield constituent (Fe, Cu, W90 or W/Cu)

b) Maximum power density in the SC coils

c) Total power deposited inb the SC coils

d) Maximum atom displacement rate in the SC coils

e) Maximum biological dose rate (taken to represent damage rate to

electrical insulators) in the SC coils

f) These shields include a 2 cm B^C layer beyond the 58 cm Fe-H20 system

g) Read 6.66x10"17

h) W90 is tungsten at 90$ of its theoretical density

i) W/Cu is a tungsten copper composite material consisting of 70% tungsten

and 30% copper

35

s h i e l d types cons ide red , t he average v o l u m e - f r a c t i o n of t h e s e s h i e l d s which were o p t i m i z e d t o m i n i m i z e t h e h e a t i n g r a t e i n t h e s u p e r c o n d u c t i n g (SC) c o i l s , a s w e l l a s o t h e r r a d i a t i o n e f f e c t s beyond t h e s e s h i e l d s . I t was found t h a t the maximum h e a t i n g r a t e i n t he supe rconduc t ing c o i l s cou ld be reduced by as much a s a f a c t o r of -56 r e l a t i v e to the c o n v e n t i o n a l s h i e l d . T h i s i m p r o v e m e n t i n r a d i a t i o n a t t e n u a t i o n i s a t t a i n e d w i t h a p r o p e r d i s t r i b u t i o n of a t ungs t en -coppe r composite m a t e r i a l and t i t a n i u m - h y d r i d e . A 35 cm t h i c k op t ima l W/Cu-TiH- s h i e l d cou ld be a s e f f e c t i v e as the 60 era t h i c k r e f e r e n c e s h i e l d .

Guided by t h e a t t r a c t i v e p e r f o r m a n c e of t h e W/Cu~TiH2 s h i e l d , t h e e f f e c t i v e n e s s of W/Cu and W/Fe c o m p o s i t e m a t e r i a l s was s t u d i e d [ 2 ] a s a f u n c t i o n of c o m p o s i t i o n . I t was found t h a t a W40/Cu60 ( i . e , HO v o l % W + 60 v o l % Cu) and a WSH/Fe1^ m a t e r i a l have a s h i e l d i n g - a b i l i t y e q u i v a l e n t to W90. These t u n g s t e n - b a s e d c o m p o s i t e m a t e r i a l s a r e e x p e c t e d t o be s i g n i f i c a n t l y cheaper than W90, and o f f e r dozens of m i l l i o n s of d o l l a r s in s a v i n g on the cos t of the next g e n e r a t i o n of expe r imen ta l tokamak fusion d e v i c e s . REFERENCES [ 1 ] G r e e n s p a n , E., L e v i n , P . and K i n r o t , A., F u s i o n T e c h n o l . 8_ (1) P a r t 2A,

1026 (1985) . [2] Greenspan, E. and K a m i , Y., T rans . Am. Nucl . Soc. j>0, 440 (1985) .

BORIDES VERSUS HYDRIDES FOR MINIMIZING FUSION REACTOR SHIELD THICKNESS [1 ] A. Kinrot and E. Greenspan

I t h a s r e c e n t l y been p r o p o s e d [ 2 ] t h a t " h y d r i d e s a r e (more) e f f e c t i v e in m i n i m i z i n g t h e f a s t n e u t r o n f l u e n c e , w h i l e b o r i d e s a r e s u p e r i o r in r educ ing the n u c l e a r hea t i ng" , in c o n t r a d i c t i o n to our e a r l i e r f i n d i n g C 3 - 5 ] t h a t t i t a n i u m h y d r i d e i s t h e most e f f e c t i v e s i n g l e l i g h t m a t e r i a l f o r m i n i m i z i n g b o t h t h e h e a t i n g - r a t e and a tom-d i sp lacement r a t e (or f a s t neu t ron f l u e n c e ) , when p r o p e r l y combined with t u n g s t e n (or o the r heavy c o n s t i t u e n t ) . The p r e s e n t work was aimed a t c l a r i f y i n g t h i s apparen t d i s c r epancy .

E x a m i n i n g , f i r s t , t h e two s i n g l e - m a t e r i a l zone s h i e l d s y s t e m s c o n s i d e r e d i n Ref. 1 ( c o n s i s t i n g of t u n g s t e n a t t h e f r o n t s i d e , and t h e h y d r i d e o r b o r i d e m a t e r i a l a t t h e back s i d e of t h e s h i e l d ) , we found t h a t the b o r i d e s (B^C and B ^ H ^ ) indeed o f f e r a lower h e a t i n g - r a t e than TiH2. However , when r e m o v i n g t h e two s i n g l e - m a t e r i a l zone r e s t r a i n t s and s e a r c h i n g f o r t h e o p t i m a l d i s t r i b u t i o n of t h e same s h i e l d c o n s t i t u e n t s , TiH2 was found s u p e r i o r t o the b o r i d e s for minimizing the h e a t i n g - r a t e (as w e l l a s the o t h e r r a d i a t i o n e f f e c t s ) . In f a c t , a proper combinat ion of TiH2

and B[jC i s even b e t t e r than the use of e i t h e r of t h e s e m a t e r i a l s a l o n e .

I t was c o n c l u d e d t h a t : a) t o g e t t h e u t m o s t b e n e f i t from TiH 2 i n a TiH2~W s h i e l d , t h e T iH 2 h a s t o be i n t e r m i x e d w i t h t h e W; b) T iH 2 i s more e f f e c t i v e than e i t h e r B^C or B10H1i( for r educ ing the b l a n k e t h e a t i n g - r a t e ; c) t h e combined use of TiH 2 and B^C i s more e f f e c t i v e f o r r e d u c i n g t h e h e a t i n g - r a t e t h a n t h e use of e i t h e r one o f t h e s e c o n s t i t u e n t s ; and d) a

36

p e r t u r b a t i o n theory -based o p t i m i z a t i o n method, such as that used for the present study, i s very he lpfu l for identifying optimal sh ie ld designs. REFERENCES: [1] Kinrot, A. and Greenspan, E. , Trans. Am. Nucl. Soc. 50, 441 (1985). [2] El -Guebaly , L. A. and Larsen, E. M., Trans. Am. Nucl . Soc. JT7, 381

(1984). [3] G i l a i , D., Greenspan, E. and Levin, P. in Proceedings of the 6th

In te rna t iona l Conference on Radiation Shielding, Tokyo, Japan, Vol. I I , (1983) p. 646.

[4] G i l a i , D., Greenspan, E. and Levin, P., Trans . Am. Nucl . Soc. ^ 5 , 625 (1983).

[5] Greenspan, E. , Levin, P. and Kinrot, A., Fusion Technol. £ , 1026 (1985)

ON THE PROMISE OF TRITIUM-CATALYZED-DEUTERIUM (TCD) FUSION [1] E. Greenspan, G.H. Miley , J . Gil l igan , J . Jung and A. Kinrot

The t r i t i u m - c a t a l y z e d deuter ium (TCD) fusion f u e l c y c l e i s one v e r s i o n of the p a r t i a l l y - c a t a l y z e d deuter ium (PCD) mode of o p e r a t i o n in which a l l the t r i t ium from the D(D,n))T react ion fuses in the plasma while as much of the ^He from the D(D,p)3He react ion which can be recovered from the plasma i s placed in the blanket , where i t i s transmuted into t r i t ium by neutron absorption [ 2 ] . The r e s u l t i n g t r i t o n s are fed into the plasma to undergo another D-T react ion.

The promise of the TCD mode of ope ra t i on for the p roduc t ion of e l e c t r i c i t y and f i s s i l e fuel was recen t ly assessed [3 ] . The present study r e a s s e s s e s the f i s s i l e f u e l p roduc t ion a b i l i t y of the TCD mode of operation, now considering more r e a l i s t i c blanket models.

I t was found that the TCD mode of operation i s even more a t t r a c t i v e for fusion breeder app l ica t ions than rea l i zed e a r l i e r [ 3 ] ; one TCD fusion breeder could suppor t twice as many f i s s i o n r e a c t o r s as a D-T fusion breeder having the same thermal power. REFERENCES: [1] Greenspan, E., Miley, G. H., G i l l i g a n , J . , Jung, J. and Kinro t , A.,

Fusion Technol. 8, 573 (1985). [2] Greenspan, E. and Miley, G. H., Nucl. Technol./Fusion j4, 590 (1982). [3] Greenspan, E., Miley, G. H., Jung, J . and G i l l i g a n , J . , T r i t i um

Catalyzed Deuterium Tokamaks, ANL-FPP/TM-183, 1984.

University of Illinois, Urbana, IL, U.S.A.

North Carolina State University, Raleigh, NC, U.S.A.

Argonne National Laboratory, Argonne, IL, U.S.A.

37

THE RELATIVE IMPORTANCE OF SURFACE/GASEOUS FISSION PRODUCT CHEMISTRY IN REDUCING THE SOURCE TERM [ 1 ]

S . Ron, M. Baer and Z. B . A l f a s s i * I n t h i s s t u d y we e s t i m a t e d t h e c o n t r i b u t i o n of s u r f a c e / g a s e o u s

f i s s i o n p r o d u c t r e t e n t i o n , f o l l o w i n g a h y p o t h e t i c a l s e v e r e a c c i d e n t i n l i g h t water and gas cooled r e a c t o r s , to the Source Term r e d u c t i o n .

The modular High Temperature Gas-Cooled Reactor des ign i s aimed a t keeping most of the f i s s i o n p roduc t s w i t h i n the co re , even a f t e r a s e v e r e a c c i d e n t . T h i s i s a c c o m p l i s h e d in p a r t due t o t h e v e r y s i g n i f i c a n t a d s o r p t i o n of gaseous m o l e c u l e s by g r a p h i t e . However, a l a r g e f r a c t i o n of t h e v e r y s m a l l amount s of f i s s i o n p r o d u c t s r e l e a s e d t o t h e c o n t a i n m e n t might escape to the environment as l i q u i d a e r o s o l s a r e absen t . In LWR, on the o t h e r hand, a l a r g e f r a c t i o n of the f i s s i o n p roduc t s w i l l be r e l e a s e d from t h e core a f t e r the h y p o t h e t i c a l s e v e r e a c c i d e n t , b u t t h e l a r g e amount of aqueous a e r o s o l s , i n h e r e n t l y p r e s e n t in the containment a tmosphere, w i l l d r a s t i c a l l y reduce t he Source Term t o the environment . REFERENCE:

[1 ] Ron, S. , B a e r , M. and A l f a s s i , Z. B. , i n : T r a n s . N u c l . Soc . I s r a e l , v o l . 1 3 , 1986 , p. 110.


38

THE USE OF UNRESOLVED TRANSITION ARRAYS FOR DIAGNOSIS OF HOT PLASMA A. Z i g l e r , S. J a c k e l , A. Ludmirsky, M. Klapish , E. Meroz and A. Bar Shalom

In hot plasma the 3d s u b s h e l l of heavy, h i g h l y ion ized atoms becomes open . The number of l e v e l s i n t h e c o n f i g u r a t i o n s i s v e r y l a r g e and t h e numerous l i n e s a s s o c i a t e d w i t h a t r a n s i t i o n a r r a y c a n n o t be r e s o l v e d because they a r e b l u r r e d by Doppler broadening. The broad "bands" appear i n t h e e x p e r i m e n t a l s p e c t r a . In the case of 3d -1)f t r a n s i t i o n s such "bands" b e l o n g i n g t o t h e d i f f e r e n t i o n i z a t i o n s t a g e s (between N i - l i k e and K - l i k e ) a r e w e l l s e p a r a t e d . With the use of r a r e e a r t h t a r g e t s i r r a d i a t e d by 10J, 2.5 n sec , N d - l a s e r p u l s e s , the appearance of v a r i o u s i o n i z a t i o n s t a g e s was a n a l y z e d by v a r i a t i o n of l a s e r i n t e n s i t y . The b a n d s a r e i d e n t i f i e d by us ing a s imple s t a t i s t i c a l model [ 1 ] , REFERENCE: C1] Klap i sh , M. e t a l . , Phys. Rev. A 25, 2391 (1982) .

RADIATION TRANSPORT AND PREHEAT CALCULATIONS OF LASER IRRADIATED Al TARGETS A. D. Krumbein, D. Salzmann and H. Szichman

C a l c u l a t i o n s were c a r r i e d out of the p r e h e a t of t he c o l d r eg ion of an aluminum t a r g e t by X-ray r a d i a t i o n emi t t ed from the c o r o n a l r eg ion . The computat ion was done by means of our 1-D hydrodynamics code, PLASMOR [ 1 ] , which t a k e s i n t o c o n s i d e r a t i o n non-LTE s t e a d y s t a t e atomic phys ic s . The r a d i a t i o n from the plasma i s d i v i d e d i n t o MO energy groups : 20 con t inuous g r o u p s ( r e c o m b i n a t i o n + b r e m s s t r a h l u n g ) f rom hv = 300 eV up t o hv = 100 keV, and 20 l i n e r a d i a t i o n s , mainly (but not on ly ) H e - l i k e and H-l i k e l i n e s . The hot co rona l r eg ion i s assumed to be o p t i c a l l y t h i n to a l l r a d i a t i o n s . The p h o t o - a b s o r p t i o n in the c o l d p o r t i o n proceeds through the p h o t o - i o n i z a t i o n e f f e c t , and v a r i a t i o n s wi th d e n s i t y and t empera tu re a r e taken i n t o account by means of a s i m p l i f i e d model. Black-body r a d i a t i v e t r a n s p o r t in t h e c o l d p o r t i o n i s a l s o i n c l u d e d . The e f f e c t s of t h e r a d i a t i o n on t h e shock wave p r o p a g a t i o n , a s w e l l a s i t s i n f l u e n c e on t h e d e n s i t y and t empera tu re d i s t r i b u t i o n s in the shock compressed r e g i o n , were s t u d i e d . REFERENCE:

[1] Krumbein, A., Sz ichman , H., S a l z m a n n , D. and E l i e z e r , S. , IA-1396 (1985) .

TWO-DIMENSIONAL ANALYTICAL CONSIDERATIONS OF LARGE MAGNETIC AND ELECTRIC FIELDS IN LASER PRODUCE PLASMA S. E l i e z e r and A. Loeb

A s i m p l e model in two d i m e n s i o n s was d e v e l o p e d and s o l v e d a n a l y t i c a l l y t a k i n g i n t o account the e l e c t r i c and magnetic f i e l d s in l a s e r produced plasmas . The e l e c t r i c p o t e n t i a l in t h i s model i s d e s c r i b e d by the

Hebrew U n i v e r s i t y , J e ru sa l em

41

non-linear differential equation

I^.JM]2 4- lp

3x2 T » 3 X / (1-ifr) = 0

^ = e<j>/T, w h e r e ed> i s t h e e l e c t r i c p o t e n t i a l e n e r g y a n d T i s t h e t e m p e r a t u r e i n e n e r g y u n i t s . The p h y s i c a l b r a n c h ty < 1 , d e f i n e d by t h e e l e c t r o n d e n s i t y n = n 0 expiji, b o u n d a r y c o n d i t i o n s (n(x = 0) = c o n s t and n(x = +co) = 0 ) , i n t r o d u c e s a t y p i c a l e l e c t r o s t a t i c d o u b l e l a y e r . The s t a t i o n a r y s o l u t i o n of t h i s model i s c o n s i s t e n t , f o r ~3.2 < ty < 1 , w i t h e l e c t r o n t empera tu re in the keV r eg ion and a r a t i o of t h e e l e c t r i c (E) t o magnetic (B) f i e l d s of [ E / 1 0 6 v /cm]/ [B/Mgauss] - 1.

FREE ELECTRON LASER AND LASER ELECTRON ACCELERATIONS BASED ON THE MEGA-GAUSS MAGNETIC FIELDS IN LASER PRODUCED PLASMAS

A. Loeb and S . E l i e z e r In t h i s work i t was s u g g e s t e d t h a t t h e m e g a - g a u s s m a g n e t i c f i e l d s

genera ted in l a s e r produced plasmas be a p p l i e d f o r : (a) t he c o n s t r u c t i o n of a w i g g l e r fo r X-ray F r e e E l e c t r o n L a s e r (FEL) and (b) c h a r g e d p a r t i c l e a c c e l e r a t i o n t o high e n e r g i e s us ing the I n v e r s e FEL and the Autoresonance Laser A c c e l e r a t i o n (ALA) schemes. Coherent a m p l i f i c a t i o n of 10 A r a d i a t i o n w i t h a 150 MeV e l e c t r o n beam seems f e a s i b l e and GeV e l e c t r o n beams may i n d u c e a Y~ray l a s e r . An a c c e l e r a t i o n g r a d i e n t of a b o u t [ 1 0 0 MeV/cm] [z(10 cm)]"1 ' a long a 1 MG a x i a l magnetic f i e l d can be ach i eved in the ALA scheme, us ing a Nd:g lass l a s e r of 10 W/em .

AUTORESONANCE LASER ACCELERATOR A. Loeb and L. F r i e d l a n d

A l a s e r e l e c t r o n a c c e l e r a t i o n scheme based on s e l f - s u s t a i n e d c y c l o t r o n r e s o n a n c e was c o n s i d e r e d . N o n l i n e a r e l e c t r o n d y n a m i c s i n combined axisymmetr ic magnetic and t r a n s v e r s e l a s e r r a d i a t i o n f i e l d s was i n v e s t i g a t e d . A n a l y t i c s o l u t i o n s were g iven for a c i r c u l a r l y p o l a r i z e d l u m i n o u s (w/ck = 1) r a d i a t i o n c a s e , which a l l o w s t i m e u n l i m i t e d p h a s e -l o c k i n g between the e l e c t r o n s and the a c c e l e r a t i n g e l e c t r o m a g n e t i c wave. An a p p r o p r i a t e t a p e r i n g of t h e m a g n e t i c f i e l d in t h e s u p e r l u m i n o u s c a s e ( u / c k > 1) can a l s o l e a d t o s i g n i f i c a n t a c c e l e r a t i o n s , r e s t r i c t e d by t h e maximum a v a i l a b l e s t r e n g t h of t h e g u i d e m a g n e t i c f i e l d . The e n t r a n c e c o n d i t i o n s f o r t h e a c c e l e r a t e d beam, a s w e l l a s i t s l a u n c h i n g i n t o t h e d e s i r a b l e a u t o r e s o n a n c e r e g i m e t h r o u g h a t r a n s i t i o n r e g i o n , were cons ide red . I t was shown t h a t the r a d i a t i o n l o s s e s in a 1 TeV a c c e l e r a t o r a r e n e g l i g i b l e . High c u r r e n t beam a c c e l e r a t i o n seems to be f e a s i b l e . A Nd-g lass l a s e r with i n t e n s i t y of 10 W/cm i s capab le of a c c e l e r a t i n g h igh c u r r e n t e l e c t r o n beams from 0.25 t o 2.5 GeV o v e r 1 m by u s i n g a 100 kG guide magnet ic f i e l d .

Hebrew U n i v e r s i t y , Je rusa lem

42

SELF-CONSISTENT SOLUTION FOR THE NONLINEAR DYNAMICS OF DENSE ELECTRON BEAMS IN THE AUTORESONANCE LASER ACCELERATOR A. Loeb and L. F r i ed l and

L a s e r a c c e l e r a t i o n o f d e n s e e l e c t r o n beams a l o n g an a x i s y m m e t r i c m a g n e t i c f i e l d w i t h i n t h e a u t o r e s o n a n c e l a s e r a c c e l e r a t i o n scheme was s t u d i e d . The e q u a t i o n s o f mot ion and t h e c o n t i n u i t y e q u a t i o n fo r t h e e l e c t r o n s were s o l v e d t o g e t h e r wi th Maxwell equa t i ons for t h e l a s e r f i e l d . E f f i c i e n t t r a n s f o r m a t i o n of e l e c t r o m a g n e t i c energy i n t o e l e c t r o n k i n e t i c energy was cons ide red .

THE EFFECT OF PLASMA OSCILLATIONS ON THE RADIATION PROFILE OF THE IMMERSED IONS IN PLASMA* M. S t r a u s s , A. Hayrapet ian , F . Daghighian and N. Rostoker

The e f f e c t of plasmons on the s p e c t r a l l i n e s h a p e of ions immersed i n p l a s m a was s t u d i e d . Us ing a d e n s i t y m a t r i x f o r m a l i s m we showed t h a t , i n a d d i t i o n to the w e l l known s t a t i c s h i e l d i n g e f f e c t s , t h e r e a r e both s h i f t and broadening due to the dynamical e f f e c t s caused by plasma f l u c t u a t i o n s . G e n e r a l e x p r e s s i o n s f o r dynamic s h i f t and b r o a d e n i n g were o b t a i n e d . A s p e c i f i c model of hydrogenic ions immersed in plasma was cons ide red , where the dens i ty of the s h i e l d i n g c loud i s accord ing to Skupsky [ 1 ] . Using the a b o v e r e s u l t s s h i f t and b r o a d e n i n g were c a l c u l a t e d for d i f f e r e n t plasma t empera tu re s and d e n s i t i e s . REFERENCE: [1 ] Skupsky, S . , Phys. Rev. A £1_, 1316 (1980) .

NON-EQUILIBRIUM EXCITATION PHENOMENA NEAR THE PLASMA-SUBSTRATE SURFACE IN A LOW PRESSURE MICROWAVE PLASMA Y. L. Khait , A. I n s p e k t o r , U. Carmi and R. Avni

The l u m i n o u s p l a s m a l a y e r (PL) r e g i o n formed a round a g rounded o r n e g a t i v e l y biased s o l i d s u b s t r a t e ( g r a p h i t e or Si s i n g l e c r y s t a l ) immersed in a microwave plasma a t low p r e s s u r e s (1 to 1*0 Torr) was i n v e s t i g a t e d by o p t i c a l e m i s s i o n s p e c t r o s c o p y (OES). OES m e a s u r e s e x c i t e d p l a s m a p a r t i c l e s , and those s p u t t e r e d away from the s u b s t r a t e s u r f a c e .

The e x c i t a t i o n and i o n i z a t i o n phenomena i n t h e PL were c o r r e l a t e d with the h igh energy secondary e l e c t r o n s e m i t t e d from the s u b s t r a t e s u r f a c e and a c c e l e r a t e d towards t he plasma by the n e a r - t o - s u r f a c e e l e c t r i c f i e l d . This high energy e l e c t r o n beam (HEEB) c o n s t a n t l y bombards the PL p a r t i c l e s . The s p u t t e r e d e x c i t e d p a r t i c l e s of t h e PL w e r e i d e n t i f i e d and d i f f e r e n t i a t e d from those of the plasma bu lk . The t h i c k n e s s of the PL was

Hebrew U n i v e r s i t y , J e rusa lem + This work was performed a t the U n i v e r s i t y of C a l i f o r n i a , I r v i n e , CA,

U.S.A. University of California, I rvine, CA, U.S.A. Ben-Gurion Unversity of the Negev, Beer-Sheva

M3

e v a l u a t e d by a t h e o r e t i c a l model b a s e d on t h e HEEB i n d u c e d - e x c i t a t i o n p r o c e s s and was found to be i n agreement wi th e x p e r i m e n t a l measurements of t h e PL. P l a s m a s of a r g o n and of m i x t u r e s of a r g o n w i t h n i t r o g e n o r hydrogen were i n v e s t i g a t e d .

RECENT ADVANCES IN CERAMIC COATINGS BY CHEMICAL VAPOR (CVD) AND PLASMA PROCESSING (PPD) DEPOSITION R. Avni and U. Carmi

The r e a c t i v e g a s e s o r v a p o r s fed i n t o e i t h e r a CVD or PPD s y s t e m undergo p roces se s l i k e e x c i t a t i o n , d i s s o c i a t i o n and format ion of r e a c t i v e i n t e r m e d i a t e s p e c i e s r e s u l t i n g i n a s o l i d s u b s t a n c e d e p o s i t e d on a s u b s t r a t e . In the d e p o s i t i o n , two d i f f e r e n t p r o c e s s e s t a k e p l a c e : i) homogeneous r e a c t i o n in the gas phase , of which the mechanism and the k i n e t i c s were c o n s i d e r e d and compared f o r b o t h s y s t e m s w i t h r e s p e c t t o v a r i a b l e s such as gas mix tu re , f low, p r e s s u r e , t empe ra tu r e , power i n p u t and l o c a t i o n of the s u b s t r a t e in the r e a c t o r . i i ) h e t e r o g e n e o u s r e a c t i o n be tween t h e gas p a r t i c l e s and t h e s o l i d s u b s t r a t e l e a d i n g t o c l u s t e r i n g and n u c l e a t i o n phenomena. The s u r f a c e a c t i v i t y r e a c t i o n s for both CVD and PPD systems were c o n s i d e r e d .

THE EVOLUTION OF STRONG SHOCK WAVES PRODUCED BY A TRAPEZOIDAL LASER PULSE A. Loeb , S. E l i e z e r , A. Z i g l e r , B. Arad, A. L u d m i r s k y , Y. G a z i t , S. J a c k e l , A. D. Krumbein , J . L. B o r o w i t z , I . G i l a t h , H. Szichman and M. Givon

An a n a l y t i c hydrodynamic model for t h e formation and decay of s t r o n g shock waves (0.1-10 TPa) was d e r i v e d [ 1 ] , A tempora l t r a p e z o i d a l p r e s s u r e p r o f i l e a p p l i e d t o t h e t a r g e t s u r f a c e was used a s an i n i t i a l c o n d i t i o n . T h i s m o d e l , which p e r m i t s t h e c a l c u l a t i o n of t h e v a r i o u s shock f r o n t p a r a m e t e r s , was a p p l i e d t o l a s e r - g e n e r a t e d shock w a v e s . R e a r - s u r f a c e l u m i n o s i t y m e a s u r e m e n t s of shock waves g e n e r a t e d by t r a p e z o i d a l l a s e r p u l s e s were made us ing a s t r e a k camera [ 2 ] . Unloading of the f r ee s u r f a c e i n t o vacuum was i n d i c a t e d . A n o t h e r , more s e n s i t i v e , d i a g n o s t i c method c o n s i s t s of n o r m a l l y r e f l e c t i n g 2(1w l a s e r l i g h t from t h e r e a r s u r f a c e of t he t a r g e t . With t h i s b a c k l i g h t i n g t echn ique , l a t e r a l energy t r a n s p o r t was d e t e c t e d for a 40 ym foca l s p o t . REFERENCES:

[ 1 ] Loeb, A. and E l i e z e r , S . , Phys . F l u i d s 2 8 , 1196 (1985) . [ 2 ] Arad, B. e t a l . , Plasma Phys . 26 , 845 (1984) .

LASER GENERATED SHOCKWAVE VELOCITY MEASUREMENTS USING A VISIBLE BACKLIGHTING TECHNIQUE [ 1 ]

A. Z i g l e r , A. L u d m i r s k y , S . J a c k e l , M. G i v o n , I . G i l a t h , Y. G a z i t , A. Borowitz , M. K i s h i n e v s k i and B. Arad

A h i g h l y s e n s i t i v e t e c h n i q u e f o r m e a s u r i n g h i g h power l a s e r g e n e r a t e d Shockwave v e l o c i t i e s was d e v e l o p e d . Shockwave v e l o c i t i e s

44

produced by pressures as low as 50 GPa were measured, with no limit in the

pressure that can be measured on the high pressure side.

REFERENCE:

[13 Z i g l e r , A., Ludmirsky , A., J a c k e l , S., Givon , M., G i l a t h , I . , Gazi t , Y., Borowitz, A., K i s h i n e v s k i , M. and Arad, B., J . Phys. , E 19, 309 (1986).

SPALLATION AND DYNAMIC FRACTURE AS AN EFFECT OF LASER INDUCED SHOCK WAVES D. Salzmann, I . G i l a t h , Y. P a i s s , M. D a r i e l , L. Kornb l i t * and T. Bar^Noy

The s t r a i n r a t e of 107 s e c - 1 a t t a i n a b l e in l a s e r induced shock waves p r e s e n t s a new parameter domain in t h e i n v e s t i g a t i o n of m a t e r i a l b e h a v i o r . The aim of t he p r e s e n t work was t o i n v e s t i g a t e m a t e r i a l b e h a v i o r under h igh p r e s s u r e and h i g h s t r a i n r a t e l a s e r i n d u c e d shock w a v e s , t o s t u d y t h e d i f f e r e n t s t a g e s of m a t e r i a l f a i l u r e , such a s i n t e r n a l c r a c k f o r m a t i o n , s p a l l a t i o n and t a r g e t p e r f o r a t i o n , a s w e l l a s t o measure t h e pa ramete r s of v a r i o u s m a t e r i a l s under dynamic c o n d i t i o n s .

The e x p e r i m e n t a l f a c i l i t i e s i n c l u d e a s i n g l e beam Ndtg las s l a s e r s y s t e m . The s y s t e m p a r a m e t e r s a r e : 1-20 n s e c p u l s e w i d t h , f o c a l s p o t d i a m e t e r i n t h e r a n g e 100 ym t o s e v e r a l mm, l a s e r i r r a d i a n c e s of 101° r- i o 1 3 w/cm2. The o b t a i n a b l e p r e s s u r e s in m e t a l s a r e of t h e o rde r of 0.1 - 1.5 Mbar.

The e x p e r i m e n t a l e f f o r t i s b a c k e d by a 1-D h y d r o d y n a m i c code s i m u l a t i n g t h e e v o l u t i o n of l a s e r gene ra t ed plasma and shock waves.

Some p r e l i m i n a r y exper iments were performed on a s e r i e s of m e t a l s t o e s t a b l i s h t h e d i f f e r e n t s t a g e s of m a t e r i a l f a i l u r e from t h r e s h o l d t o p e r f o r a t i o n .

Ben-Gurion U n i v e r s i t y of the Negev, Beer - Sheva

H5

MULTIPLE-PASS AMPLIFIERS FOR HIGH-POWER LASER SYSTEMS S. J a c k e l , R. L a l l u z , M. G ivon , A. Ludmi r sky , A. Z e n t n e r , S. E l i e z e r , J . L. Borowitz , B. Arad, A. Z i g l e r and Y. Gazi t

M u l t i p l e - p a s s a m p l i f i e r s were conf igured from Nd:g lass rods us ing p o l a r i z a t i o n and a n g u l a r c o u p l i n g t e c h n i q u e s . Very h i g h g a i n (>600) , s i n g l e beam, t r i p l e - p a s s b o o s t e r s t a g e s and high gain (30 or 15) s i n g l e or double beam double pass a m p l i f i e r s were combined to c o n s t r u c t a very c o s t -e f f e c t i v e , high-power (50 GW) p u l s e d l a s e r system. These t echn iques were a l s o e f f e c t i v e l y a p p l i e d to s m a l l e r compact high r e p e t i t i o n - r a t e systems.

INTERFERENCE BETWEEN BROADENED SIDEBANDS OF A PULSED AMPLIFIED PHASE-MODULATED

CW DYE LASER (PAPMOL) [ 1 ] H. Lotem, M. Amit, S . Lavi , Y. L i ran and G. Erez

The s p e c t r u m of a n a r r o w band CW l a s e r may be expanded by t h e g e n e r a t i o n of e q u a l l y spaced s idebands which a r e phase l i n k e d v i a e x t e r n a l phase m o d u l a t i o n . The s p e c t r a l p r o f i l e of t h e s i d e b a n d s d e p e n d s on t h e modula t ion index. Pu l sed a m p l i f i c a t i o n of the modulated CW l a s e r broadens each s ideband and, t hus , i n t e r f e r e n c e between the s idebands i s in t roduced . In t h i s work, i t was t h e o r e t i c a l l y and e x p e r i m e n t a l l y shown t h a t t h e r e s u l t i n g spectrum i s a func t ion of t h a t i n t e r f e r e n c e , and depends on the m o d u l a t i o n f r e q u e n c y fi , t h e a m p l i f i e r p u l s e w i d t h T, and t h e p h a s e r e l a t i o n between the p e r i o d i c a l r e f r a c t i v e index in the modulator and the a m p l i f i e r p u l s e . Var ious s p e c t r a l l i n e s h a p e s could be genera ted by va r y ing the modulat ion parameters and the a m p l i f i e r p u l s e t iming in r e l a t i o n t o t he modulator phase. REFERENCE: [1] Lotem, H., Amit , M., L a v i , S. , L i r a n , Y. and E r e z , G., J . Opt. Soc .

Am. B, i n p r e s s .

LOW TEMPERATURE KINETIC STUDIES OF THE HF CHEMICAL LASER

D. Chuchem, K. Waichman and Y. Kal isky The d e l a y time between the i n i t i a t i n g p u l s e and the development of

the l a s e r emission for v a r i o u s v i b r a t i o n a l t r a n s i t i o n s in the HF chemical l a s e r was measu red . The measu remen t s were pe r fo rmed fo r v a r i o u s low t e m p e r a t u r e s by v a r y i n g t h e Mach number and s t a g n a t i o n p r e s s u r e i n a supe r son ic - f l ow premixed, e l e c t r i c - d i s c h a r g e l a s e r . The d i r e c t measurement of the time development of the l a s i n g P-branch t r a n s i t i o n s a s a func t ion of t h e t e m p e r a t u r e was compared t o a t h e o r e t i c a l model which y i e l d s i n f o r m a t i o n on t h e F + H- r e a c t i o n r a t e s . The r e l a t i v e t e m p e r a t u r e -dependent peak power in the P-branch l i n e s for the p u l s e d HF l a s e r a t 115K and 158K were a l s o measured and ana lyzed .

60 W 2.06 ym Ho3+:YLF LASER [1 ] H. Lotem, J . Kagan, D. Sag ie and L. A. Levin

A c r y o g e n i c CW 2.06 um holmium l a s e r was d e v e l o p e d . The l a s i n g

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medium i s a 5 x 70 mm YLF c r y s t a l rod (doped w i t h h i g h c o n c e n t r a t i o n s of Er^ + and Tm^+ and a f r a c t i o n of a p e r c e n t of Ho^+) o r i e n t e d w i t h t h e c r y s t a l o p t i c a l a x i s n o r m a l t o t h e rod a x i s . O p t i c a l pumping of t h e rod was p e r f o r m e d in a g o l d - c o a t e d e l l i p t i c a l c a v i t y by a l i n e a r 1000 W incandescen t lamp. The cryogenic c o o l i n g was ob ta ined by a h igh flow r a t e ( -1 .5 g a l l o n / m i n ) of p r e s s u r i z e d l i q u i d n i t r o g e n a l o n g t h e l a s e r r od main ta ined by a cryogenic pump. The maximum power of 60 W (with H.5% s l o p e and M% t o t a l e f f i c i e n c y ) was ob ta ined by o p e r a t i n g the lamp a t 1500 W. As e x p e c t e d , t h e l a s e r i s l i n e a r l y p o l a r i z e d a l o n g t h e o p t i c a x i s . L i n e a r d e p e n d e n c e of t h e o u t p u t power on i n p u t was o b s e r v e d up t o t h e maximum power. Energy d i s s i p a t i o n m e a s u r e m e n t s pe r fo rmed on YLF showed an unexpec ted ly low rod the rma l load. With a Ho:YAG c r y s t a l , 37 W ou tpu t was o b t a i n e d unde r t h e same l a s e r c o n d i t i o n s , b u t w i t h c l e a r s a t u r a t i o n beg inn ing a t 1000 W pumping power.

The l a s e r s t r u c t u r e i s in p r i n c i p l e s i m i l a r t o t h a t of a CW Nd:YAG l a s e r in which an incandescen t lamp pumps the rod in an e l l i p t i c a l g o l d -c o a t e d c a v i t y . A s p e c i a l f e a t u r e of t h e holmium l a s e r i s i t s c r y o g e n i c o p e r a t i o n a l t empera tu re ; i n s t ead of us ing water as t he c o o l a n t , p r e s s u r i z e d LNp, which f lows a l o n g the l a s e r rod a t a r a t e of 1.6 l i t e r / m i n , c o o l s t h e a c t i v e medium. For the rmal i n s u l a t i o n the l a s e r head i s evacua t ed and AR-coa ted . IR qua r t z windows e n c l o s e the vacuum chamber [ 2 ] .

The maximum l a s e r power o f -60 W ( w i t h a 4.5? s l o p e and H% t o t a l e f f i c i e n c y ) was o b t a i n e d w i t h a pump power of 1500 W. T h i s i s t w i c e t h e power r e p o r t e d p r e v i o u s l y for Ho-.YLF l a s e r s . The °t3Ho:YLF rods t r i e d he re were t a k e n from two c r y s t a l b o u l e s of s i m i l a r n o m i n a l c o m p o s i t i o n . The sample which g i v e s the bes t r e s u l t s shows l i n e a r dependence of t he o u t p u t power on input with no power s a t u r a t i o n up to t he maximum pump power t r i e d . For c o m p a r i s o n , s l i g h t s a t u r a t i o n i s s e e n in a d i f f e r e n t YLF s a m p l e and s t r o n g e r s a t u r a t i o n i s observed in YAG.

The l i n e a r dependence of output power v s . pumping power and t h e low rod the rmal load in Ho:YLF show t h a t s c a l i n g up the l a s e r power i s p o s s i b l e to a t l e a s t t he 100 W l i m i t us ing a s i n g l e rod o s c i l l a t o r . REFERENCES: [ 1 ] Lotem, H., Kagan, J . , S a g i e , D. and L e v i n , L. A., J . Opt . Soc . Am. A2_,

P107 (1985) . [ 2 ] Many d e t a i l s of t h e l a s e r d e s i g n a r e based on u n p u b l i s h e d work of

A. L i n z , H. P. J e n s s e n , M. Model and C. S. Nalman.

2.1 MICRON HOLMIUM LASER [1 ]

H. Lotem, J . Kagan, D. Sag ie and L. A. Levin A CW, 2.1 micron, c ryogenic holmium l a s e r was deve loped . The l a s e r

g a i n medium i s a YAG c r y s t a l doped w i t h h i g h c o n c e n t r a t i o n s o f Er^ + and Tm^+ and low Ho^+ c o n c e n t r a t i o n . The 2.1 mic ron l a s e r t r a n s i t i o n o c c u r s be tween t h e I y l e v e l and t h e I g g round s t a t e m u l t i p l e t o f Ho3 + . High laser efficiency, over 2%, is achievable in this laser due to the strong and broad-band absorption of the Er/Tm ions, which efficiently transfer

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t h e i r e x c i t a t i o n t o t he Ho^+ i o n s , and due to the c ryogen ic c o o l i n g of t he system t o o b t a i n an e f f e c t i v e f o u r - l e v e l l a s e r system.

The s t r u c t u r e of t he l a s e r i s s i m i l a r t o t h a t of h igh energy Nd/YAG l a s e r s . O p t i c a l pumping i s performed in a g o l d - c o a t e d c y l i n d r i c a l c a v i t y by a l i n e a r lamp. C r y o g e n i c c o o l i n g i s o b t a i n e d by a h i g h f l o w r a t e o f p r e s s u r i z e d l i q u i d n i t r o g e n a l o n g the rod. A s p e c i a l pump ma in t a in s t he c l o s e d loop flow. Due t o t e m p e r a t u r e - g r a d i e n t changes in t he rod the l a s e r o p t i c a l c a v i t y shoul ' i be p e r i o d i c a l l y a l i g n e d dur ing l a s e r o p e r a t i o n . Thus f a r , a s t a b l e 10 W l a s e r o u t p u t h a s been a c h i e v e d u s i n g a 1 kW pump lamp wi th an uncoated 70x5 mm rod . REFERENCE: [1 ] Lotem, H., Kagan, J . , S a g i e , D. and L e v i n , L. A., i n : M e e t i n g of

O p t i c a l Engineer ing in I s r a e l , 4 th , T e l - A v i v , May 1985, Assoc i a t i on of Engineers in I s r a e l , p. 36.

APERTURE AVERAGED COVARIANCE FUNCTION OF TWO-FREQUENCY LIGHT INTENSITY FLUCTUATIONS IN STRONG TURBULENCE Z. A z a r , H. M. L o e b e n s t e i n , G. Appe lbaum, E. A z o u l a y , U. H a l a v e e , M. Tamir and M. Tur

The i n f l u e n c e of a p e r t u r e a v e r a g i n g on the two-frequency i n t e n s i t y c o v a r i a n c e f u n c t i o n was e x p e r i m e n t a l l y d e t e r m i n e d f o r two c o l l i n e a r , a p p r o x i m a t e l y s p h e r i c a l 1.064^ and 0.6328u beams, p r o p a g a t i n g t h r o u g h s t r o n g l y s c a t t e r i n g a tmospher ic p a t h s . I t was e s t a b l i s h e d t h a t in s p i t e of t h e s i z a b l e w a v e l e n g t h s e p a r a t i o n and t h e l o n g p r o p a g a t i o n p a t h s , t h e c o r r e l a t i o n c o e f f i c i e n t be tween t h e w a v e l e n g t h s a t t a i n e d f a i r l y h i g h v a l u e s , even for s m a l l a p e r t u r e s . The expe r imen ta l r e s u l t s o n l y app ly t o wide enough beams, where beam wander e f f e c t s can be n e g l e c t e d .

The e x p e r i m e n t a l s e t u p h a s been d e s c r i b e d e l s e w h e r e [ 1 ] , The t r a n s m i t t e r o p t i c s g e n e r a t e s two c o l l i n e a r beams wi th a common d ive rgence of 3 mrad. A f t e r t h e s u b t r a c t i o n of t h e dc b a c k g r o u n d l e v e l s , t h e c o r r e c t e d d i g i t i z e d r eco rds of t he r e c e i v e d s i g n a l s were used t o compute t he v a r i a n c e (o j ) a t each wave l eng th a s w e l l as the s p e c t r a l c o v a r i a n c e func t ion [Cov(^ 1 , ^ ) ] , and the i n t e n s i t y s p e c t r a l c o r r e l a t i o n c o e f f i c i e n t p( \ • \ ^ \ » ^ * S i m u l t a n e o u s m o n i t o r i n g of t h e i n d e x - o f - r e f r a c t i o n s t r u c t u r e c o n s t a n t , C n , p r o d u c e d v a l u e s on t h e o r d e r o f Cn

2 - 10 3 - i o ~ ' 1 m~2 3 t h a t correspond to s t r o n g t u r b u l e n c e c o n d i t i o n s .

F igure 1 shows p(A. o6'^0 63^ a s a f u n c t i o n o f t n e receiver aperture D for two ranges. As expected [2,3], i t is a monotonically increasing function, and interestingly enough, attains fairly high values even for relatively small aperture sizes.

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0.8

S 0 . 6 -o

~ 0.4

a. 0 . 2 -— L= 1300 m

1.0

0 . 8 -

0 . 6 -o

C Q4

0 2 -

-

1 1

1

L= 3250 m

i i i

r 1

i

•" &

1 10 20

D(mm) 30 10 20

D(mm) 30

F i g . 1 The e x p e r i m e n t a l c o r r e l a t i o n c o e f f i c i e n t for L = 1300m,3250m, a s a func t ion of t he a p e r t u r e s i z e . The da t a p o i n t s r e p r e s e n t a v e r a g e s ove r 5"8 measurements, and the r e s u l t i n g s t anda rd d e v i a t i o n s a r e i n d i c a t e d by the b a r s .

REFERENCES:

[1 ] Aza r , Z., L o e b e n s t e i n , H.M., Appelbaum, G., A z o u l a y , E., H a l a v e e , U.f T a m i r , M. and Tur , M., A p p l . Opt. 2M, 2401 (1985).

[ 2 ] Homstad, G. E., S t r o h b e h n , J . W., B e r g e r , R. H. and Heneghan, J . M., J . Opt. Soc . Am. 6±, 162 ( W O .

C3] Dunphy, J . R. and Kerr , J . R., J . Opt. Soc. Am. 63 , 981 (1973) .

THE EFFECT OF APERTURE AVERAGING ON THE STATISTICS OF LASER POWER FLUCTUATIONS IN STRONG TURBULENCE E. Azoulay, Z. Azar and M. Tur

The s t a t i s t i c s of i n t e n s i t y s c i n t i l l a t i o n s of a l a s e r beam, p r o p a g a t i n g through a tmospher ic t u r b u l e n c e , has been e x t e n s i v e l y s t u d i e d in r e c e n t y e a r s fo r p o i n t r e c e i v e r s . Whi le t h e l o g - n o r m a l d i s t r i b u t i o n i s f a i r l y a d e q u a t e i n t h e weak t u r b u l e n c e r e g i m e [ 1 , 2 ] , q u i t e a few d i s t r i b u t i o n s have been sugges ted t o d e s c r i b e s t r o n g o p t i c a l s c i n t i l l a t i o n s from the Rayle igh d i s t r i b u t i o n (for very s t r o n g t u r b u l e n c e ) , through the r -K- and t h e r e c e n t l y in t roduced I - K d i s t r i b u t i o n s [ 2 - 6 ] . Most p r a c t i c a l a p p l i c a t i o n s , h o w e v e r , u s e d e t e c t o r s w i t h f i n i t e a p e r t u r e s , r a t h e r t h a n p o i n t r e c e i v e r s , and the s t a t i s t i c s of the a p e r t u r e - a v e r a g e d s c i n t i l l a t i o n s i s v i t a l for system a n a l y s i s .

I f I ( r ) i s t h e p o i n t s p a t i a l i n t e n s i t y d i s t r i b u t i o n o v e r t h e a p e r t u r e , t o e v a l u a t e t h e p r o b a b i l i t y d i s t r i b u t i o n f u n c t i o n of t h e a p e r t u r e - a v e r a g e d power one n e e d s t o know t h e m u l t i - d i m e n s i o n a l j o i n t

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p r o b a b i l i t y d i s t r i b u t i o n of I ( r ) up to order n, a long with the d i f f e r e n t c o r r e l a t i o n s d i s t a n c e s , and have the c a p a b i l i t y of c a r r y i n g out the required n-dimensional integrat ion. These two requirements render any such i n t e g r a t i o n a t tempt v i r t u a l l y imposs ib le . We used an empirical , Monte-Car lo approach to e v a l u a t e the p r o b a b i l i t y d i s t r ibu t ion function of the aperture-averaged power. The r e s u l t s of t h i s simulation compare favorably with our experimental r e s u l t s .

Figure 2 depicts the r e s u l t s obtained for aperture diameters in the range 2 - 18 mm. The r e s u l t s show g radua l d e p a r t u r e from the po in t receiver d i s t r ibu t ion function toward the log-normal d i s t r ibu t ion function, so that for ra ther small apertures one can use the log-normal function as a good approximation even in the strong turbulence regime.

Figure 3 depicts the measured values of the same normalized moments, for purposes of comparison with theore t i ca l models; we a l so show the log-normal and K-distr ibution curves for these normalized moments. Many of the

2

Fig. 2 Computed values of the aperture averaged normalized moments <In>/n for n = 3~5 as a funct ion of /^. The cont inuous l i n e s i n d i c a t e the moments obtained from log-normally d i s t r ibu ted in tens i ty f luc tua t ions . The broken l i ne s indicate moments from redis t r ibuted intensi ty f luc tua t ions .

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c

I05

JO4

I03

c / N »—» V

I02

I01

10°

x D = o D = A D = a D =

-pr-Imm / • JS 5mm /N . x yT 20mm / n = 5 S / 40mm / N v / / /

*% / / I X • ' X x o / /

/ °X f X /

/ •,« / v / v / "t/ / / / > / * / /

/ A / / x*x ' / A / i ° / ^ / / / ° ^ o **? ^ -

A / ° 8 / ^ S \

L •/&' X ^ ~-

Iff If 1 1 1 1 1

Fig. 3 Measured values of the aperture averaged normalized th i rd , fourth, and fifth moments are compared with the values predicted by the various model dstributions, having the same normalized second moments as the experimental data. The continuous lines indicate the moments expected from log-normally distributed intensity fluctuations and apply to a l l values of normalized second moment. The broken l ines indicate moments expected from K-d i s t r ibu ted f luc tua t ions and apply to values of the normalized second moment greater than 2.

data obtained with the point receiver (D = 1 mm) co r r e l a t e well with previously published resu l t s [1,5], while the data obtained with the larger aperture size (D = Ho mm) remain log-normally distributed for a l l values of the mean-square fluctuations that were obtained in the experiment.

In summary, the proposed method enabled us to show that under strong scattering conditions the point receiver power s t a t i s t i c s is considerably d i f f e r e n t from the a p e r t u r e averaged power d i s t r i bu t ion function.

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M o r e o v e r , t h e a p e r t u r e - a v e r a g e d i n t e n s i t y d i s t r i b u t i o n f u n c t i o n can be adequa te ly d e s c r i b e d by the l o g m o r m a l d i s t r i b u t i o n f u n c t i o n . REFERENCES: [1 ] F r i e d , D. L. e t a l . , J . Opt. Soc. Am. 57 , 787 (1967) . [2 ] Fan t e , R., P r o c . IEEE 6^, 1669 (1975) . [3] Jakeman, E . , J . Phys. A. J_3, 31 (1980) . [1] P h i l l i p s , R. L. and Andrews, L. C. , J . Opt. Soc. Am. J±, 1 ^ 0 (1981) . [5] Par ry , G. and Pusey, P . N . , J . Opt. Soc. Am. £ 9 , 796 (1979) . [6] P h i l l i p s , R. L. and Andrews, L. C , J . Opt. Soc. Am. 2 , 160 (1985) .

PERFORMANCE OF A PULSE POSITION MODULATION ATMOSPHERIC COMMUNICATION CHANNEL

Y. Gur and Y. Weissman In t h i s work the performance of a p u l s e p o s i t i o n modula t ion (PPM)

a tmospher ic o p t i c a l communication channe l was e v a l u a t e d t a k i n g i n t o account t u r b u l e n c e e f f e c t s . This performance was found t o be comparable w i th t h a t of an on-of f keying (00K) format wi th opt imized demodulat ion.

PPM i s an a t t r a c t i v e t e c h n i q u e fo r t h e enhancemen t o f t h e d a t a t r a n s m i s s i o n r a t e c a p a b i l i t y of a t m o s p h e r i c o p t i c a l c o m m u n i c a t i o n s y s t e m s [ 1 ] . The d e m o d u l a t i o n of t h e PPM fo rma t d o e s n o t r e q u i r e a t h r e s h o l d , and t h e r e f o r e i t a u t o m a t i c a l l y a d a p t s i t s e l f t o t h e random f l u c t u a t i o n s in the s i g n a l l e v e l imposed by the a tmospher ic t u r b u l e n c e .

The f i x e d t h r e s h o l d d e m o d u l a t i o n of t h e more c o n v e n t i o n a l (00K) s i g n a l i s c o n s i d e r a b l y e a s i e r t o implement, bu t i t s v u l n e r a b i l i t y to s i g n a l f l u c t u a t i o n s makes i t a lmos t u s e l e s s for a tmospher ic a p p l i c a t i o n s . Schemes f o r i m p r o v i n g t h e 00K d e m o d u l a t i o n p e r f o r m a n c e i n a t u r b u l e n t channel [2 ,3 ] r e q u i r e c o n s i d e r a b l e p r o c e s s i n g , comparable a t l e a s t t o t h a t r e q u i r e d for t h e demodula t ion of the PPM s i g n a l .

We h a v e q u a n t i t a t i v e l y e v a l u a t e d t h e p e r f o r m a n c e of a MAP PPM decoder [1] t a k i n g i n t o account s i g n a l d e t e r i o r a t i o n due t o the p resence of t u r b u l e n c e . Two c a s e s were cons ide red : a) a photon counting rece iver with Poisson s t a t i s t i c s , b) d i r e c t d e t e c t i o n wi th an a v a l a n c h e p h o t o d i o d e d e t e c t o r o p e r a t i n g w i t h

high background and s i g n a l l e v e l s and Gaussian s t a t i s t i c s . The performance of t h e channe l i s q u a n t i f i e d by t h e p r o b a b i l i t y of

e r r o r per t r a n s m i t t e d b i t [ 1 ] . Th i s q u a n t i t y has been e v a l u a t e d n u m e r i c a l l y f o r s e v e r a l s e t s of p a r a m e t e r s of i n t e r e s t f o r s a t e l l i t e - t e r r e s t r i a l o p t i c a l l i n k s . I t was found t h a t the PPM r e c e i v e r performance i s comparable to t h a t of the a d a p t i v e t h r e s h o l d t e c h n i q u e s . REFERENCES: [1] G a g l i a r d i , R. M. and Karp, S., O p t i c a l Communications (Wiley, New York,

1976) . [2] C h u r n s i d e , J . H. and M c l n t y r e , C. M., A p p l . Opt . 1 6 , 2669 (1977) . [ 3 ] R o s e n b e r g , S. and T e i c h , M. C , A p p l . Opt . V2, 2625 (1973) .

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ANGULAR RESOLUTION OF AN OPTICAL RECEIVER IN A TURBULENT ATMOSPHERE FOR A WIDE RANGE OF THE APERTURE DIAMETERS I . Las t and Y. Weissman

An o p t i c a l wave p r o p a g a t i n g t h r o u g h a t u r b u l e n t a t m o s p h e r e h a s a d i s t o r t e d w a v e f r o n t due t o d i f f e r e n t p h a s e s h i f t s a l o n g d i f f e r e n t p ropaga t ion p a t h s . This d i s t o r t i o n randomly changes t h e a n g l e of a r r i v a l , b o t h i n s p a c e and i n t i m e , and i n c r e a s e s t h e e f f e c t i v e s p o t s i z e of t h e f o c u s e d beam. The t h e o r y of t h e l i g h t wave d i s t o r t i o n by a t u r b u l e n t a t m o s p h e r e was p r e s e n t e d by T a t a r s k i [ 1 ] . T h i s t h e o r y was used f o r t h e study of t h e a n g l e of a r r i v a l f l u c t u a t i o n s in numerous s t u d i e s , mainly for l i m i t e d i n t e r v a l s of t h e a p e r t u r e d iamete r . The aim of t he p r e s e n t work was t o o b t a i n the exp re s s ion for t he a n g l e of a r r i v a l v a r i a n c e for a wide range of a p e r t u r e d i ame te r s .

The c o r r e l a t i o n func t ion of the a n g l e of a r r i v a l i s expressed by the d e r i v a t i v e s of t h e s t r u c t u r e func t ion of t h e phase . The s t r u c t u r e func t ion Ds i s known f o r t h r e e i n t e r v a l s of t h e i n t e r p o i n t d i s t a n c e p : p << £ 0 , &Q « p « p F , P F « P << LQ, where iQ and LQ a r e r e s p e c t i v e l y t h e i n n e r and o u t e r s c a l e s of t h e t u r b u l e n c e and Pp i s t h e r a d i u s of t h e f i r s t F r e s n e l zone [ 2 ] . Using t he func t ions D s , one o b t a i n s t h e e x p r e s s i o n s for the c o r r e l a t i o n f u n c t i o n s which a r e v a l i d for t he i n t e r v a l s quoted above. These e x p r e s s i o n s were f i t t e d by an a n a l y t i c a l i n t e r p o l a t i o n f u n c t i o n

B . (p ) = B o

2 2

a + s2)7/6 + a2\ sV/6 (D

5 a = U F + 3 n 2 ) / ( l + n 2 ) , n = a 2 / 4 <2>

B = A C 2 x r 1 / 3 (3) o n o

where

C = P/*0 . h = PF/*0 (1)

o i s a p ropaga t ion parameter , C^ i s a t u r b u l e n c e s t r u c t u r e c o n s t a n t , x i s t he p ropaga t ion d i s t a n c e , A = 1.225, b1 = 0.661, b 2 = 0.996.

For a long exposure , t he v a r i a n c e i s < a > = BQ. The s h o r t exposure variance is < (a) >, where the upper l i ne stands for the aperture averaging.

The r e s u l t s of ca l cu l a t ions for lQ = 5 mm are presented in Fig. H, together with the Fried's angle of a r r i v a l variance [33 and the d i f f rac t ion a n g l e . The d i f f e r e n c e between the long and s h o r t exposure a n g l e s of

56

|06t- I I 1 I I lO"12 10-" I0"10 I 0 ' 9 • I0" 8

C * X ( c m " 3 )

Fig . H Angle of a r r i v a l v a r i a n c e as a func t ion of the product C^x. lQ = 5 mm,

Pp = 10 cm. The numbers on the c u r v e s s tand for a p e r t u r e d i ame te r s . angle of a r r i v a l v a r i a n c e , long exposure

*• angle of a r r i v a l v a r i a n c e , s h o r t exposure — • — d i f f r a c t i o n l i m i t s of angu la r r e s o l u t i o n

F r i e d ' s angle of a r r i v a l v a r i a n c e , long exposure

a r r i v a l i s s i g n i f i c a n t when the a p e r t u r e d iameter i s s m a l l e r than -10 l0. For very s m a l l d iamete r s (D < 1 cm) the d i f f r a c t i o n broading becomes more impor tan t than the t u r b u l e n c e f l u c t u a t i o n s . REFERENCES: [ 1 ] T a t a r s k i , V . I . , The E f f e c t s of t h e T u r b u l e n t Atmosphere on Wave

Propaga t ion , I s r a e l Program for S c i e n t i f i c T r a n s l a t i o n s , J e r u s a l e m , 1971.

[ 2 ] Fan te , R .L . , Proc . IEEE £ 3 , 1669 (1975). [ 3 ] F r i ed , D.L. , J . Opt. Soc . Am. 55, 1127 (1965) .

LEVEL-CROSSING PROBABILITY IN AN ATMOSPHERIC COMMUNICATION LINK IN THE CASE OF STRONG TURBULENCE

I . L a s t , M. Tamir, U. Halavee and E. Azoulay I n o r d e r t o d e s i g n l a s e r communica t i on c h a n n e l s s u i t a b l e f o r

o p e r a t i o n i n t he t u r b u l e n t atmosphere one has to know the l e v e l - c r o s s i n g p r o b a b i l i t i e s . P r e v i o u s l y , L a s t and Tamir used t h e m u l t i - d i m e n s i o n a l d i s t r i b u t i o n to c a l c u l a t e l e v e l - c r o s s i n g p r o b a b i l i t i e s for the r e a l i s t i c non-Markov l o g - i r r a d i a n c e [ 1 ] . La ter the m u l t i - d i m e n s i o n a l r e s u l t s were

57

f i t t e d by an a n a l y t i c a l expression which i s convenient for p r ac t i c a l purposes [2 ] . However, the considerat ion was r e s t r i c t e d to a weak turbulence only, i.e. to a turbulence with a small propagation parameter a2 < 0.6.

In the surface- to-surface communication l i nk the l i g h t beam propagates in the low atmospheric layer, usually with intense turbulence. Most often the propagation parameter a? i s much l a rge r than 1 when the distance exceeds 1 km so i t i s important to consider a l so the strong turbulence case (25 < CT2 < 100) [33-

In the strong turbulence case the correlation function is described by a complicated function with a long t a i l . Because of the nonexponential character of t h i s function the s t a t i s t i c s of the propagating pulses i s described by a non-Markov process. The resul ts of calculations show that in the case of strong turbulence and strong in te rpu l se cor re la t ion the multi-dimensional level-crossing probabili ty d i f fe r s s i gn i f i c an t l y from that obtained by the two-dimensional (Markov) approach.

The multi-dimensional level--erossing probabili t ies were f i t ted by an analytical expression

P = 1 - (1 - P l ) f n (1)

f = d - c12)Y+ ec12d r- c 1 2 ) 3 / 5 (2)

where p., i s a s ing le -pu l se l eve l - c ross ing probabi l i ty , n i s the number of p u l s e s , and C j 2 i s t h e c o r r e l a t i o n c o e f f i c i e n t between two ne ighbor ing p u l s e s . The parameters y and 3 were found by optimizing the mean square devia t ion of (1) from the "exact" multi-dimensional va lues

Y = 1.18 + 0.31 5 + 0.01452 (3)

6 - [1 + 76C|/(1 + 0.4£ 2 ) ] (0 .32 - 6 / ° 2 + 0.1925 + 0.03352 W

5= ln(0.5/p.,) (5)

C.p i s the cor re la t ion coeff ic ient between the edges of the sampling time. REFERENCES: [1] Las t , I . and Tamir, M., i n : Proceedings of the Third I n t e r n a t i o n a l

Conference on Infrared Physics, Zurich, 1984, p. 796; and in: IA-1U01, 1983, p. 9.

[2] Last , I . , Halavee, U. and Tamir, M. , in : IA-1412, 1985, p. 14. [3] Las t , I . , Tamir, M., Ha lavee , U. and Azoulay, E., Appl. Opt. (1986), in

p ress .

58

APERTURE AVERAGED LEVEL-CROSSING IN AN ATMOSPHERIC COMMUNICATION LINK I . Las t and E. Azoulay

The e f f e c t i v e n e s s o f a l a s e r communication l i n k in t he a tmosphere i s r e s t r i c t e d by i n t e n s i t y f l u c t u a t i o n s r e s u l t i n g from atmosphere t u r b u l e n c e . The l e v e l - c r o s s i n g p rocess in the sequence of l i g h t p u l s e s a f f e c t e d by the t u r b u l e n c e was s t u d i e d r e c e n t l y a s a n o n - M a r k o v p r o c e s s C l~33 . The c o n s i d e r a t i o n was r e s t r i c t e d , h o w e v e r , t o t h e c a s e o f a p o i n t d e t e c t o r . The p r e s e n t s tudy d e a l s wi th t he l e v e l - c r o s s i n g problem for d e t e c t o r s wi th n o n - z e r o a p e r t u r e . The p r o b l e m of t h e a v e r a g i n g of t h e l i g h t i n t e n s i t y o v e r an a p e r t u r e i s c o m p l i c a t e d b e c a u s e of t h e c o r r e l a t i o n b e t w e e n d i f f e r e n t p u l s e s . In o r d e r t o s o l v e t h i s p r o b l e m n u m e r i c a l l y we u s e d a d i s c r e t e a p e r t u r e model.

According to the f rozen t u r b u l e n t flow h y p o t h e s i s t he i n t e n s i t y of t h e i n c i d e n t l i g h t changes a l o n g the d i r e c t i o n of the wind v e l o c i t y on ly . In the d i s c r e t e model the a p e r t u r e i s d i v i d e d i n t o m s e c t i o n s . The t o t a l f l u x pass ing th rough the a p e r t u r e i s determined as a sum

M W i = I h*** ( 1 )

m=l

where i i s t h e p u l s e index, I^ m i s the l i g h t i n t e n s i t y in t h e c e n t e r of the s e c t i o n m, and Sm i s t h e a r e a of t h e s e c t i o n . The v a l u e s I^m a r e cons ide red as s e p a r a t e p u l s e s which a r e c o r r e l a t e d one wi th t h e o t h e r . The 1^ s t a t i s t i c s can now be c o n s i d e r e d i n t h e same way a s i n t h e p o i n t a p e r t u r e case. [ 2 , 3 3 . As t h e a p e r t u r e r a d i u s i n c r e a s e s t h e l e v e l ^ c r o s s i n g p r o b a b i l i t y for independent p u l s e s o b v i o u s l y dec reases due t o a v e r a g i n g . This dec rease i s much s t e e p e r when t h e r e i s a c o r r e l a t i o n between p u l s e s . REFERENCES:

[ 1 ] L a s t , I . , Tamir, M. i n : IA-HI04, 1983, p . 9 . [ 2 ] L a s t , I . , Halavee , U., and Tamir, M., i n : IA-1405, p . 14. [ 3 ] L a s t , I . , T a m i r , M., H a l a v e e , U. and A z o u l a y , E., A p p l . Opt . ( 1 9 8 6 ) , i n

p r e s s .

59

ESR STUDIES IN SEMICONDUCTOR-INSULATOR TWO-FLAYER STRUCTURES* J. T. Suss, V. Zevin , A. Zerael and S. Rotter

A novel appl ica t ion of the e lec t ron spin resonance (ESR) technique was demonst ra ted: ESR can be used as a t o o l for the i n v e s t i g a t i o n of the e l e c t r i c a l proper t ies of a semiconducting layer. Such a layer , placed on an insu la t ing subst ra te , d i s t o r t s the ESR lineshape of the impurit ies in the substra te . The d i s to r t ion depends on the conductivi ty and thickness of the l a y e r . The t h e o r e t i c a l l i n e s h a p e was ob ta ined by c a l c u l a t i n g the su r f ace impedance of the two- l aye r s t r u c t u r e by s o l v i n g the Maxwell equations together with the magnetization equation for appropriate boundary conditions. When the lineshape i s known, the asymmetry parameter (the A/B r a t i o of the l ine) can be used for measuring the conductivi ty of the layer. The usefulness of t h i s method was demonstrated for the semiconductors Ge and InSb on a ruby (Al20-,:Cr3+) s u b s t r a t e , us ing the ESR l i n e s h a p e of the

impurit ies. The possible extention to other two-layer systems, such a s m e t a l - m e t a l , m e t a l - s e m i c o n d u c t o r and m e t a l - i n s u l a t o r was a l s o considered.

MAGNETIC STRUCTURES IN THE TERNARY RM2X2 COMPOUNDS (R = Gd to Tm; M = Fe, Co, Ni , or Cu; X = S i or Ge) [ 1 ] H. Pinto, M. Melamud, M. Kuznietz and H. Shaked

Neutron-diffraction measurements were performed on p o l y c r y s t a l l i n e samples of 13 different compounds of the type RM2X2 (R, a heavy lanthanide from Gd to Tm; M, the 3d e lement Fe, Co, Ni, or Cu; X, Si or Ge), a t room tempera ture and a t low tempera tu res . The c r y s t a l l o g r a p h i c s t r u c t u r e of these compounds belongs to the te t ragonal space group 14/mmm ( D J ^ ) . I t was found t h a t these compounds, paramagnet ic a t room tempera tu re , undergo a t r a n s i t i o n to an t i fe r romagne t i sm a t low tempera tu res . The t r a n s i t i o n t empera tu res and most of the magnetic s t ruc tu re s were determined. Below the t r a n s i t i o n t empera tu re , magnetic o rde r ing was found on ly on the R sub l a t t i c e , and no magnetic ordering was detected on the M sub l a t t i c e . The magnetic l a t t i c e s were found to be characterized by propagation vectors of k = (0,0,1) in the c o b a l t compounds i n v e s t i g a t e d (TbCo2Si2 , HoCo2Si2, DyCo2Ge2, and ErCo2Ge2), k = (^.O.ls) in the copper compounds i n v e s t i g a t e d (TbCu2Si2 , HoCu2Si2 , TbCu2e2 , and HoCu2Ge2), and incommensurate k = (0,0,0,76) in HoNi2Ge2 (unsolved incommensurate in other n ickel compounds and in i ron compounds). Together with p r e v i o u s l y pub l i shed r e s u l t s on other RM2X2 compounds, the magnetic l a t t i c e i s found to vary with M and be almost invar iant to R. REFERENCE: [1] P i n t o , H., Melamud, M., Kuznietz , M. and Shaked, H., Phys. Rev. B 3J.,

508 (1985).

This work was supported by the Fund for Basic Research admin i s t e r ed by the I s rae l Academy of Sciences and Humanities Hebrew University, Jerusalem

63

NEUTRON DIFFRACTION INVESTIGATION OF COMMENSURATE AND INCOMMENSURATE PHASES IN UAs1f_„Sev SINGLE CRYSTALS* M. Kuznie tz , P . B u r l e t , J . Rossat-Mignod and 0 . Vogt

UAs o r d e r s a t TN = 123 t IK in the s 5 n g l e - k t y p e - I a n t i f e r r o m a g n e t i c (AF) s t r u c t u r e ( + - + - ) and u n d e r g o e s a t r a n s i t i o n a t TQ = 63 t 1 K t o t h e d o u b l e - k t y p e - I A AF s t r u c t u r e ( + + — ) , b o t h t r a n s i t i o n s b e i n g f i r s t o rde r [ 1 ] . S t u d i e s of s i n g l e c r y s t a l s of s o l i d s o l u t i o n s formed between UAs and f e r r o m a g n e t i c USe ( b o t h N a C l - t y p e ) by m a g n e t i z a t i o n [ 2 ] and a c s u s c e p t i b i l i t y [ 3 ] s u g g e s t e d t h e magne t i c phase diagram of t he UAs^_xSex

s y s t e m i n z e r o f i e l d (H = 0 ) . We i n v e s t i g a t e d s e v e r a l UAs^_xSe s i n g l e c r y s t a l s by n e u t r o n d i f f r a c t i o n a t H = 0 a n d f o u n d f o r x < 0 .50 incommensurate phases j u s t below the second-o rde r t r a n s i t i o n a t T^ and down t o a f i r s t - o r d e r i n c o m m e n s u r a t e - c o m m e n s u r a t e t r a n s i t i o n a t T I C . The k -v a l u e of t h e w a v e v e c t o r k = [ 0 , 0 , k ] a t TN was found t o v a r y c o n t i n u o u s l y from k = 0.642 f o r x = 0 . 0 3 , t h r o u g h 0.619 f o r x = 0 . 0 5 , 0.550 f o r x = 0 , 1 0 , 0.475 fo r x = 0 .20 , and 0.414 f o r x = 0 .25 , and 0.387 f o r x = 0.30 t o 0.224 fo r x = 0 .40 . I n t h e l a t t e r c a s e k - 2 / 9 , i n d e p e n d e n t of t e m p e r a t u r e down t o 4.2K, i n d i c a t i n g a f e r r i m a g n e t i c 5 + , 4 - s t r u c t u r e . In d e c r e a s i n g t e m p e r a t u r e s t h e k - v a l u e v a r i e s s l i g h t l y and c o n t i n u o u s l y t o w a r d t h e commensura te v a l u e of t h e p h a s e be low T I C , e x c e p t f o r x = 0.25 and x = 0.30 where t h i s v a r i a t i o n i s s t r o n g e r and smeared o u t on approaching the type-IA phase. A magnetic phase diagram of t he UAs.]_xSex

system ( a t H = 0) based on our r e s u l t s was proposed. REFERENCES: [1 ] R o s s a t - M i g n o d , J . , B u r l e t , P. , B a r t h o l i n , H., T c h a p o u t i a n , R.,

V o g t , 0 . , V e t t i e r , C. and Lagn ie r , R., Phys ica 102B, 177 (1980). [2] Vogt, 0 . and B a r t h o l i n , H. , J . Magn. Magn. Mater. 29 , 291 (1982) . [3] B a r t h o l i n , H., B r e a n d o n , C , T c h a p o u t i a n , R. and V o g t , 0 . , J . Phys . 4j>,

1183 (1984) .

MODIFICATION OF THE MAGNETIC STRUCTURE OF UAs - APPEARANCE OF AN

INCOMMENSURATE PHASE BELOW TN IN UAsQ g y S e Q ^ , , STUDIED BY NEUTRON DIFFRACTION FROM A SINGLE CRYSTAL+[1] M. Kuznie tz , P . B u r l e t , J . Rossat-Mignod and 0. Vogt

The m a g n e t i c s t r u c t u r e of UAsQ aySeQ 0 , was s t u d i e d by n e u t r o n d i f f r a c t i o n from a s i n g l e c r y s t a l in ze ro a p p l i e d magnetic f i e l d . I t was found t o be a n t i f e r r o m a g n e t i c , of t y p e - I A (+ + —) be low TQ = 75.6K and of t y p e - I (+-+-) above TQ. The t y p e - I p e r s i s t s t i l l T I C = 113.5K, w h i l e above i t and up to TN = 122K an incommensurate phase appea r s , t he reby modifying the magnetic s t r u c t u r e in pure UAs. The k~va lue of t he wavevec to r k ( a long c u b i c a x e s ) c h a n g e s from 0.642 a t TN t o 0.652 a t T I C . The t r a n s i t i o n s a t

This work was performed a t Centre d ' E t u d e s N u c l e a i r e s , Grenoble , France Cent re d 'E tudes N u c l e a i r e s , Grenoble, France ETH Zur i ch , Zu r i ch , Swi t ze r l and

64

TQ and TIC are first-order while the transition at TN is second-order. The ordered magnetic moment is 2.15 U

B a t T = H.2K; i t v a r i e s s m o o t h l y t o 1.95 VB a t T = 75.UK and d r o p s d r a s t i c a l l y t o 1.H7 VB a t T = 76K. REFERENCE: [ 1 ] K u z n i e t z , M., B u r l e t , P . , R o s s a t - M i g n o d , J . and V o g t , 0 . , S o l i d S t a t e

Commun. 55 , 1063 (1985) .

NEUTRON DIFFRACTION STUDY OF A U A s o g 5 S e 0 0 5 SINGLE CRYSTAL: DISAPPEARANCE OF THE TYPE-I ANTIFERROMAGNETIC STRUCTURE"1" N. Kuzn ie t z , P . B u r l e t , J . Rossat-Mignod and 0 . Vogt

A s i n g l e c r y s t a l o f UASQ o c S e g gc w a s s t u d i e d by n e u t r o n d i f f r a c t i o n . I t o r d e r s a t TN = 121.5K w i t h an i n c o m m e n s u r a t e p h a s e , c h a r a c t e r i z e d by a w a v e v e c t o r k = [ 0 0 k ] w i t h k(TN) = 0 .619 . On l o w e r i n g t h e t e m p e r a t u r e , two d i f f e r e n t t y p e s of m a g n e t i c b e h a v i o r a r e o b s e r v e d , a t t r i b u t e d t o two " p a r t s " of t h e c r y s t a l , e a c h c o n t a i n i n g s e v e r a l c r y s t a l l i t e s , h a v i n g v e r y c l o s e s e l e n i u m c o n t e n t , x. The " p a r t " w i t h lower x undergoes an incommensurate-commensurate t r a n s i t i o n a t TJQ - 106K t o t he t y p e - I a n t i f e r r o m a g n e t i c phase (+-+-) , wi th k(T I C ) = 0.596, fo l l owed by a t r a n s i t i o n a t TQ = 93K t o the type-IA a n t i f e r r o m a g n e t i c phase (++—). The " p a r t " wi th h igher x t r ans fo rms from the incommensurate phase d i r e c t l y t o t y p e - I A a t T I C = 103K w i t h k ( T I C ) = 0 .587. Both " p a r t s " d e t e r m i n e t h e c r i t i c a l c o m p o s i t i o n , x - 0 . 05 , f o r t h e d i s a p p e a r a n c e of t h e t y p e - I s t r u c t u r e i n t h e a r s e n i c - r i c h UAs-,_xSex s o l i d s o l u t i o n s . The m a g n e t i c p h a s e d i a g r a m in t h i s r e g i o n was e s t a b l i s h e d and compared w i t h p r e v i o u s v e r s i o n s .

NEUTRON DIFFRACTION STUDY OF A NpAs SINGLE CRYSTAL"1"

P. B u r l e t , S. Q u e z e l , M. K u z n i e t z , D. B o n n i s s e a u , J . R o s s a t - M i g n o d , J . C. S p i r l e t , J . Rebizant and 0 . Vogt

Neptunium monoarsenide (NpAs), wi th the NaCl- type c r y s t a l l o g r a p h i c o

s t r u c t u r e (a = 5.81 A), was p r e v i o u s l y found by m a g n e t i z a t i o n , Mossbauer e f f e c t , and powder neut ron d i f f r a c t i o n [1 ] t o o rde r a n t i f e r r o m a g n e t i c a l l y a t TN - 175K w i t h t h e C4+,1!-) s t r u c t u r e , and t o t r a n s f o r m a t T - 16OK t o a mixed t y p e - I - ( t + , H - ) p h a s e , b o t h p h a s e s accompan ied by a t e t r a g o n a l d i s t o r t i o n of t h e l a t t i c e [ 1 ] . At T - 1H2K NpAs was found t o u n d e r g o a f i r s t - o r d e r t r a n s i t i o n t o t h e t y p e - I a n t i f e r r o m a g n e t i c p h a s e ( + - + - ) , accompanied by a r e t u r n to cubic symmetry. The ordered magnetic moment was found t o be - 2 . 5 u B a t 4.2K and t o v a r y s m o o t h l y t h r o u g h a l l t h e t r a n s i t i o n s up to TN.

We i n v e s t i g a t e d a s i n g l e c r y s t a l of NpAs (-21 mg), p repared a t the

+ T h i s work was performed a t Cent re d'Etudes N u c l e a i r e s , Grenoble, France Cent re d 'E tudes N u c l e a i r e s , Grenoble, France ETH Zur ich , Zur i ch , Swi t ze r l and European I n s t i t u t e for Transuranium Elements , Ka r l s ruhe , West Germany

65

European Ins t i tu te for Transuranium Elements in Karlsruhe by the mineralization method, by neutron diffraction in zero applied magnetic field (H = 0). The measurements were made with the DN3 double-axis diffractometer, in the Siloe reactor at the Centre d'Etudes Nucleaires de Grenoble. The crystal was aligned with a vertical [110] axis. By performing reciprocal-space scans along the line from [110] to [111] at decreasing temperatures we found that NpAs orders at TN = 173K with an incommensurate phase characterized by a value k = 0.232 + 0.003 of the wavevector k" = [00k] at TN, varying to k = 0.236 ± 0.003 at T - 155K. The absence of third-order harmonics at this temperature is indicative of a (longitudinal) sine wave. NpAs undergoes a first-order transition at TIC = 1 5 1 4 K t o a commensura t e ( 4 + , 4 - ) p h a s e , w i t h k = 0.247 t 0.003 - 1 M , and wi th t h i r d - o r d e r harmonics , t he reduced i n t e n s i t i e s of which i n d i c a t e p a r t i a l squa r ing -up o n l y . NpAs undergoes a n o t h e r f i r s t - o r d e r t r a n s i t i o n a t TQ = 138K t o t h e commensu ra t e t y p e - I p h a s e (k = 1 ) . The t e m p e r a t u r e d e p e n d e n c e of t h e n u c l e a r [ 1 1 1 ] peak i n t e n s i t y i s c o m p a t i b l e w i t h t h e changes in e x t i n c t i o n due t o v a r i a t i o n in c r y s t a l l o g r a p h i c symmetry [ 1 ] ,

The neut ron d i f f r a c t i o n s tudy of a NpAs s i n g l e c r y s t a l a t H = 0 was extended t o f i n i t e magnetic f i e l d s and the r e s u l t s were t o be compared wi th those ob t a ined by magne t i za t ion [ 2 ] , REFERENCES: [1 ] A l d r e d , A. T., D u n l a p , B. D., H a r v e y , A. R., Lam, D. J . , L a n d e r , G. H.

and Muel le r , M. H. , Phys. Rev. B 9_, 3766 (1974) . [2 ] R e b i z a n t , J . , S p i r l e t , J . C , M a t t e n b e r g e r , K. and V o g t , 0 . , i n

Proceed ings of the I4emes Journees des A c t i n i d e s (Davos, S w i t z e r l a n d , 2 - 3 A p r i l 1984) , J . S c h o e n e s , Ed., ETH Z u r i c h , 1984 , pp. 17~23 .

THE MAGNETIC PHASE DIAGRAM OF THE UAs1 (_xSex SYSTEM IN ZERO MAGNETIC FIELD STUDIED BY NEUTRON DIFFRACTION FROM SINGLE CRYSTALS"1"

M. Kuznie tz , P . B u r l e t , J . Rossat-Mignod and 0 . Vogt UAs o r d e r s a t TM = 123 ± 1K in the s i n g l e - k t y p e - I a n t i f e r r o m a g n e t i c

s t r u c t u r e (+-+-) and undergoes a t r a n s i t i o n a t TQ = 63 + 1K t o the double~k t y p e - I A a n t i f e r r o m a g n e t i c s t r u c t u r e (++—) , t h e l a t t e r t r a n s i t i o n b e i n g accompanied by a jump in the o rde red magnetic moment from 1.9 vB t o 2.2 uB. Both t r a n s i t i o n s a r e f i r s t - o r d e r [ 1 ] . The i s o s t r u c t u r a l compound USe i s f e r r o m a g n e t i c [ 2 ] . S t u d i e s of s i n g l e c r y s t a l s of t h e UAs-USe s o l i d s o l u t i o n s ( a l l of NaCl- type) by magne t i za t ion [33 and a c - s u s c e p t i b i l i t y [ 4 ] s u g g e s t e d t h e m a g n e t i c p h a s e d i a g r a m of t h e UAs, Se s y s t e m i n z e r o a p p l i e d magnet ic f i e l d (H = 0) .

We s t u d i e d U A s i - xS e

x s i n g l e c r y s t a l s w i t h x = 0 . 0 3 , 0 .05 , 0 .10 , 0 .20 , 0 . 25 , 0 .30 , 0 .40, 0.50 by n e u t r o n d i f f r a c t i o n i n H = 0. A l l c r y s t a l s

This work was performed a t Cent re d 'E tudes N u c l e a i r e s , Grenoble, France Centre d 'E tudes N u c l e a i r e s , Grenoble, France ETH Zur ich , Zur i ch , S w i t z e r l a n d

66

with x ^ 0.10 order antlferromagnetieally. TN has a flat minimum of 122K at x = 0.05*0.10 and rises to 136K for x = 0.10. The crystal with x = 0.50 is ferromagnetic (k = 0), with TQ = 166K. Incommensurate phases exist for x < 0.50 below the second-order transition at TN down to a first-order incommensurate-commensurate transition at TJQ. The k-value of the wavevector k = [00k] at TN varies continuously and almost linearly with x, from k = 0.612 in x = 0.03 to k = 0.221 in x = 0.10 [5]. In the l a t t e r case k - 2/9, independent of temperature dcwn to 1.2K, indicating the locking-up to a commensurate phase; the appearance of third-order harmonics below T - 90K indicates the squaring-up into the (5+,1_) ferrimagnetic structure. On cooling the k-value in a l l compositions varies slightly and continuously toward the commensurate value of the phase below TIC e x°ept f ° r x = 0.25 and 0.30 where t h i s v a r i a t i o n i s s t r o n g e r and smeared o u t on a p p r o a c h i n g t h e t y p e - I A p h a s e (k = 0 .500) . T h i s p h a s e i s t h e commensura t e p h a s e f o r 0 .05<x<0.30. For x < 0.05 t y p e - I (k = 1) i s observed below T j C , and i t undergoes ano ther f i r s t - o r d e r t r a n s i t i o n a t T c , t o type- IA, accompanied by a moment jump, a s in pure UAs [ 1 ] , The ordered m a g n e t i c moment a t 1.2K d r o p s from 2.25 P B i n UAs t o 2 u g a t x = 0.10 and remains p r a c t i c a l l y t he same for x > 0.10. The magnetic phase diagram was proposed and compared with those sugges ted p r e v i o u s l y . REFERENCES: [1 ] R o s s a t - M i g n o d , J . , B u r l e t , P . , Q u e z e l , S. , V o g t , 0. and B a r t h o l i n , H.f

i n : C r y s t a l l i n e E l e c t r i c F i e l d E f f e c t s in f - E l e c t r o n Magnetism (Proc. 1 t h I n t . Conf., Wroclaw, P o l a n d , 1981) , R. P. G u e r t i n , W. S u s k i , Z. Z o l n i e r e k , E d s . , P l enum P r e s s , New York, 1982, p . 5 0 1 .

[2] Wedgwood, F. A. and K u z n i e t z , M., J . P h y s . C: S o l i d S t a t e Phys . 5_, 3012 (1972) .

[3] Vogt, 0 . and B a r t h o l i n , H. , J . Magn. Magn. Mater . 29 , 291 (1982) . [1] B a r t h o l i n , H., B r e a n d o n , C , T c h a p o u t i a n , R. and V o g t , 0 . , J . Phys . 1 5 ,

1183 (1981) . [5] K u z n i e t z , M.f B u r l e t , P . , R o s s a t - M i g n o d , J . and Vog t , 0 . , J . Magn.

Magn. Mater. 5 l~57 , 553 (1986) .

NEUTRON DIFFRACTION AND MAGNETIZATION STUDIES OF UPQ QQSQ 2Q SINGLE CRYSTALS: OBSERVATION OF SEVERAL INCOMMENSURATE AND FIELDrlNDUCED FERRIMAGNETIC PHASES* M. Kuznietz , P. B u r l e t , J . Rossat-Mignod , 0. Vogt and K. Mat tenberger

S i n g l e c r y s t a l s of UPQ g 0 S 0 20 w e r e studied by neutron diffraction and magnetization measurements. In zero applied magnetic f i e ld UPQ goso 20 o r d e r s a t T N = 90K with an incommensurate s t ruc tu re characterized by a wavevector k = [OkO] with a k-value ranging from 0.388 to 0.392 at TN. UPQ g0S0 2 0 undergoes a first-order transition at Tj = 81K

This work was performed at Centre d1Etudes Nucleaires, Grenoble, France Centre d'Etudes Nucleaires, Grenoble, France ETH Zurich, Zurich, Switzerland

67

to another incommensurate phase with a wider range of k~values: 0.3**5-0.362 at T = 84.8K. At TJC - 78K a first-order transit ion occurs to a commensurate phase with k = 1/3 corresponding almost to a full squaring of the (3+,3~) antiferromagnetic structure. At TQ = 42K another first-order transition to the commensurate type-IA antiferromagnetic phase (2+,2~) with k = 1/2 takes place. The application of magnetic f ields decreases Tjj, destroys the incommensurate phases and induces three ferrimagnetic phases with 2/5, 5/9 and 2/3 the full moment. The (H,T) magnetic phase diagram of UP0.80S0.20 w a s g iven .

MAGNETIC STRUCTURES OF HoFe 5 Al ? . A NEUTRON DIFFRACTION STUDY H. P i n t o , M. Melamud and H. Shaked

The fami ly of compounds RFecAl~ (R = r a r e e a r t h ) c r y s t a l l i z e in t he

T h M n ^ t y p e s t r u c t u r e . T h i s s t r u c t u r e b e l o n g s t o t h e t e t r a g o n a l s p a c e g r o u p I4/mmm w i t h R a t 2a and Fe or Al a t 8f , 8 i and 8 j p o s i t i o n s . Mossbauer spec t roscopy and magne t i za t i on measurements made by F e l n e r e t a l . [ 1 ] show the fo l lowing p r o p e r t i e s : a) A distribution of iron ions among the 3 s i tes where the iron in the 8i position does not order magnetically. b) The magnetic moments of the iron ions in 8j position are antiparallel to the ferromagnetic, R sub lattice. c) The iron s u b l a t t i c e in the 8f posi t ion orders as a canted antiferromagnet (Gx.Fy), the ferromagnetic component being parallel to the iron in 8j position. d) All the iron ions are randomly distributed with the Al ions in each of the s i t es 8f, 8i and 8j . These suggestions can be tested by neutron diffraction. In the present work neutron diffraction of HoFe,-Al~ and YFecAL-, was studied.

Table 1 Magnetic moments (u) of the Ho and Fe ions (in uB) for the four possible

ferromagnetic, Fy, structures

Ion

Ho

Fe at 8f

Fe at 8j

Total moment ****

9.7

-2.1

1.4

a

± 0.4

± 0.3

0*

± 1.3

Fy structures

#* b

9.9 ± 0.5

-1.5 ± 0.3

-1.5 + 0.3

2.1) + 1.6

*** c

9.1) ± 0.6

-2.7 + 0.5

+2.7 ± 0.5

1.3 ±1.6

d

9.6 ± 0.1)

-2.3 ± 0.5

0.8 + 1.2

1.2 + 2.1)

Not refined.

Constraint u(Fe) at 8f = u(Fe) at 8j.

***Constraint P(Fe) at 8f = -u(Fe) at 8j.

The total moment per formula unit reported by Felner et al. is 2.3 ug

68

Neutron ( ^ 2 . 4 A ) d i f f r a c t i o n p a t t e r n s of powder samples of the two compounds were t a k e n a t 300K and 4.2K. I n t h e 300K p a t t e r n s a b e t t e r f i t was o b t a i n e d a s s u m i n g t h a t t h e 8 f p o s i t i o n i s o c c u p i e d by t h e i r o n i o n s on ly . The remain ing i ron ions randomly occupy t he 8 j p o s i t i o n . Moreover, t h e 4.2K p a t t e r n of HoFerAl-r a g r e e s wi th the fe r romagnet ic o r d e r i n g of t he i ron s u b l a t t i c e s wi th t h e i r moments a n t i p a r a l l e l t o t he f e r romagne t i c Ho s u b l a t t i c e . In the ca se of YFecAl- t h e 4.2K and 300K p a t t e r n s a r e s i m i l a r , hence i n d i c a t i n g no o b s e r v a b l e long range magnet ic o r d e r i n g a t H.2K. The v a l u e s of t he magnetic moments i n uB for four p o s s i b l e magnet ic s t r u c t u r e s a r e g i v e n i n Table 1. REFERENCE: [ 1 ] F e l n e r , I . , Nowik, I . and Seh, M., J . Magn. Mater. 38 , 172 (1983)

NEUTRON DIFFRACTION STUDY OF HNCU-GIC, LOW TEMPERATURE STRUCTURE"1"

H. Shaked, M. Melamud, H. P i n t o , R. Hi t te rman and J . Faber J r . The compound HN0,-GIC e x h i b i t s an o r d e r - d i s o r d e r t r a n s i t i o n a t

-240K. I n a p r e v i o u s s t u d y a t t h e IRR-2 , s u p e r l a t t i c e r e f l e c t i o n s were obse rved a t low tempera ture [ 1 ] . The purpose of the p r e s e n t s tudy was t o e n l a r g e the scanning range and v e r i f y t he p r e v i o u s l y proposed l a t t i c e [ 1 ] . The s a m p l e ( s t a g e IV) was s e t i n t h e n e u t r o n beam w i t h i t s c a x i s a t 1 3 5 ° t o t he beam a x i s . Data were t aken a t room tempera tu re and a t 100K with t he d e t e c t o r s a r ranged in four banks as shown in Table 2.

Table 2 The a n g u l a r r a n g e and t h e c o r r e s p o n d i n g d e t e c t o r s "ID" i n t h e

t i m e - o f - f l i g h t experiment (GPPD) a t Argonne N a t i o n a l Labora tory

Angular r a n g e : 2 6 (deg)

85.10 to 94.90

140.13 to 155.60 -140.13 to -155.60

-76.86 to -94.90

Detector ID

69 - 88 109 ~ 112, 125 ~ 128, 6 2 - 4 8 1 0 8 - 1 0 5 , 92 - 89, 24 - 2 104 - 93, 68 - 49

Time of f l i gh t scans were obtained, one for each detector . Typical scans c o l l e c t e d with ID81 ( a t 20 - 90°) and ID61 (a t 29 = -90°) a re shown in Fig. 1. Scans taken with a neutron diffractometer at the IRR-2 are a l so shown for comparison. Changes in i n t e n s i t i e s were observed in the 00L scan upon c o o l i n g , but no new r e f l e c t i o n s were seen. In the HKO scan, on the o the r hand, new r e f l e c t i o n s emerge ( too weak to be seen in Fig. 1) upon c o o l i n g . Some of these r e f l e c t i o n s observed (not seen in Fig. 1) around S=0.6, are in f u l l agreement with those observed at the IRR-2 (Fig. 1). We plan to perform the following data ana lys i s :

This work was performed at Argonne National Laboratory, Argonne,IL, U.S.A. Argonne National Laboratory, Argonne, IL, U.S.A.

69

( i ) Scans, c o l l e c t e d from d e t e c t o r s in the 90° bank, w i l l be merged together in order to improve s t a t i s t i c s . The merged scan w i l l be used to determine the p e r i o d i c i t i e s of the in-plane ordering of HNCL. ( i i ) I n t e n s i t y contour maps w i l l be prepared for the four s e c t i o n s of rec iproca l space scanned by the present experiments. These maps w i l l be used to identify features charac ter iz ing the rearrangement in the stacking of graphite planes which takes place during the ordering t r a n s i t i o n s . REFERENCE: [1] Shaked, H., P i n t o , H., Melamud, M. and Aviram, I . , Atomkern. Ener.

Kerntech. >V*5, 824 (1984).

STATIC ELECTRIC FIELD IONIZATION OF SODIUM** [1] P. McNicholl , J . I v r i , J .-Y. Liu , T. Bergeman and H. J . Metcalf

Above the c l a s s i c a l s a d d l e p o i n t energy, the p h o t o i o n i z a t i o n spectrum of sodium atoms in an e l e c t r i c f i e l d c o n s i s t s of a continuum background p l u s resonances . The sodium ion core coup le s q u a s i - d i s c r e t e l e v e l s with con t inua , producing Fano l i n e s h a p e s [23 t y p i c a l l y c l o s e to hydrogen Stark energies. Their width i s proport ional to the core overlap, t h e r e f o r e dec reases as |m| or n i n c r e a s e s . Also , w i th in an n manifold , s t a t e s of l e a s t s l o p e a r e wides t . Where two or more hydrogenic l e v e l s cross, dramatic l ine narrowing or broadening occurs due to interference of the bound-continuum coup l ing terms. These c o n c l u s i o n s a re suppor ted by many ca l cu l a t i ons with WKB-QD theory [33, by experiment, and by ana ly t i c expressions modeling the WKB-QD r e s u l t s . REFERENCES: [13 McNichol l , P. , I v r i , J . , Liu, J.-Y., Bergeman, T. and Metcalf , H. J . ,

Bull . Am. Phys. Soc. 30, 750 (1985), Abstract DH12. [23 Fano, U., Phys. Rev. J_2j£, 1866 (1961). [33 Harmin, D. A., Phys. Rev. A 26, 1656 (1981).

INTERFERENCE NARROWING AT CROSSINGS OF SODIUM STARK RES0NANCES+[1] fc # fc £

J.nY. Liu , P. M c N i c h o l l , D. A. Harmin , J . I v r i , T. Bergeman and H. J. Metcalf*

We have observed a s t r i k i n g l i n e narrowing in the photoionization spectrum of sodium atoms in an e l e c t r i c f i e l d . At c r o s s i n g s of two r e l a t i v e l y broad resonances , one of them i s narrowed by 2 t o 3 o rde r s of magnitude as a r e s u l t of interference between the d i sc re te and continuum coupling amplitudes that mediate t he i r ionizat ion. The observat ions agree

This work was performed at the Sta te University of New York, Stony Brook, NY, U.S.A. This work was supported by the National Science Foundation

State University of New York, Stony Brook, NY, U.S.A.

70

q u a n t i t a t i v e l y w i t h WKB quantum-defect S ta rk theory and a l s o wi th a s imp le r model i n v o l v i n g two d i s c r e t e s t a t e s and two c o n t i n u a . REFERENCE: [1] L iu , J . -Y . , M c N i c h o l l , P . , Harmin, D. A., I v r i , J . , Bergeman, T. and

Metcalf , H. J . , Phys. Rev. L e t t . £ 5 , 189 (1985) .

SODIUM STARK PHOTOIOKIZATION LINE WIDTHS AND LEVEL CROSSING EFFECTS*"1" [ 1 ] xx xx

J . I v r i , T. Bergeman and H. J . Metcalf To s u r v e y i o n i z a t i o n w i d t h s of sodium S t a r k l e v e l s , we h a v e

p e r f o r m e d c a l c u l a t i o n s w i t h Harmin ' s WKB-QD t h e o r y [ 2 ] . Where d a t a i s a v a i l a b l e [ 3 1 , t h e r e i s good agreement w i t h experiment . Our c a l c u l a t i o n s , on s e l e c t e d l e v e l s n = 12 and 2 1 , mL = 0, 1 and 2 , extend from r o u g h l y the reg ion where a l e v e l moves above t he s a d d l e po in t energy (Egp) t o t he po in t a t which t he hydrogenic width dominates. The width he re i s due t o c o u p l i n g by the ion core between q u a s i - d i s c r e t e h y d r o g e n - l i k e l e v e l s and degenera te cont inua . Apart from e f f e c t s a t l e v e l c r o s s i n g s , t he core - induced width i n c r e a s e s s l o w l y above Egp, then l e v e l s off. At c r o s s i n g s , i n t e r f e r e n c e e f f e c t s can b r o a d e n or n a r r o w a l i n e . For mL = 2 a n t i c r o s s i n g s ( t h e coup l ing term i s n o r m a l l y l a r g e r than the widths) i n t e r f e r e n c e narrowing i s f r e q u e n t l y n e a r l y c o m p l e t e , l e a v i n g o n l y h y d r o g e n i c w i d t h s , wh ich a r e t y p i c a l l y o r d e r s of m a g n i t u d e s m a l l e r . Such s t a b i l i z e d s t a t e s could be used for e l e c t r i c f i e l d c a l i b r a t i o n to unprecedented p r e c i s i o n . REFERENCES: [1 ] I v r i , J . , Bergeman, T. and M e t c a l f , H. J . , B u l l . Am. Phys . Soc . 3 £ , 7^9

(1985) , Abs t r ac t DH6. [2] Harmin, D. A., Phys. Rev. A 25, 1656 (1982).

[3] Littman, M. et al., Phys. Rev. Lett. 37, 486 (1976).

Pb-SALT LASER LIGHT SOURCES IN THE LONG-WAVELENGTH RANGE [1]

S. Rotter

Some of the spec ia l features of the Pb-sa l t mater ia l s system which dese rve s p e c i a l a t t e n t i o n inc lude l a t t i c e matching c o n s i d e r a t i o n s , substrate preparation, l iqu id phase epitaxy from supercooled so lu t ions and surface passivat ion. La t t i ce matching of a mul t i layer heteros t ructure is important since a mismatch as small as Aa/a-vIO-^ causes many d is loca t ions and r e s u l t s in poor dev i ce performance and degrada t ion . A s p e c i a l mechanochemical, contac t less pol ish was developed to prevent any physical con tac t between the s u b s t r a t e sur face and even a so f t pad. Thus a bu lk l i ke qual i ty substrate without subsurface damage can be rout ine ly obtained. The l iqu id phase ep i t ax i a l growth for heterost ructure mul t i l ayers i s used

This work was performed at the State University of New York, Stony Brook, NY, U.S.A. This work was supported by the National Science Foundation

*State University of New York, Stony Brook, NY, U.S.A.

71

w i t h h i g h l y s u p e r s a t u r a t e d s o l u t i o n s t o enhance n u c l e a t i o n . The l a t t i c e matching was found to be q u i t e impor tan t dur ing both growth and d i s s o l u t i o n u n d e r n e a r e q u i l i b r i u m c o n d i t i o n s . A f l a t i n t e r f a c e can be e a s i l y s u s t a i n e d when the s o l i d i n e q u i l i b r i u m wi th t h e me l t i s l a t t i c e matched t o t h e s u b s t r a t e . Device emphasis was on a b u r i e d h e t e r o s t r u c t u r e i n j e c t i o n l a s e r which e x h i b i t e d a s t a b i l i z e d l o n g i t u d i n a l mode b e h a v i o r unde r CW o p e r a t i o n from 15K t o a b o v e 70K. L a s i n g power t r a n s f e r t o a mode 20_1)0 c a v i t y modes away was a t t r i b u t e d t o a " g r a t i n g " - l i k e i n f l u e n c e imposing an a d d i t i o n a l c o n s t r a i n t on t he l a s e r spectrum.

The n a t i v e p a s s i v a t i o n scheme s t u d i e d r e s u l t e d i n s u b s t a n t i a l improvement i n e l e c t r i c a l c h a r a c t e r i s t i c s , tin i n c r e a s e in the R0A product of p-n j u n c t i o n d e t e c t o r s of s m a l l a r e a d e v i c e s , and a d e c r e a s e of the J t h

of i n j e c t i o n l a s e r s a t low t e m p e r a t u r e s . REFERENCES:

[1 ] R o t t e r , S. i n : SPIE P r o c e e d i n g s , v o l . 5 8 7 , O p t i c a l F i b e r S o u r c e s and D e t e c t o r s , in p r e s s .

DETERMINATION OF IR RADIATION ATTENUATION IN CHALCOGENIDE GLASS FIBERS BY TUNABLE DIODE LASERS [ 1 ]

U. Lach i sh , A. B o r n s t e i n , S. R o t t e r , U. El-Hanany and L. Boehm L e a d - s a l t t u n a b l e d i o d e l a s e r s w e r e a p p l i e d t o measu re IR

a t t e n u a t i o n in AsjSe, c h a l c o g e n i d e g l a s s f i b e r s . The a t t e n u a t i o n cons t an t a t 10.5 um i s d e t e r m i n e d from t h e s l o p e of t h e IR t r a n s m i s s i o n t h r o u g h a f i b e r a s a f u n c t i o n o f i t s l e n g t h , and t h e s p e c t r a l d e p e n d e n c e o v e r t h e 10_13 um wave leng th r e g i o n i s ob ta ined by tun ing the IR l a s e r source . REFERENCE: [1 ] L a c h i s h , U., B o r n s t e i n , A., R o t t e r , S., E l - H a n a n y , U. and Boehm, L.,

I n f r a r e d Phys. (1986) , in p r e s s .

VALENCE BAND PLASMON EFFECTS ON LINE SHIFTS AND WIDTHS IN POSITRON PLANAR CHANNELING RADIATION M. S t r a u s s , P. Amendt , H.U. Rahman and N. Rostoker

The s p e c t r a l s h i f t s and w i d t h s of p o s i t r o n p l a n a r c h a n n e l e d r a d i a t i o n were dynamica l l y desc r ibed . The p resence of w e l l - d e f i n e d v a l e n c e e l e c t r o n c o l l e c t i v e o s c i l l a t i o n s or plasmons, as documented in e l e c t r o n -l o s s s p e c t r o s c o p y , was p r o p o s e d a s one mechanism f o r e x p e r i m e n t a l l y obse rved n e g a t i v e s h i f t s . A second q u a n t i z a t i o n formal ism was used a s t h e framework fo r t h e a n a l y s i s of t h e p l a smon e f f e c t on t h e r a d i a t i o n spectrum [ 1 ] . Q u a n t i t a t i v e comparison wi th the e x p e r i m e n t a l d a t a a t 55 MeV for diamond s i l i c o n and LiF i s i n d i c a t e d . REFERENCE:

[ 1 ] Amendt, P . , S t r a u s s , M., Rahman, H. U. and R o s t o k e r , N., Phys . Rev. A. 33, 839 (1986).

New York U n i v e r s i t y , NY, U.S.A. U n i v e r s i t y of C a l i f o r n i a , I r v i n e , CA, U.S.A.

72

THE MEASUREMENT OF ELECTRON NUMBER DENSITY BY THE SERIES LIMIT LINE MERGING

METHOD. REASSIGNMENT OF ALUMINUM 3D SERIES

Z. Goldbart

Elect ron number density measured by the se r i e s l imi t l i ne merging method depends upon the assignment of the upper l e v e l of the l a s t d i sce rn ib le l i n e . Aluminum nd D l e v e l s were ca l cu la t ed for n=11 to n=l9. Some s p e c t r a l l i n e s measured in r e c e n t yea r s were r e a s s i g n e d . Lower r e s u l t s for e l ec t ron number density, up to 8 fold, were estimated.

73

STRAIN INDUCED MARTENSITIC TRANSFORMATION IN RAPIDLY SOLIDIFIED Au-Cd RIBBONS J . Baram and Y. Gefen

R a p i d l y s o l i d i f i e d Au-50at .£Cd r i b b o n s were o b t a i n e d by m e l t -sp inn ing . In the a s - c a s t s t a t e a t room tempera tu re , the c r y s t a l l o g r a p h i c s t r u c t u r e of the r ibbons i s a mixture of t he hexagonal 8" m a r t e n s i t i c phase and t h e C s C l t y p e p a r e n t p h a s e . The r i b b o n s h a v e a v e r y f i n e m i c r o s t r u c t u r e , w i t h g r a i n s r a n g i n g i n s i z e from s u b m i c r o n up t o a few microns. The g r a i n s i z e v a r i e d from one s i d e of the r ibbons to the o t h e r , a l t h o u g h t h e t h i c k n e s s o f t h e r i b b o n s d id n o t exceed 10 m i c r o n s . E l e c t r i c a l r e s i s t i v i t y da t a , performed on 4 s u c c e s s i v e c o o l i n g and h e a t i n g c y c l e s , as w e l l as X-ray d i f f r a c t i o n da t a taken a t d i f f e r e n t t empera tu res dur ing the c o o l i n g and h e a t i n g c y c l e s , were ga thered from v a r i o u s r i b b o n s , a f t e r c a s t i n g , a t v a r i o u s t ime i n t e r v a l s , up to 32 days a f t e r c a s t i n g .

A l l specimens showed a d r a s t i c and anomalous i n c r e a s e in e l e c t r i c a l r e s i s t i v i t y d u r i n g t h e f i r s t h e a t i n g c y c l e . The Ms t e m p e r a t u r e , a s ob ta ined from the r e s i s t i v i t y change du r ing c o o l i n g , v a r i e d in a range of a b o u t 50°C (from -41 °C up t o +7°C) d u r i n g t h e 32 day a g i n g p e r i o d . The amount of p a r e n t phase p r e s e n t i n t h e r i b b o n s d e c r e a s e d s y s t e m a t i c a l l y a l o n g the aging time l apse . The expe r imen ta l r e s u l t s were e x p l a i n e d as a s t r a i n - i n d u c e d m a r t e n s i t i c t r a n s f o r m a t i o n of t h e r e s i d u a l p a r e n t phase, d u r i n g t h e a g i n g p e r i o d , due t o i n t e r n a l s t r a i n s p r o d u c e d by t h e t h e r m a l g r a d i e n t and by q u e n c h e d - i n d e f e c t s a t s a t u r a t i o n , f o l l o w i n g t h e u l t r a -r ap id s o l i d i f i c a t i o n .

BLISTERING IN COMMERCIAL ALUMINUM ALLOYS VIA H+ and Ar+ ION IMPLANTATION [1 ] A, Munitz, Z. Livne and I . Gertner

In o rder t o e v a l u a t e the performance of s t r u c t u r a l m a t e r i a l s exposed to i r r a d i a t i o n a t high f l u e n c e s one has to study t e s t samples i r r a d i a t e d to h i g h e r f l u e n c e s . Ion i m p l a n t a t i o n i s commonly used [ 2 - 4 ] t o s i m u l a t e r a d i a t i o n damage e f f e c t s . By us ing ion i m p l a n t a t i o n one can o b t a i n , w i th in s e v e r a l h o u r s , t h e damage s i m u l a t i o n of abou t 10 y e a r s of r e a c t o r o p e r a t i o n . A p r e l i m i n a r y s t u d y of H and Ar+ i on i m p l a n t a t i o n i n commercial A1-A5 and Al-6061 a l l o y s was performed. The ion i m p l a n t a t i o n was c a r r i e d out a t the Technion us ing a Van de Graaff a c c e l e r a t o r which i s c apab le of a c c e l e r a t i n g ions of gaseous e l emen t s , such as H and Ar , up to e n e r g i e s of 1 MeV. During the ion i m p l a n t a t i o n the specimens were cooled by l i q u i d n i t rogen . The i m p l a n t a t i o n c o n d i t i o n s a re summarized in Tab le 1.

The specimen topography was observed by scanning e l e c t r o n microscope ( P h i l i p s 505 SEM).

The major e f f e c t of t h e i o n i m p l a n t a t i o n was s u r f a c e b l i s t e r i n g . The b l i s t e r s i z e s r a n g e be tween 4Um and 120um. A t y p i c a l b l i s t e r i n g phenomenon i s seen in Fig. 1.

Ben-Gurion U n i v e r s i t y of the Negev, Beer-Sheva Technion - I s r a e l I n s t i t u t e of Technology, Haifa

77

Alloy

A1-A5

Al-6061

Ion

Ar+

Ar+

H+

H+

' Table 1

Ion implantation conditions

Ion implanted

energy (keV)

800

800

200

200

Implanted Penetration

dose (VCi) depth ( pm)

10n 0.5

1011 0.5

101' 1.8

2x103 1.8

Calculated

damage (dpa)

158.0

158

'1.5

0.9

Fig. 1 Secondary e l e c t r o n images demonstrating the b l i s t e r i n g phenomenon for Ar+ ions implanted a t 800 keV with a dose of a 10^uCi in commercial Al-115 (Mag: 573X).

REFERENCES:

[1] Munitz, A., Livne, Z. and Gertner, I., in: Trans. Nucl. Soc. Israel,

vol. 12, 1985, p. 108.

[2] Farrel, K. and Packan, N. H., Effects of Radiation on Materials, 11th

Cont. ASTM, STP 782, H. R. Brager and J. S. Perrin, Eds. American

Society for Testing and Materials, 1982, pp. 953 to 962.

[3] Packan, N. H., Farrell, K. and Striegler, J. 0., J. Nucl. Mater. 7j5 113

(1978)

[»]] Sommer, W. F., Philips, D. S., Green, W. V., Hobbs, L. W. and

Wert, C. A., J. Nucl. Mater. 114 267 (1983).

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MULTILAYERED COMPACT RIBBONS OBTAINED BY CENTRIFUGE MELT SPINNING G. Rosen , Y. Gefen and J . Baram

M u l t i l a y e r e d r ibbons hav ing good adherence between AlGe l a y e r s were ob t a ined wi th a c e n t r i f u g e m e l t sp inn ing machine (CMSM). The CMSM works as f o l l o w s . A c e n t r i f u g a l fo rce deve loped i n s i d e a s p i n n i n g c r u c i b l e e x p e l s t h e m o l t e n a l l o y o n t o t h e i n n e r s u r f a c e of a c o p p e r r i m , which i s i t s e l f r o t a t i n g in a d i r e c t i o n o p p o s i t e t o t h a t of t h e c r u c i b l e . The SEM e x a m i n a t i o n of t h e Al-51wt;£ Ge r i b b o n s showed m u t u a l a d h e r e n c e of t h e l a y e r s . Almost p e r f e c t c o n t i n u i t y was a c h i e v e d . F i g u r e 2 p r e s e n t s a g e n e r a l v iew of t h e s a m p l e s h o w i n g t h r e e l a y e r s : a, b and c. The mean t h i c k n e s s of t h e l a y e r s was m e a s u r e d : a = 31-8 urn, b = 23.55 ym and c = 33.8 um. L a y e r a was t h e one i n c o n t a c t w i t h t h e c o p p e r r i m .

F ig . 2 The m u l t i l a y e r e d Al-Ge r ibbon (Mag: 950X)

The m e a s u r e m e n t s of t h e i n t e r l a m e l l a r spac ing i n d i c a t e d e c r e a s i n g c o o l i n g r a t e (R) from l a y e r a t o l a y e r c. The c a l c u l a t e d v a l u e s a r e : R(a) = 7X101' °C s e c - 1 , R(b) = ' lx10 J | °C s e c " 1 and R(c) = 3 x 1 0 3 °C s e c " 1 . The d e c r e a s i n g c o o l i n g r a t e from l a y e r a to c i s p robab ly due to t he change i n t h e n a t u r e of t h e s u b s t r a t e , from c o p p e r r im f o r r i b b o n a, t o 60 um ( l a y e r s a and b) of Al-Ge for r ibbon c. REFERENCE:

[ 1 ] Rosen, G., Gefen, Y. and Baram, J . , J . M a t e r . S c i . L e t t . _ 1, 1258

(1985) .

THE INFLUENCE OF OUTGASSING ON THE PROPERTIES OF HOT ISOSTATICALLY PRESSED 301L STAINLESS STEEL

D. Dadon, 0 . Yeheskel and Y. Gefen In t h i s work the i n f l u e n c e of v a r i o u s o u t g a s s i n g t e m p e r a t u r e s and

vacuum d u r a t i o n s on the d e n s i t y and t e n s i l e p r o p e r t i e s of 30HL s t a i n l e s s

Ben-Gurion U n i v e r s i t y of the Negev, Beer - Sheva

79

s t e s l powder af ter hot i s o s t a t i c pressing (HIP) was studied. Powders were enc losed in low carbon s t e e l c o n t a i n e r s , 40 mm in diameter and 90 mm in height. The containers were f i l l e d under v ibra t ion.

The ou tgass ing t empera tu re s were 25°C, 150°C, 350°C, i»00°C and 600°C. The powder was evacua ted for v a r i o u s t imes from 0.5 t o 10 h. During outgassing the dynamic vacuum in the container was measured.

The c o n t a i n e r s were s e a l e d by welding a f t e r o u t g a s s i n g , and then densified by HIP. The HIP parameters were: temperature = 900°C, pressure = 1350 MPa, time = 90 min.

The r e s u l t s show an increase in density and t e n s i l e proper t ies with increasing outgassing temperature up to 100°C, and an increase in density and t ens i l e propert ies with increasing evacuation time, up to 2 h.

THE Pr*Ga SYSTEM IN THE 66.7-100 at? Ga RANGE [1] D. Dayan, G. Kimmel and J . Pelleg

R e i n v e s t i g a t i o n of t h e Pr-Ga sys t em by X- ray d i f f r a c t i o n , d i f f e r e n t i a l thermal ana lys i s , metallography, scanning e l ec t ron microscopy and diffusion couples es tab l i shed tha t gal l ium has a wide s o l i d s o l u b i l i t y range in PrGa2 (78 a t ? Ga) and t h a t PrGag, which forms p e r i t e c t i c a l l y a t 466 t 6°C, e x i s t s . REFERENCE: [1] Dayan, D., Kimmel, G. and P e l l e g , J. , J . Less-Common Met. 105, 1^9

(1985).

RECENT ADVANCES IN THE RARE EARTH-GALLIUM SYSTEMS (R-Ga) [1] # x

J. Pelleg , L. Zevin , G. Kimmel and D. Dayan

The rare earth (R) gallium systems are considered to be composed of

an assembly of structural units, which are divided into two regions by

RGa2, the congruently melting compound. These regions are referred to as

the R-rich and Ga~rich sides, respectively. Four compounds were detected

on the R-rich side of the systems. New compounds and a wide solubility of

Ga in RGa2 constitute the main features on the Ga-rich side. Two kinds of

ordering were detected, a positional and an orientational ordering. The

common crystallographic features of these recently detected compounds and

their interrelation were considered.

REFERENCE:

[1] P e l l e g , J . , Zev in , L., Kimmel, G. and Dayan, D., J . Less-Common Met. 110, 91 (1985).

THE INFLUENCE OF HEAT TREATMENTS ON SOME MECHANICAL PROPERTIES OF A"286

STEEL [1]

A. Raveh and G. Kimmel

The mechanical p r o p e r t i e s (hardness and s t r e n g t h ) of the heat r e s i s t i n g s t e e l A-286 were tes ted af ter various heat treatments intended to


80

ob ta in high s t r e n g t h . The r e s u l t s show the hardness t o be t h r e e t imes higher, and the strength two times higher, following the heat treatments. The opt imal c o n d i t i o n s for these hea t t r e a t m e n t s a re a n n e a l i n g for two hours at 98o°C, and aging for 16 hours at 700°C. REFERENCE: [1] Raveh, A. and Kimmel, G., NRCN(TN)-073, 1985, in Hebrew.

AUSTENITE INSTABILITY IN AUSTENITIC STEELS DUE TO HYDROGENATION [1]

H. Mathias

This study concentrates on hydrogen induced changes in commercial 301L, 316L and 310 austenitic stainless steels , as well as experimental austenitic TRIP steel . Hydrogen was introduced by cathodic charging at room temperature, followed immediately by either repeatedly applied X-ray diffraction techniques or continuous microscopic observation of hydrogen gas bubble formation in a glycerin layer covering the hydrogenated specimens. For comparison, an extensive investigation was performed on hydrogen-free specimens, with emphasis on thermo-mechanically induced martensitic phases. In a l l selected commercial austenitic steels, cathodic hydrogenation Induced the formation of an expanded FCC and a HCP phase, relat ive to the original Y~Pnase a n d t n e the rmo-mechan ica l ly induced martensi t ic £'-phase, respec t ive ly . An expanded FCC phase a l so formed in the experimental TRIP s t e e l , but no HCP phase was detected. Immediately af ter hydrogenation termination the expanded FCC and HCP phases began to c o n t r a c t , con t inuous ly and s i m u l t a n e o u s l y , with hydrogen gas r e l e a s e . During these e v e n t s , unexpanded a ' -mar tens i t e formed slowly in the 301L, 31 6L and TRIP s t e e l s , but not in the 310 s t e e l . In f a c t , a f t e r prolonged l a t t i c e re laxa t ion the f ina l products were found to be iden t i ca l to those p re sen t in the r e s p e c t i v e hydrogen-f ree s t e e l a f t e r low tempera ture deformation. These t echn iques and complementary s t u d i e s enabled us to f igu re out the t h i c k n e s s of the hydrogen-af fec ted sur face l a y e r , the hydrogen c o n c e n t r a t i o n v a l u e s and the q u a n t i t a t i v e determination of the austeni te decomposition products. REFERENCE; [1] Mathias , H., NRCN-549, 1985, in Hebrew and Ph.D. Thes i s , Technion,

I s r ae l I n s t i t u t e of Technology, Haifa, 1980.

C02 LASER WELDING APPLICATIONS V. Ram, E. Tsory, F. Bendec and G. Kohn

The use of the C02 l aser in metalworking, and espec ia l ly in welding, has c o n s i d e r a b l y inc reased dur ing the l a s t few y e a r s . I t has been 3hown t h a t i t i s p o s s i b l e to weld a lmost a l l m a t e r i a l s in a g r e a t range of thicknesses.

We are engaged in research on COg l a se r welding appl ica t ions . Some examples include: - 304L s t a i n l e s s s t e e l in the t h i c k n e s s range of 0.2 t o 1.5 mm has been

successful ly welded. The influence of the dif ferent welding parameters on the pool shape were invest igated.

81

- Cans made of maraging s t e e l and aluminum 6061 for t h e e l e c t r o n i c i n d u s t r y have been h e r m e t i c a l l y s e a l e d by C02 l a s e r weld ing . Weld p e n e t r a t i o n in t h e m a r a g i n g s t e e l was a b o u t 1 mm w h e r e a s t h e p e n e t r a t i o n i n t h e aluminum cans was 0 .5 mm.

- Z i r c a l o y 2 and z i r c a l o y 'J were t u b e - t o - t u b e and t u b e - t o - e n d cap welded for e n c a p s u l a t i o n of n u c l e a r f u e l .

- S p o t w e l d s were made on v e r y s m a l l 303 s t a i n l e s s s t e e l g e a r w h e e l s , w i thou t caus ing any damage to the t e e t h .

- S p o t w e l d s were a l s o made on s u r g i c a l t i t a n i u m n e e d l e s , i n which r a d i o a c t i v e m a t e r i a l was encapsu l a t ed , fo r use i n cancer t h e r a p y .

C02 LASER WELDABILITY OF ZIRCALOY-2 V. Ram, G. Kohn and A. S t e r n

S a t i s f a c t o r y C02 l a s e r w e l d i n g o f z i r c a l o y - 2 b e a d ~ o n - p l a t e s was deve loped . The we lds were f r ee of d e f e c t s and d u c t i l e . In comparison wi th TIG w e l d s t h e t e n s i l e s t r e n g t h was s l i g h t l y h i g h e r and t h e d u c t i l i t y s l i g h t l y lower. No Sn v a p o r i z a t i o n was observed . The c o r r o s i o n r e s i s t a n c e of t h e w e l d s was s i m i l a r t o t h a t of t h e p a r e n t m e t a l and TIG w e l d e d specimens. The l a s e r we lds made in t he open under a l o c a l s h i e l d were as good as TIG welds made in an i n e r t gas chamber.

The main advantages of the COp l a s e r welding of z i r c a l o y - 2 a r e : a) T h e r e i s no need fo r an i n e r t g a s chamber . A l o c a l s h i e l d i s

s u f f i c i e n t . b) The h igh welding speed enhances t he p roduc t ion r a t e . c) The l a s e r welds a r e d u c t i l e and c o r r o s i o n r e s i s t a n t .

THERMOTRANSPORT OF HYDROGEN IN Zr~2.5 wt? Nb ALLOY+

A. S t e r n , H. A. Kneis and G. C. Weatherly The h e a t of t r a n s p o r t f o r Z r - 2 . 5 vt% Nb a l l o y was i n v e s t i g a t e d .

S a m p l e s from p r e s s u r e t u b e s c o n t a i n i n g 30 -150 ppm h y d r o g e n were h e l d i n c i r c u m f e r e n t i a l and l o n g i t u d i n a l d i r e c t i o n s i n a t e m p e r a t u r e g r a d i e n t (~13°C/mm) for p e r i o d s of 15 t o 30 days. O p t i c a l microscopy and hydrogen a n a l y s i s d e m o n s t r a t e d t h a t h y d r o g e n m i g r a t e d t o t h e c o l d j u n c t i o n . Computer s i m u l a t i o n s were p e r f o r m e d t o s t u d y t h e e f f e c t s of t h e v a r i o u s e x p e r i m e n t a l p a r a m e t e r s on the hydrogen c o n c e n t r a t i o n p r o f i l e .

HYDROGEN DEPTH PROFILING IN Zr-2 .5*wt Nb ALL0Y+

* * A. S t e r n , D. Katamian and G. C. Weatherly

Hydrogen c o n c e n t r a t i o n p r o f i l e s near t h e s u r f a c e of hydrogen-charged Zr-2.5wt^ Nb samples were measured by u t i l i z i n g the ^ ( ^ N . c t y ) 1 ^ r e a c t i o n . The h y d r o g e n c o n c e n t r a t i o n was d e t e r m i n e d t o a d e p t h o f - 2 pm w i t h a

T h i s work was p e r f o r m e d a t t h e U n i v e r s i t y of T o r o n t o , T o r o n t o , O n t a r i o , Canada University of Toronto, Toronto, Ontario, Canada

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resolution of -10 nm by measuring the yield of the characteristic y~rays as a function of the 5N energy. All the samples exhibited a strong H surface peak. For specimens oxidized at U00°C, the hydrogen surface peak was followed by a sharp drop and a depleted zone which approximately corresponded in width to the oxide thickness. Immediately beneath t h i s depleted zone was a region enhanced in hydrogen which was followed by a constant H level region. The data demonstrate the oxygen-induced hydrogen segregation with the oxidation process.

HYDROGEN TRAPPING DUE TO VOLUME IMPERFECTIONS IN IRON BASED ALLOYS E. Abramov and D. Eliezer

Hydrogen t r a p p i n g in m e t a l s i s a phenomenon t h a t a f f e c t s both p h y s i c a l ( d i f f u s i o n mechan i sms , hydrogen s o l u b i l i t y , e t c . ) , and technological (hydrogen embritt lement, b l i s t e r i n g , etc.) proper t ies . This phenomenon has recen t ly been studied in tens ive ly , e spec i a l l y in iron based a l l o y s . The present work suggests a t heo re t i c a l model which helps understand the hydrogen trapping mechanism around volume imperfections in iron based alloys.

According to th i s model, the hydrogen atoms are a t t r ac ted towards the imperfections and trapped around them due to positive stresses (tensile s t r e s s f ield) which p r e v a i l around them. Based on t h i s modeling, the in te rac t ion energy between hydrogen atoms and the imperfections could be ca lcu la ted . Accurate est imations can a l so be made to determine the distribution of hydrogen concentration around the volume structural defect as a function of the distance from i ts face.

The following imperfections were considered: MnS inclus ions in s teel , incoherent part icles of TiC and helium bubbles in metal. Similarly, i t is poss ible to estimate the hydrogen trapping around other defects. However, we selected cases where experimental data i s a v a i l a b l e so that resul t s calculated by the suggested model can be verified. In addition, for purposes of i l l u s t r a t i o n , a fu l ly de ta i l ed ca l cu l a t i on of the interaction energy for the case of hydrogen trapping around helium bubbles was made. This case is of particular interest when considering structural mater ia ls for future fusion f a c i l i t i e s , from the aspects of both fuel balance (various hydrogen isotopes) and long-term res i s tance of these materials.

Based on the suggested model, we obtained a trapping energy of 0.76 eV/atom (73.6 kJ/g.atom), in good agreement with experiment.

The ca l cu la t ions performed for different volumetric s t r u c t u r a l defects allow failure prediction due to hydrogen embrittlement. This is done by using the so-called "cr i t ical concentration concept". According to th i s c r i t e r i o n mater ia l f a i l u r e occurs when Ch > Ck. (Ch is the hydrogen concentration at any cer ta in s i t e in the mater ia l , Ck i s the c r i t i c a l


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c o n c e n t r a t i o n a t t he same s i t e . ) Both Ch and Ck a r e i n f l u e n c e d by numerous p a r a m e t e r s , s u c h a s t e m p e r a t u r e , d e f e c t shape , coherence , m i c r o s t r u c t u r e and e x t e r n a l / i n t e r n a l s t r e s s e s . The a b i l i t y t o c a l c u l a t e t h e h y d r o g e n c o n c e n t r a t i o n a round i m p e r f e c t i o n s p e r m i t s t h e o r e t i c a l a n a l y s i s of t h e above mentioned pa ramete r s and f o r e c a s t of f a i l u r e .

CATHODIC PROTECTION OF STAINLESS STEEL IN NITRIC ACID CONTAINING OXIDIZING IONS

M. Ben-Haim N i t r i c a c i d i s a b a s i c raw m a t e r i a l i n a wide r a n g e of i n d u s t r i e s :

f e r t i l i z e r s , e x p l o s i v e s , p l a s t i c s and d y e s . The c o n s t r u c t i o n m a t e r i a l s commonly u t i l i z e d in t h i s c o r r o s i v e medium a re a u s t e n i t i c s t a i n l e s s s t e e l s . AISI 304 i s u sed a t low t e m p e r a t u r e s and c o n c e n t r a t i o n s ; w i t h more o x i d i z i n g s o l u t i o n s , h i g h chromium and n i c k e l s t a i n l e s s s t e e l s a r e emp loyed [ 1 ] . C a t h o d i c a l l y p r o t e c t e d AISI 316 s t a i n l e s s s t e e l was a l s o sugges ted fo r use in o x i d i z i n g media [2D.

The n i c k e l c o n t e n t i n s t a i n l e s s s t e e l s d o e s n o t l o w e r t h e a n o d i c k i n e t i c s of t h e s e a l l o y s in the p a s s i v e p o t e n t i a l range. Thus, the use of low c o s t f e r r i t i c s t a i n l e s s s t e e l s ( w i t h o u t n i c k e l ) seems a p p l i c a b l e in h i g h l y o x i d i z i n g c o n d i t i o n s , p r o v i d e d t h e s e a l l o y s w i l l be k e p t in t h e p a s s i v e p o t e n t i a l zone by app ly ing c a t h o d i c p r o t e c t i o n .

Experiments in which c a t h o d i c p r o t e c t i o n was a p p l i e d t o an AISI 130 f e r r i t i c s t a i n l e s s s t e e l were c a r r i e d out . The c o r r o s i v e medium was n i t r i c ac id (4.0 N) c o n t a i n i n g Ce ions , which were added in o rde r t o s i m u l a t e a h i g h l y o x i d i z i n g s o l u t i o n . The c o r r o s i o n p o t e n t i a l of t h e AISI 430 s t a i n l e s s s t e e l s p e c i m e n was t r a n s p a s s i v e ; 1.1 V v s . 3CE. The c o r r e s p o n d i n g c o r r o s i o n r a t e was 250 mdd. P r o t e c t i n g t h i s s p e c i m e n c a t h o d i c a l l y by keeping i t a t 0.9 V vs . SCE, lowered the c o r r o s i o n r a t e t o a n e g l i g i b l e v a l u e of l e s s than 1 mdd, and no c o r r o s i v e a t t a c k was d e t e c t e d by s u r f a c e examinat ion .

These r e s u l t s p rove the f e a s i b i l i t y of us ing low cos t c a t h o d i c a l l y p r o t e c t e d f e r r i t i c s t a i n l e s s s t e e l s , i n s t e a d of the expens ive h igh n i c k e l and chromium a u s t e n i t i c a l l o y s c u r r e n t l y in s e r v i c e . REFERENCES: [1D F o n t a n a , M. G. and Greene , N. D., C o r r o s i o n E n g i n e e r i n g , M c G r a w - H i l l ,

NY, 1967, p. 245~246. [2 ] Ben-Haim, M., M.Sc. T h e s i s , U n i v e r s i t y of M a n c h e s t e r , I n s t i t u t e of

Sc i ence and Technology, 1980.

IMPROVED ANODIC PASSIVATION OF RAPIDLY SOLIDIFIED Al-Cu RIBBONS [1D D. I t z a c k , J . Baram and Y. Gefen

R a p i d l y s o l i d i f i e d Al-Cu r i b b o n s of e u t e c t i c c o m p o s i t i o n were ob ta ined by m e l t s p i n n i n g . The mel t was c e n t r i p e t a l l y e j e c t e d from fused

Ben-Gurlon U n i v e r s i t y of the Negev, Beer-Sheva

84

s i l i c a c r u c i b l e s of v a r i o u s d i a m e t e r s . Two t y p e s of r i b b o n s were p o t e n t i o d y n a m i c a l l y t e s t e d i n a 3.5% NaCl s o l u t i o n . The f i r s t , ob ta ined t h r o u g h a 0.3 mm d i a m e t e r o r i f i c e , had an a s - c a s t g r a i n s i z e in t h e 1 micron range . The second type , obta ined through a 1 mm diameter o r i f i c e had g ra in s i z e t h a t ranged from 4-7 microns.

The anodic p o l a r i z a t i o n c u r v e of t he f i r s t type r ibbon shows lower p a s s i v a t i o n c u r r e n t d e n s i t y . The a n o d i c b e h a v i o r i n t h e p a s s i v a t i o n p o t e n t i a l range of both t ypes i s e s s e n t i a l l y d i f f e r e n t . An a c t i v e peak in t h e p a s s i v a t i o n range of the anodic p o l a r i z a t i o n cu rve was obse rved in the second type, as w e l l a s in t he master a l l o y , wh i l e in the f i r s t type t h i s a c t i v e peak was not observed . X-ray d i f f r a c t i o n r e v e a l e d t he e x i s t e n c e of c r y s t a l l i n e S i 0 2 (most p r o b a b l y t r y d i m i t e ) in t h e r i b b o n s of t h e f i r s t type . This may be the main f a c t o r a f f e c t i n g the anodic behav io r of t h e s e r i b b o n s i n t h e p a s s i v a t i o n p o t e n t i a l r a n g e . The p r e s e n c e of SiO^ i s e x p l a i n e d as a r e s u l t of e r o s i o n - c o r r o s i o n of t h e c r u c i b l e due t o t he h igh v e l o c i t y s t ream of the m e l t through t h e narrow o r i f i c e . REFERENCE: [1 ] I t z a c k , D. , Baram, J . and Gefen, Y., J . Mater . S c i . L e t t . 4_ 445 (1985) .

JOINING OF ALUMINUM PLATES BY EPOXY RESIN. I I I . EFFECT OF STORAGE DURATION UP TO 52 MONTHS ON THE SPECIMENS [ 1 ] A. Raveh, B. Herrmann, D. Marouani and E. Rabinovi tz

P l a t e s of aluminum type 2024 were s u r f a c e - t r e a t e d , j o i n e d by epoxy r e s i n ( t y p e s c o t c h c a s t ) and s t o r e d f o r up t o 52 mon ths . F r a c t o g r a p h s of t h e a d h e s i o n s u r f a c e s were examined by o p t i c a l m i c r o s c o p y , a f t e r t h e specimens were t e s t e d for shear s t r e n g t h . The mode of the f a i l u r e and the adhesion s t r e n g t h were compared with those of specimens s to red for s h o r t e r p e r i o d s (24 and 36 months). The cont inued p o l y m e r i z a t i o n of t he r e s i n was e x p r e s s e d a s an i n c r e a s e i n a d h e s i o n s t r e n g t h . A l a r g e r p r o p o r t i o n of specimens, compared to t h o s e t e s t e d a f t e r a s h o r t e r s t o r a g e pe r iod , showed lower s t r e n g t h v a l u e s . The r e a s o n fo r t h e s e r e s u l t s i s t h e c o n t i n u e d development of f a i l u r e in the t r e a t e d f i lm on the aluminum s u r f a c e , t h a t i s t he weakening of the i n t e r m e d i a t e f i lm. REFERENCE: [1 ] Raveh , A., Herrmann, B. , M a r o u a n i , D. and R a b i n o v i t z , E., NRCN-56O,

1985, in Hebrew.

CARBON/CARBON COMPOSITE MATERIALS M. S. D a r i e l , S . Agam, D. E d e l s t e i n , 0. L e i b o v i t z and H. G l e i s e r

Var ious carbon and g r a p h i t e f i b e r r e i n f o r c e d carbon composites were p r e p a r e d by v a r y i n g t h e f i b e r , m a t r i x , f i b e r c o n f i g u r a t i o n and vo lume f r a c t i o n , f i b e r - m a t r i x i n t e r f a c e and p rocess ing pa rame te r s .

P o l y a c r y l o n i t r i l e (PAN) b a s e d f i b e r s of t e n s i l e s t r e n g t h be tween 320x10^ and 480x10^ p s i and t e n s i l e m o d u l i of, r e s p e c t i v e l y , 49x10° t o 33x10 p s i were used w i t h c o m b i n a t i o n s of epoxy and p h e n o l i c r e s i n c h a r s and c o a l and pe t ro leum based p i t c h e s . Composite m a t e r i a l s , h e a t - t r e a t e d t o

85

Fig. 3

Polished cross section of ^D C/C composite (X20)

Fig. 4 SEM photo of a rup tu red C/C composi te .

No p u l l out of f ibers (1) from matrix (2) observed (X5000)

2500°C, with bulk d e n s i t i e s >1.9 were ob ta ined . Sample s i z e s were up to 60 mm in diameter (Fip,. 3) .

Compressive s t rength at f a i lu re of up to 50,000 psi was measured for 3D c/c composite mater ia l . Crack i n i t i a t i o n was found to be mainly in the mat r ix reg ion (Fig 4 ) .

86

The i n f l u e n c e of p o r o s i t y and pore s i z e d i s t r i b u t i o n on f a i l u r e behavior and crack propagation, was invest igated based on data on density and h is tory of thermal treatment.

Additional mater ia ls invest igated were rayon-based graphite s a t in -weave c l o t h composites of p h e n o l i c r e s i n s in combination wi th coa l t a r p i tches t o obtain 2D composites of bulk density up to 1.8 with and without g r a p h i t i z a t i o n treatment.

THE COMPOSITE SYSTEM IRON-SILICON CARBIDE M. Ganor, Y. Gefen and J . Pel leg

This r e s e a r c h was performed in order to s tudy t h e p r o p e r t i e s of a me ta l l i c -ma t r ix composite in which an iron matrix was reinforced by SiC. The ceramic material was added in two forms, namely, p a r t i c l e s and chopped f i b e r s . The composite was manufactured by mixing meta l powders wi th the a p p r o p r i a t e amounts of a d d i t i v e s . Densification was accomplished by the hot i s o s t a t i c pressing (HIP) technique.

Some m e c h a n i c a l p r o p e r t i e s of t h e c o m p o s i t e m a t e r i a l were inves t iga ted . The influence of thermal treatment on the microstructure and mechanical proper t ies was evaluated.

Manufactur ing of the me ta l mat r ix composite Fe-SiC by means of powder metal lurgy techniques proved to give good r e s u l t s . The composite mater ia l reached i t s t heo re t i ca l density. Microstructures s imi la r to those observed in s t e e l s were developed by heat treatment.

Reaction between the iron matrix and the SiC add i t ives was detected a f t e r hea t t r ea tmen t a t e l e v a t e d t empera tu re s . The k i n e t i c s of the react ion was studied in order to gain control over the react ion zone width, thus making i t possible to get a more useful mater ia l .

LONG-TIME RESISTANCE OF JOINING OF ALUMINUM PLATES JOINED BY EPOXY RESIN E. Abramov, A. Raveh, B. Herrmann and E. Rabinovitz

Specimens of aluminum p l a t e ( type 2021) were sub jec ted to v a r i o u s surface treatments, and then joined by epoxy res in (type Scotchcast) [1 ] . The behavior of the j o i n t s with time was s t u d i e d and c h a r a c t e r i z e d . The j o i n t s were t e s t e d for shear s t r e n g t h c l o s e t o j o i n i n g t ime and a f t e r various s torage periods. The surfaces of the adhesion area of the f a i l ed aluminum p l a t e s were examined and c h a r a c t e r i z e d by o p t i c a l microscopy. Specimens examined a short time af ter the i r being joined showed a trend to cohesive f a i l u r e , while those stored for a longer period showed a trend to adhesive f a i l u r e . I t was found that the mean shear s t rength (MSS) behavior of the various surface treatments was different . This difference i s due to the weak adhesion between the anodic layer that is produced by chromic solut ion and epoxy r e s i n . REFERENCE: [1] Raveh, A., Herrmann, B. and Rabinovitz, E. in : IA-1412, 1985.


87

OPTICAL STUDY OF Ge^P-Te AND Ge-Se-Te CHALCOGENIDE GLASSES [ 1 ] L. Boehm, A. B o r n s t e i n and S. Ar ie

In t he p r e s e n t s tudy , t he major a t t r a c t i o n of cha l cogen ides l i e s in t h e i r promise as IR m a t e r i a l s for i n f r a r e d o p t i c a l f i b e r s . Such f i b e r s a r e needed in a p p l i c a t i o n s u s i n g high-power CO, l a s e r s for s u r g e r y , as w e l l a s in c u t t i n g and h e a t t r e a t m e n t of m e t a l s . These f i b e r s w i l l a l s o p l a y an impor tan t r o l e in the development of many i n f r a r e d d e v i c e s in the f i e l d of image r e l a y i n g and remote s e n s i n g .

We d e a l t wi th the p r e p a r a t i o n and o p t i c a l c h a r a c t e r i z a t i o n of two g l a s s systems c o n t a i n i n g r e l a t i v e l y h igh amounts of Te. Such g l a s s e s a re t r a n s p a r e n t up to 20 um and may s e r v e as preforms for drawing IR f i b e r s .

The s t a r t i n g m a t e r i a l s were semiconductor grade germanium, s e l en ium, and t e l l u r i u m of 99 .9999? p u r i t y , s u b j e c t e d t o a s p e c i a l p r o c e s s of p u r i f i c a t i o n by which ox ides a r e s e p a r a t e d by zone r e f i n i n g . The g l a s s e s were c u t and p o l i s h e d b e f o r e c o n d u c t i n g p h y s i c a l m e a s u r e m e n t s . X - r a y d i f f r a c t i o n showed t h a t a l l s a m p l e s were g l a s s y . S c a n n i n g e l e c t r o n m i c r o s c o p y showed h o m o g e n e i t y w i t h no p a r t i c l e s and p h a s e s e p a r a t i o n ( d e t e c t i o n l i m i t 3u ) in c o n t r a s t t o p r e v i o u s l y r e p o r t e d r e s u l t s for the Ge-Se-Te system.

I n t e r f e r o m e t r i c mapping of r e f r a c t i v e index inhomogeneity was used to d iagnose o p t i c a l i m p e r f e c t i o n s in components.

The IR s p e c t r a w e r e m e a s u r e d on p o l i s h e d s a m p l e s a t room t e m p e r a t u r e . F i g u r e 5 shows t h e IR s p e c t r a of 1.5mm t h i c k n e s s of t h e two

g l a s s e s , GepoS e5o' r e^O a n d G e23 5P3 0 T e 73 5 ' T h e S e b a s e d g l a s s i s seen t o be t r a n s p a r e n t up to 15 pm, w h i l e the g l a s s based on Ge-Te i s t r a n s p a r e n t up t o 20 Mm.

100

E 80

2 60 O

1 40 c a £ 20

0 2500 7500 12500 17500 22500

Wavelength (nm)

Fig . 5 E m i s s i o n s p e c t r a of Ge-P-Te g l a s s ( u n b r o k e n l i n e )

and Ge-Se-Te ( b r o k e n l i n e ) , 1.5 mm t h i c k n e s s

These g l a s s e s show a b s o r p t i o n up t o ^30 cm . G e20S e5OT e3O s " o w s a weak a b s o r p t i o n band a t 780 cm , due t o Ge-0 s t r e t c h i n g v i b r a t i o n . I t a r i s e s from an ox ide l a y e r or absorbed oxygen formed a t t h e s u r f a c e l a y e r of t h e Ge e l e m e n t u sed in t h i s p r e p a r a t i o n . The a b s o r p t i o n b a n d s a t 560 cm ' and 475 cm \ r e s p e c t i v e l y , , presumably r e s u l t from Ge-Se and Se~Se s t r e t c h i n g .

88

I t was concluded t h a t both g l a s s systems a r e p romis ing m a t e r i a l s fo r a p p l i c a t i o n in IR systems such a s f i b e r o p t i c s or IR components. REFERENCE: [ 1 ] Boehm, L., B o r n s t e i n , A. and A r i e , S., i n : NBS S p e c i a l P u b l i c a t i o n ,

697, 1985, p. 278.

STEP-INDEX CHALCOGENIDE GLASS FIBERS [ 1 ] A. B o r n s t e i n and L. Boehm

O p t i c a l f i b e r s of a r s e n i c s e l e n i d e core and c l a d d i n g were f a b r i c a t e d and coated wi th t e f l o n for p r o t e c t i o n . The s t e p index f i b e r was ob ta ined by c o n t r o l l i n g th-= molar p e r c e n t a g e s of As and Se. The f i b e r s were drawn by the rod method i n s i d e an Ar atmosphere g l o v e box. Th i s p rocess pe r mi t s producing a f i b e r wi th t he numer ica l a p e r t u r e r e q u i r e d for v a r i o u s medical a p p l i c a t i o n s . REFERENCE: [ 1 ] Borns t e in , A. and Boehm, L., i n : Proceed ings of the 6 th Congress of the

I n t e r n a t i o n a l Soc. for Laser Surgery and Medicine, J e rusa l em, October 1985, p. H.

CHALCOGENIDE HOLLOW FIBERS [1 ]

A. B o r n s t e i n and N. Croifcoru Chalcogenide g l a s s ho l low f i b e r s were f a b r i c a t e d by drawing from an

As-Se or As-Ge-Sb cha l cogen ide g l a s s c y l i n d e r . Very p r e c i s e c o n t r o l was mainta ined dur ing drawing t o o b t a i n uniform h o l l o w f i b e r s . The tube was produced from oxygen-free raw m a t e r i a l s i n s i d e an argon atmosphere g l o v e box. The o u t s i d e d iamete r s of the f i b e r s were 300 t o 500 um and the i n s i d e d i a m e t e r s 100 t o 300 ym. The f i b e r s were s m a l l , l i g h t , and f l e x i b l e and could t r a n s m i t C0~ l a s e r l i g h t as w e l l as v i s i b l e l i g h t . The a t t e n u a t i o n of the d i e l e c t r i c h o l l o w f i b e r s remained c o n s t a n t even when bent t o s m a l l r a d i i of 2 cm. The f i b e r s have an a t t e n u a t i o n of 0.5 dB/cm. REFERENCE:

[ 1 ] B o r n s t e i n , A. and C r o i t o r u , N., J . N o n - C r y s t . S o l i d s 11_ & J 8 , 1277

(1985) .

THERMAL ANALYSIS OF B0R0SILICATE GLASS [ 1 ] A. N. Sembira

D i f f e r e n t i a l t h e r m a l a n a l y s i s (DTA) and thermomechanical a n a l y s i s (TMA) of b o r o s i l i c a t e g l a s s e s permit the d e t e r m i n a t i o n of the t empera tu re a t which g l a s s t r a n s f o r m a t i o n occurs . An equat ion d e r i v e d by R i t l a n d and extended by Moynihan r e l a t i n g the coo l ing r a t e and f i c t l v e t empera tu re was used t o c a l c u l a t e t h e a c t i v a t i o n e n t h a l p y . The l i m i t i n g f i c t i v e t e m p e r a t u r e ( T f ) , o b t a i n e d d u r i n g a g l a s s c o o l i n g p r o c e s s t h r o u g h t h e

Tel-Aviv U n i v e r s i t y , Ramat'-Aviv

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transition region, was shown to be related to the cooling rate, q, by:

d(lnq)/d(l/Tf) = -Ah*/R

where R i s the i d e a l gas c o n s t a n t and Ah i s the a c t i v a t i o n e n t h a l p y for the re laxat ion times cont ro l l ing the s t r u c t u r a l r e l axa t ion . REFERENCE: L1] Sembira, A. N., i n : P roceed ings of the 51s t meeting of the I s r a e l

Chemical Society, Oct. 1985, p. 55.

PRESSURE EFFECTS IN MOLTEN SALT GALVANIC CELLS B. Vainas and M. Gur

Expansion of the e lec t rode mater ia l s of a c e l l confined between two fixed current c o l l e c t o r s can cause short c i r cu i t i ng between the anode and the cathode, while contraction of these mater ia l s can cause an increase in the in t e rna l r es i s t ance due to the reduction of the a x i a l pressure ensuring the physical contact between the current c o l l e c t o r s and the e lec t rodes . We studied the volume changes of the galvanic c e l l elements by measuring the a x i a l pressure va r i a t ions created by a c e l l confined between two current co l l ec to r s at a fixed dis tance apar t .

During the discharge of the LiAl/KCl, LiCl/FeS2 molten s a l t c e l l s , the ax ia l pressure on the fixed current c o l l e c t o r s increases. C e l l s kept under open c i r c u i t c o n d i t i o n s show a very slow dec rease in p r e s s u r e , probably due to the re laxa t ion of the i n i t i a l l y appl ied a x i a l pressure by slow p l a s t i c deformation of the e lec t rode mater ia l s .

The pressure increase during discharge c o r r e l a t e s with the p a r t i c l e s i ze of the FeS~ mate r ia l ; a larger pressure increase occurs when larger p y r i t e p a r t i c l e s are used. We e x p l a i n t h i s r e s u l t as due to reduced e n c a p s u l a t i o n of the l a r g e r p y r i t e p a r t i c l e s by the molten e l e c t r o l y t e contained in the cathode p e l l e t .

As the r e s u l t of the e l e c t r o c h e m i c a l r e d u c t i o n of p y r i t e dur ing discharge, a new so l id phase i s formed on the pyr i t e p a r t i c l e s [1 ] , This phase i s l e s s dense than the p y r i t e i t s e l f , and t h e r e f o r e the o r i g i n a l p a r t i c l e s increase in s ize . We be l i eve that the close-packed large pyr i te p a r t i c l e s produce pronounced mechanical p r e s s u r e on the f ixed c u r r e n t c o l l e c t o r s upon discharge. REFERENCE: [ 1 ] Q u i n n , R.K., B a l d w i n , A.R., Armi jo , J .R., N e i s w a n d e r , P.G. and

Zurawaski, D, E., Development of a Lithium A l l o y / I r o n D e s u l f i d e , 60-minute Primary Thermal Battery, Sandia Report, SAN 7908H), 1979.

THE MORPHOLOGY OF YTTRIUM-ALUMINUM-GARNET CRYSTALS

S. Biderman, Y. Shimony, Z. Burshtein and U. Laor

Pure and Nd^+ doped y t t r i um-a luminum-ga rne t (YAG) and Ho3++TnH+-doped yttrium-erbium-aluminum-garnet c r y s t a l s were grown by the Czochralski method in the <111> c r y s t a l l o g r a p h i c d i r e c t i o n . Crystal morphology was

90

s t u d i e d by means of X- ray d i f f r a c t o m e t r y i n o r d e r t o i d e n t i f y t h e c r y s t a l l i n e f a c e t s . C o r r e l a t i o n was found between f a c e t s and t h e l o c a t i o n of s t r a i n e d zones in t h e c r y s t a l s .

L a s e r r o d s f a b r i c a t e d from t h e a b o v e c r y s t a l s were s u b j e c t e d t o e x t i n c t i o n - r a t i o (ER) m e a s u r e m e n t , which i n d i c a t e s o p t i c a l q u a l i t y . Thermal t r e a t m e n t was found to be very e f f e c t i v e in r e d u c i n g t h e induced s t r e s s in t h e l a s e r r o d s ; h e a t i n g a t 1000°C f o r 24 h i n an u n c o n t r o l l e d a t m o s p h e r e y i e l d e d an a v e r a g e i n c r e a s e i n t h e ER o f 10 dB, which i s a s i g n i f i c a n t improvement in t he rod q u a l i t y .

GROWTH OF CHALCOPYRITE CRYSTALS: ZnGeP2 AND ZnSiPg Y. Shimony and A. Wold

Th i s s tudy was p a r t of a r e s e a r c h program aimed a t d e v e l o p i n g new s y n t h e t i c t e c h n i q u e s f o r t h e o p t i m i z a t i o n of f a r i n f r a - r e d t r a n s m i t t i n g o p t i c a l components wi th s u f f i c i e n t l y good mechan ica l , t he rma l and o p t i c a l p r o p e r t i e s . Ternary phosphides , such as ZnSiP2 , ZnGeP2, MgSiP2 and MgGeP2>

a r e e x p e c t e d t o be t r a n s p a r e n t i n t h e 8-12 um r e g i o n , a s w e l l a s t o h a v e a p p r e c i a b l e m e c h a n i c a l s t r e n g t h and h a r d n e s s , t o w i t h s t a n d t h e o p t i c a l r e q u i r e m e n t s and ha r sh env i ronmen ta l c o n d i t i o n s needed for dome m a t e r i a l s .

P r e p a r a t i o n of ZnGeP2 and ZnSiP2 was a t t empted by d i r e c t combinat ion of t h e e l e m e n t s and by s i n g l e c r y s t a l g rowth . I n b o t h m e t h o d s s e a l e d e v a c u a t e d s i l i c a t u b e s were used b e c a u s e of t h e t e n d e n c y o f ZnGePp and Z n S i P 2 t o t h e r m a l d e c o m p o s i t i o n and of t h e l a r g e a f f i n i t y of t h e c o n s t i t u e n t s for oxygen. The p o l y c r y s t a l l i n e m a t e r i a l s were p repa red u s i n g a very s low h e a t i n g r a t e to avo id e x p l o s i o n of t h e r e a c t i o n v e s s e l . Two c r y s t a l g r o w t h t e c h n i q u e s were employed in t h e c o u r s e of t h i s s t u d y . C h e m i c a l v a p o r t r a n s p o r t (CVT) was used t o grow b o t h c r y s t a l s u s i n g c h l o r i n e a s t h e t r a n s p o r t agent . This method y i e l d e d very s m a l l (2-4 mm) c r y s t a l s wi th w e l l def ined f a c e t s . ZnGeP2 c r y s t a l s were a l s o grown from the me l t by t h e Bridgman techn ique and by d i r e c t i o n a l f r e e z i n g in g r a p h i t e and s i l i c a tubes .

The o p t i c a l t r a n s m i s s i o n s p e c t r a of t h e s i n g l e c r y s t a l s were measured i n o rde r to determine the t r a n s p a r e n c y r eg ion and t h e a b s o r p t i o n edge . Z n S i P 2 was found t o be t r a n s p a r e n t be tween 0 . 8 8 - 1 3 urn w i t h an abso rp t ion edge of 1.71 eV, w h i l e ZnGeP2 was found t o be t r a n s p a r e n t i n t he range of 0 .75-12 um wi th an a b s o r p t i o n edge of 2,21 eV.

OPTICAL GERMANIUM CRYSTAL GROWTH AND CHARACTERIZATION M. Azoulay, G. Gafni and M. Roth

Germanium i s w i d e l y u sed a s an o p t i c a l m a t e r i a l i n t h e i n f r a r e d . C r y s t a l s of h i g h o p t i c a l q u a l i t y a r e t h e r e f o r e n e e d e d , e s p e c i a l l y w i t h

This work was performed a t Brown U n i v e r s i t y , P rov idence , RI, U.S.A. Brown U n i v e r s i t y , P rov idence , RI, U.S.A. Hebrew U n i v e r s i t y , J e rusa l em

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respect to the homogeneity of the r e f r ac t i ve index and minimum absorption in the r eg ion of i n t e r e s t , namely 8-12 ym [ 1 ] . Doping of h igh p u r i t y germanium with n _ type i m p u r i t i e s , e.g. Sb, P or As, i s used to o b t a i n the low o p t i c a l ab so rp t i on r e q u i r e d . The minimum abso rp t ion c o e f f i c i e n t corresponds to a c o n c e n t r a t i o n of about 10 at/cm^ [ 2 ] , The problem of uniform, d i s t r ibu t ion of the dopant becomes, however, c r i t i c a l when large s ingle c r y s t a l s are grown.

In the present work, s ing le c r y s t a l s were grown by the Czochralski method (Figs . 6,7). I t was shown t h a t even in the case of very l a r g e c r y s t a l s (up to 200 mm diameter) un i fo rmi ty of the r a d i a l dopant d i s t r i b u t i o n can be ach ieved , provided t h a t the r a d i a l t empera tu re g r a d i e n t s in the mel t a re minimized. The a x i a l dopant s e g r e g a t i o n was found t o obey t h e normal f r e e z i n g b e h a v i o r , whi le the e f f e c t i v e d i s t r ibu t ion coeff icient was ca lcu la ted according to BPS theory [3 ] . Good agreement between theory and expe r imen ta l r e s u l t s was demonstra ted. C o n t r o l l e d p r e s s u r e above the mel t should be mainta ined in the case of v o l a t i l e dopants, in order to prevent losses by evaporation. The minimum pressure of the blanket gas was ca lcula ted .

Fig. 6 "Hamco" automatic diameter control pul ler

The d i rec t determination of antimony concentration was performed by neut ron a c t i v a t i o n a n a l y s i s and the r e s u l t s were compared with the f ree car r ie r concentrations derived from the Hal l effect and four point probe measurements. The e l e c t r i c a l a c t i v i t y of antimony in Czochralski pu l led c r y s t a l s and l a r g e g r a i n c a s t i n g s was compared and the d i f f e r e n c e s were explained in terms of the dopant p rec ip i t a t ion a t grain boundaries.

The c r y s t a l p e r f e c t i o n was assessed by chemical e t c h i n g , us ing a s e l e c t i v e e t c h a n t for the (111) c r y s t a l l o g r a p h i c p l a n e . The e tch p i t density var ies concen t r ica l ly from about 10 cm ^ at the c r y s t a l edge to

92

F i g . 7 Germanium s i n g l e c r y s t a l s grown in t he p u l l e r in F i g . 6

10-* cm a t i t s c e n t e r . A s i m i l a r c o n c e n t r i c v a r i a t i o n of the r e f r a c t i v e index was observed . The q u a n t i t a t i v e c o r r e l a t i o n between e t c h p i t d e n s i t y and r e f r a c t i v e index was c o n s i d e r e d in terms of d i s l o c a t i o n induced e l a s t i c s t r a i n s . REFERENCES: [1] Donald, I . W. and McMillan, P . W., J . Mater . S o i . V3, 1151 (1978) . [ 2 ] Capron, E. D. and B r i l l , 0. L . , Appl. Opt. V2, 569 (1973) . [3 ] B u r t o n , J . A., P r im, C. and S l i c h t e r , W. P . , J . Chem. P h y s . 2±, 1987

(1953) .

SEEDED GROWTH IN A SOFT LINED CRUCIBLE: APPLICATION TO PHOSPHORUS DOPED OPTICAL GERMANIUM SINGLE CRYSTALS

M. Azoulay, G. Gafni and M. Roth The p e r f e c t i o n of s i n g l e c r y s t a l s grown from t h e m e l t by t h e

Br idgman-Stockbarger Method, Heat Exchange Method and r e l a t e d t e c h n i q u e s i s known to be degraded due t o mechanica l s t r e s s e s a r i s i n g from the d i f f e r e n c e in the the rmal expansion c o e f f i c i e n t s of the s o l i d i f y i n g c r y s t a l and the c o n t a i n e r w a l l s . A p a r t i c u l a r p r o b l e m o c c u r s w i t h germanium and o t h e r m a t e r i a l s t h a t h a v e a g r e a t e r t h a n u n i t y l i q u i d - t o - s o l i d d e n s i t y r a t i o . The idea of employing a " f l e x i b l e " c r u c i b l e was t h e r e f o r e sugges t ed in the p r e s e n t work.

Germanium s i n g l e c r y s t a l s of up to 100 mm diameter were grown on a b o t t o m mounted s e e d u s i n g a m o d i f i e d Heat Exchange Method. G r a p h i t e c r u c i b l e s l i n e d wi th a so f t g r a p h i t e f e l t were employed. The f e l t s h r i n k s e a s i l y a l l o w i n g t h e s o l i d i f y i n g c r y s t a l t o e x p a n d , and t h e m e c h a n i c a l s t r e s s e s d e v e l o p i n g in the c r y s t a l a re t h u s reduced s i g n i f i c a n t l y . S p e c i a l

Hebrew U n i v e r s i t y , J e rusa l em

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ca re was taken to reduce the r a d i a l g r a d i e n t i n o rder t o approach a p l a n a r i n t e r f a c e .

S i n c e s l i g h t l y n _ t ype Ge i s u s u a l l y employed in i n f r a r e d o p t i c s , t he m a t e r i a l was doped w i t h p h o s p h o r u s t o c o n c e n t r a t i o n s of a b o u t 101 cm~3. The s m a l l c o n c e n t r a t i o n of t h e dopan t d o e s n o t a l t e r t h e c r y s t a l l i n e q u a l i t y of t h e m a t e r i a l , and c r y s t a l s w i t h low e t c h p i t d e n s i t i e s (< 10^ cm~^) h a v e been r o u t i n e l y o b t a i n e d . The e t c h p i t d e n s i t i e s of t h e c r y s t a l s were a lways s m a l l e r t han those of t he seeds . The r a d i a l and a x i a l d i s t r i b u t i o n s of p h o s p h o r u s w e r e o b t a i n e d f rom t h e r e s i s t i v i t y measurements.

The o p t i c a l homogeneity of the c r y s t a l s in the i n f r a r e d was s t u d i e d . Numerical a n a l y s i s of t he i n t e r f e r e n c e p a t t e r n s showed t h a t t h e v a r i a t i o n of t h e r e f r a c t i o n i n d e x (An) i s t y p i c a l l y a s low a s 1 0 ~ - \ The e x c e l l e n t o p t i c a l q u a l i t y of the c r y s t a l s i s a l s o confirmed by measurements of the m o d u l a t i o n t r a n s f e r f u n c t i o n c u r v e s h o w i n g a r e d u c t i o n of o n l y 2% i n comparison wi th t he d i f f r a c t i o n l i m i t e d c u r v e .

The p o s s i b i l i t y of g r o w i n g o t h e r h i g h o p t i c a l q u a l i t y m a t e r i a l s u s i n g t h e " f l e x i b l e " c r u c i b l e method i s s u g g e s t e d . T h i s method d o e s n o t r e q u i r e t he s o p h i s t i c a t e d equipment used in t h e modern C z o c h r a l s k i p u l l e r s , and may be of advantage in some cases .

MERCURY ZINC TELLURIDE EPILAYERS GROWN BY LPE [ 1 ] A. Sher , D. Eger , A. Zemel, H. F e l d s t e i n and A. Raizman

E p i l a y e r s o f Hgg g i )Zn 0 ^ T e w e r e g rown by LPE on CdTe and CdQ 76Zn0 2 i4 T e s u b s t r a t e s . The grown s t r u c t u r e s were s t u d i e d by X-ray Laue back r e f l e c t i o n , d i f f r a c t i o n r o c k i n g c u r v e s , s u r f a c e morphology, c r o s s -s e c t i o n a l v iew and i n f r a r e d t r a n s m i s s i o n s p e c t r a . E p i l a y e r s w i t h h i g h c r y s t a l l i n e p e r f e c t i o n , smooth m o r p h o l o g y , f r e e of r e s i d u a l m e l t and i n c l u s i o n s , s h a r p i n t e r f a c e w i t h o u t i n t r u s i o n s and s h a r p i n f r a r e d a b s o r p t i o n edge were o b t a i n e d when grown on t h e n e a r l y l a t t i c e matched CdQ 75ZnQ 2H T e s u b s t r a t e s . REFERENCE :*

[13 S h e r , A . ,Eger , D., Z e m e l , A., F e l d s t e i n , H. and Raizman, A., J . C r y s t . Growth 7 2 , 108 (1985)

DIRECTIONAL GROWTH OF CdTe CRYSTALS

H. F e l d s t e i n , A. Raizman and R. Aharonovi tz Cadmium t e l l u r i d e c r y s t a l s for e l e c t r o o p t i c a l d e v i c e s were grown by

t h e Br idgman method [ 1 ] . A s e a l e d q u a r t z ampou le w i t h m o l t e n CdTe was p u l l e d a t a c o n s t a n t r a t e of 1-2 mm/h t h r o u g h a t e m p e r a t u r e g r a d i e n t of 10-20°C/cm. A d o u b l e c r y s t a l d i f f r a c t o m e t e r (DCD) i n t h e n o n d i s p e r s i v e s e t t i n g was used t o e v a l u a t e t h e c r y s t a l l i n e q u a l i t y . For t h e f i r s t c r y s t a l we used a (111) o r i e n t e d , n e a r l y p e r f e c t , InSb c r y s t a l , a d j u s t e d t o t h e (333) r e f l e c t i o n . Rocking curves of CdTe c r y s t a l s on t he (333) p l a n e were t aken . The a n g u l a r b r e a d t h of the d i f f r a c t i o n c u r v e i s i n d i c a t i v e of t h e q u a l i t y of the c r y s t a l .

91

I t was found t h a t most CdTe c r y s t a l s examined were r a d i a l l y unisotropic and the breadth of the rocking curves changed with the ro t a t ion of the c r y s t a l around an a x i s p e r p e n d i c u l a r t o the r e f l e c t i n g p l a n e . A c o r r e l a t i o n was found between the b read th of the rock ing curve and the d i r e c t i o n of growth of the c r y s t a l . A CdTe (111) p l a n e was cu t making an a n g l e of -27° wi th the growth d i r e c t i o n . The p l a n e was scanned by a 0.4x5 mm X-ray beam. When t h e beam was p e r p e n d i c u l a r to the growth a x i s , a l l the diffracted peaks were s ing le and narrow with an average width of 0.008° a t ha l f maximum. By ro t a t i ng the c r y s t a l 90° (now the scanning beam was almost p a r a l l e l to the growth axis) the rocking curve was s p l i t into numerous peaks (up to 9) i n d i c a t i n g a very g ra iny m a t e r i a l (F ig . 8). Repeated measurements of a (111) p l ane making an a n g l e of 74° wi th the growth axis gave s imi la r r e s u l t s , but with much narrower s p l i t t i n g .

Fig. 8 Rocking curves of CdTe, (111) plane

a) X-ray beam p a r a l l e l to growth front; b) X-ray beam perpendicular to growth front . S l i t dimensions: 0.4x5 mm,' s ca l e : 0.022°/cm

The above r e s u l t s i n d i c a t e t h a t t he c r y s t a l grows in l a y e r s p e r p e n d i c u l a r to the growth a x i s . The l a y e r s a re of high c r y s t a l l i n e qua l i ty and separated by low angle grain boundaries. These "growth steps" uay r e s u l t from interrupted growth caused by inadequate adjustment between the temperature gradient at the s o l i d - l i q u i d in terface and the ve loc i t y of p u l l i n g of t h e ampoule. B e t t e r adjustment of t h e s e pa ramete r s w i l l possibly r e s u l t in large i so t rop ic grains with narrow di f f rac t ion peaks. REFERENCE: [1] Yell in, N., p r iva te communication, 1984.

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PLASMA PROCESSES IN PACVD OF SUN,, AND SiC COATINGS A. Inspektor, U, Carmi and R. Avni

Plasma ac t iva ted chemical vapor deposition (PACVD) and propert ies of a desired so l id film are determined by processes in the plasma-bulk and in the ac t iva t ion luminous zone at the plasma-surface boundary. In the plasma bulk t h e s e r e a c t i o n s a re homogeneous, whereas a t the p la sma-su r face boundary the react ions are heterogeneous. This work was aimed at analyzing the effects of various s i l i con , nitrogen and carbon reactant sources and of the main experimental var iab le parameters on the deposition processes and on the p r o p e r t i e s of Si^N^ and SiC f i l m s . This r e s e a r c h inc luded c h a r a c t e r i z a t i o n of the a p p r o p r i a t e plasma mix tures , study of the d e p o s i t i o n r a t e and c h a r a c t e r i z a t i o n of the l a y e r produced. The main primary and secondary p roces se s in the formation of Si^N^ and SiC f i lms were compared with those reported by other workers. Special emphasis was g iven to the e f f e c t of the va r ious r e a c t a n t s , ( i . e . SiCljj or SiH^, NH, or N2, CXH or TMS ( t e t r a - m e t h y l - s i l a n e ) ) and to the e f f e c t of admixing hydrogen.

I t was found tha t the main effect of hydrogen is to enhance the free r a d i c a l c o n c e n t r a t i o n in the plasma and thus to promote the r a d i c a l mechanism. This addit ion (of hydrogen) i s accordingly accompanied by the reduction of the mean e lec t ron energy and the pos i t ive ion density. An ion molecu le mechanism i s a f f ec t ed by the e l e c t r i c p o t e n t i a l , such t h a t the grounded or n e g a t i v e l y b iased s u b s t r a t e i n c r e a s e s the d e p o s i t i o n r a t e , w h e r e a s a r a d i c a l mechanism i s promoted on a f l o a t i n g s u b s t r a t e . Generally, bet ter proper t ies of the Si^N^ fi lms were obtained on a f loa t ing s u b s t r a t e , i n d i c a t i n g t h a t the formation of the f i lm i s p r e f e r r e a by the radical-molecule mechanism. The admixing of hydrogen with the TMS inh ib i t s the d i s s o c i a t i o n of the TMS and reduces the Si/C r a t i o in the SiC f i lm as determined by ESCA ana lys i s .

OXIDATION REACTION OF PYROLYTIC CARBON COATING [1] A. Raveh, A. Inspektor, U. Carmi, E. Rabinovitz and R. Avni

The behavior of p y r o l y t i c carbon c o a t i n g s on commercial grade g r a p h i t e s u b s t r a t e in ox id i z ing environment was studied. Specimens were examined under sput ter ing in plasma of oxygen and argon, or in an oxidizing so lu t ion of K2Cr20y + H^PO . Specimens of commercial grade graphite (ATJ) were quickly eroded under these conditions, compared with coated specimens. The e ros ion r a t e of the coa t ing i s dependent on i t s t h i c k n e s s and on the mean mont icu le d iameter . The coa t i ngs d i s i n t e g r a t e d in the o x i d i z i n g environment in three s teps : etching of monticule boundaries; widening of the boundaries or cracking of the coating; f a l l i n g off of the coating. The degree of e ros ion decreased with i n c r e a s i n g mean mont icu le diameter and inc reased where the diameter was non-homogeneous. The res i s tance of the c o a t i n g to wear, under these ox id i z ing c o n d i t i o n s , can be enhanced by

96

homogenizat ion of the c o a t i n g and by i t s d e p o s i t i o n in l a y e r e d f i l m s . REFERENCE:

[ 1 ] R a v e h , A., I n s p e k t o r , A., Carmi , U., R a b i n o v i t z , E. and A v n i , R., NRCN-

510, 1985, in Hebrew.

SILICON CARBIDE COATING ON STAINLESS STEEL SUBSTRATE BY THE COLD PLASMA TECHNIQUE

A. I n s p e k t o r , A. Raveh, Y. Wietzman, U. Carmi and R. Avni

Ceramic c o a t i n g s such as SiC, Si^N^, TiB- and TiC h a v e good e r o s i o n and h o t - c o r r o s i o n r e s i s t a n c e . M a r t e n s i t i c s t a i n l e s s s t e e l (AISI-H10) was coa ted wi th SiC f i l m s u s i n g the co ld plasma t echn ique . The s u b s t r a t e t empe ra tu r e was lower t han 500°C. This t empera tu re p r e v e n t s development of h i g h s t r e s s and m a i n t a i n s t h e h e a t t r e a t m e n t c o n d i t i o n s . The f i l m s were produced by a plasma of t e t r a - m e t h y l - s i l a n e (TMS) and hydrogen in argon. The d e p e n d e n c e of d e p o s i t i o n r a t e and t h e m i c r o - h a r d n e s s o f t h e f i l m s on t h e h y d r o g e n c o n c e n t r a t i o n i n t h e feed and t h e t o t a l g a s p r e s s u r e i n t h e r e a c t o r were s tud i ed .

The f i l m s were c h a r a c t e r i z e d by means of X-ray d i f f r a c t i o n , o p t i c a l microscopy, scanning e l e c t r o n microscopy, Auger e l e c t r o n s p e c t r o s c o p y (AES) and V i c k e r s microhardness . I t was found t h a t the maximum d e p o s i t i o n r a t e was 18 um/h, and t h e maximum m i c r o h a r d n e s s was 3100 kgf/mm . X- ray examina t ions showed t h a t the d i f f e r e n t c r y s t a l l o g r a p h i c s t r u c t u r e s of t h e c o a t i n g s p r o d u c e d a r e d e p e n d e n t on t h e p l a s m a w o r k i n g p a r a m e t e r s . The c o a t i n g s t r u c t u r e s v a r i e d from amorphous SiC t o SiC wi th a h igh degree of ( h e x a g o n a l a - S i C ( IV) ) c r y s t a l U n i t y h a v i n g a u n i t c e l l a Q = 3.073 A and c

0 = 52 - 78 A. The h y d r o g e n c o n c e n t r a t i o n i n t h e feed was found t o p l a y an impor tan t r o l e in the s t r u c t u r e , composi t ion (AES measurements) and the d e n s i t y of the f i lms .

DEPOSITION OF PYROCARBON IN LOW TEMPERATURE ENVIRONMENT

A. I n s p e k t o r , U. Carmi, A. Raveh, Y. Khait and R. Avni

In t h i s work pyrocarbon (PyC) c o a t i n g s were p repa red a t r e l a t i v e l y low t e m p e r a t u r e s (300-500°C) and t h e i r p r o p e r t i e s s t u d i e d . The d e p o s i t i o n p r o c e s s which i s performed in a n o n - e q u i l i b r i u m low p r e s s u r e r f plasma of p r o p y l e n e - a r g o n m i x t u r e s p e r m i t s t h e c o a t i n g of t h e r m a l l y s e n s i t i v e m a t e r i a l s . The format ion of the c o a t i n g i s e x p l a i n e d by ( t he p l a s m a - w a l l coup l i ng ) p r o c e s s e s o c c u r r i n g in t he p l a s m a - s u r f a c e boundary r eg ion . The p r o p e r t i e s of t h e c o a t i n g s were found t o be s i m i l a r t o t h o s e of CVD-PyC f i l m s o b t a i n e d a t h i g h e r t e m p e r a t u r e s (>1000°C). The measured p r o p e r t i e s were c o r r e l a t e d wi th the e x p e r i m e n t a l working pa ramete r s for t he d e p o s i t i o n of pyrocarbon.


97

PLASMA ACTIVATION OF CARBON CLOTH

A. I n s p e k t o r , J . E. Koresh, S . S . Bar ton and M. J . B. Evans A porous carbon c l o t h was t r e a t e d wi th a hydrogen p lasma before and

a f t e r a i i a c t i v a t i o n . Changes in t he pore s t r u c t u r e were f o l l o w e d by water vapor a d s o r p t i o n and e n t h a l p y of immersion measurements. The a c t i o n of a c a r b o n d i o x i d e p l a s m a i s s i m i l a r i n n a t u r e , b u t g r o s s c h a n g e s i n f i b e r m o r p h o l o g y a r e o b s e r v e d . I t was c o n c l u d e d t h a t t h e p l a s m a t r e a t m e n t a f f e c t s o n l y t h e e a s i l y a v a i l a b l e p a r t of t h e p o r o u s c a r b o n and t h a t r e a c t i o n w i t h i n the s m a l l e r pores does not t ake p l a c e u n t i l t h e r e has been a g r e a t d e a l of su r f ace d e g r a d a t i o n . I t f o l l o w s from t h i s t h a t t h e su r f ace oxides w i t h i n the micropore system a re not reduced by the hydrogen plasma and t h i s method of r e d u c t i o n may be of v a l u e i n d i f f e r e n t i a t i n g be tween m i c r o p o r e f i l l i n g and a d s o r p t i o n on h y d r o p h i l i c s i t e s on more open s u r f a c e s .

SUBSTRATE PREPARATION BY CONTACTLESS MECHANOCHEMICAL POLISH [ 1 ]

S . R o t t e r , U. Lachish and U. El-Hanany A s i m p l e , y e t e f f e c t i v e , p o l i s h i n g t e c h n i q u e f o r s u b s t r a t e

p r e p a r a t i o n was deve loped . I t i s a c o n t a c t l e s s chemical p o l i s h which does n o t i n t r o d u c e any d e f e c t s i n t o t h e s u b s t r a t e d u r i n g t h e p r o c e s s . The method can be r e a d i l y a d a p t e d i n a l l c a s e s where c h e m i c a l p o l i s h i n g i s p r a c t i c a l for s u b s t r a t e p r e p a r a t i o n . R e s u l t s s i m i l a r t o t h o s e ob ta ined by the more s o p h i s t i c a t e d hydrop lan ing method can be ach ieved . REFERENCE:

[ 1 ] R o t t e r , S. , L a c h i s h , U. and E l - H a n a n y , U., J . C r y s . Growth T_l 1 8 ? »

(1985) .

LATTICE MISMATCH AND THE NATURE OF DISSOLUTION IN THE LPE OF Pb-SALT COMPOUNDS [ 1 ]

S . R o t t e r

L a t t i c e m a t c h i n g was shown e x p e r i m e n t a l l y t o be i m p o r t a n t i n d e t e r m i n i n g t h e n a t u r e of t h e s o l i d / s o l u t i o n i n t e r f a c e b e h a v i o r d u r i n g c o n t r o l l e d m e l t b a c k n e a r s a t u r a t i o n c o n d i t i o n s . We d e f i n e t h e l a t t i c e matching between a c r y s t a l l i n e s u b s t r a t e and a s o l u t i o n v i a the s o l i d in e q u i l i b r i u m w i t h t h e s o l u t i o n and , i n a s i m i l a r way, l a t t i c e mismatch c o n d i t i o n s can be d e f i n e d a s w e l l . We found t h a t a f l a t i n t e r f a c e i s p r e s e r v e d dur ing mel tback and rcgrowth i f the s o l u t i o n i s l a t t i c e matched t o t h e s u b s t r a t e e v e n when t h e y a r e of d i f f e r e n t c h e m i c a l p o t e n t i a l s . M e l t b a c k and r e g r o w t h under matched c o n d i t i o n s h a s been u sed t o form g r a d e d - g a p h e t e r o s t r u c t u r e s w i t h f l a t i n t e r f a c e s . We s u g g e s t u s i n g u n d e r s a t u r a t e d l a t t i c e matched s o l u t i o n s whenever an i n s i t u removal of the top p a r t of a s u b s t r a t e i s needed p r i o r t o e p i t a x i a l growth. REFERENCE: [1 ] R o t t e r , S.,, J . E l e c t r o n . Ma te r . , in p r e s s .

Royal M i l i t a r y Col lege of Canada, Kingston, O n t a r i o , Canada

98

SINTERING PROCESS CHARACTERIZATION BY SOUND WAVE VELOCITY MEASUREMENTS [1]

H. Klimker and Y. Gefen

Physical and metallurgical effects in solids can be characterized by

the variation of the sound wave velocity. The purpose of this research was

to characterize by ultrasonics measurements the cold compaction and

sintering of iron powder. The sound wave velocity was determined as a

function of porosity (Fig. 9), cold compaction pressure, temperature and

sintering time.

^ 6 o a tn "^ e

°o . o <o

1 4 a c •D _2 '5> § 3

2 5 10 15 20 25 30

Porosity (%)

Fig. 9 Longitudinal sound wave ve loc i ty as a function of porosi ty

G - green powder compacts, S - powder compacts s intered at 1000°C for 2 h

I t was found t h a t four parameters a re impor tant in the sound wave dependence. On one hand, an i n c r e a s e in the dens i ty and i n t e r p a r t i c l e bonds causes a r i s e in the sound wave ve loc i ty , while on the ether hand the p l a s t i c deformation of the p a r t i c l e s during cold compaction and the spring back e f f e c t c o n t r i b u t e to a decrease in the sound wave v e l o c i t y . During cold compaction in the low pressure range, f i r s t there is a l i nea r increase in the sound wave v e l o c i t y as the p r e s s u r e i s r a i s e d . As the compaction pressure is ra ised above 0.5 GPa (5000 bar) the sound wave ve loc i ty becomes pressure independent, while the density continues to increase. After the s in t e r ing process, such behavior is not found as the heat treatment ac t s to anneal out the p l a s t i c deformation and d i s loca t ions .

The behavior of the sound wave ve loc i ty var ia t ion as a function of temperature and time of the s in te r ing process character izes the beginning and the end of the consol idat ion process.

\ ^ ^ \ \ ^ " ^

_ \ \

\ \

\

I I

-.s

\G

I I I \ i

99

As c o n c l u s i o n , t h e s e m e a s u r e m e n t s show t h a t , i n a d d i t i o n t o t h e c o n v e n t i o n a l method, t h e r e i s an easy NDT way t o c h a r a c t e r i z e the s i n t e r i n g p r o c e s s . REFERENCE:

[1 ] K l i m k e r , H. and Gefen, Y., T h i r d I s r a e l M a t e r i a l s E n g i n e e r i n g Conference, Haifa , December 1985, A b s t r a c t 7 . 3 - 3 , in Hebrew.

STUDY OF CHEMICAL STRUCTURE OF FILMS FORMED ON A COMMERCIAL 18*-Cr FERRITIC STAINLESS STEEL M. Ben-Haim, N. Shamir, U. Atzmony and J . Yahalom

A u s t e n i t i c s t a i n l e s s s t e e l s can be c a t h o d i c a l l y p r o t e c t e d by h i g h l y concen t r a t ed n i t r i c ac id s o l u t i o n s . P r e l i m i n a r y exper iments i n d i c a t e d t h a t such a type of e l e c t r o c h e m i c a l p r o t e c t i o n may a l s o be f e a s i b l e fo r low cos t f e r r i t i c s t a i n l e s s s t e e l s . In t h i s t ype of p r o t e c t i o n , t h e s t a i n l e s s s t e e l i s s h i f t e d from the f r e e l y co r rod ing p o t e n t i a l in the t r a n s p a s s i v e zone to the p a s s i v e zone.

The c h e m i c a l s t r u c t u r e of t h e s u r f a c e f i l m s d u r i n g t h e v a r i o u s s t a g e s of t h i s s h i f t were i n v e s t i g a t e d by Auger e l e c t r o n and X-ray pho toe l ec t ron s p e c t r o s c o p i e s .

The s h i f t of a s t a i n l e s s s t e e l specimen from t h e t r a n s p a s s i v e to the p a s s i v e zone was found t o be c h a r a c t e r i z e d by a s h a r p i n c r e a s e i n f i l m t h i c k n e s s (approx imate ly by a f a c t o r of four) a s w e l l a s an i n c r e a s e in the c o n c e n t r a t i o n r a t i o of the ox id ized t o m e t a l l i c s t a t e s of the i r o n ( F e + ' , F e + 2 / F e ° ) and chromium ( C r + 3 / C r ° ) p r e s e n t i n t h e f i l m . No d i s t i n c t s t r u c t u r e of t h e s u r f a c e f i l m s was o b s e r v e d i n t h e t r a n s p a s s i v e zone , whereas a l a y e r e d one was observed in the p a s s i v e zone. D i s t i n c t chromium su r f ace s e g r e g a t i o n was observed throughout the f i lm . Three l a y e r s were d e t e c t e d . At t h e m e t a l - f i l m i n t e r f a c e t h e l a y e r i s composed o f chromium oxide and m e t a l l i c i ron . Above i t the l a y e r i s composed of mixed i ron and chromium o x i d e s w i t h i r o n b e i n g p r i m a r i l y Fe . The o u t e r l a y e r i s a l s o composed of i r o n and chromium o x i d e s , and t h e i r o n i s m a i n l y F e + ^ . Cr + ° was not observed in t h e f i lm formed i n the t r a n s p a s s i v e zone. This i s in agreement with the e s t a b l i s h e d mechanism which proposes the d e s t r u c t i o n of p a s s i v e l a y e r s in t h i s p o t e n t i a l zone, i .e . by o x i d a t i o n of the i n s o l u b l e Cr -> t o s o l u b l e Cr ° compounds.

STUDIES OF METAL'-OXYGEN BONDS ON A l 8 £ ^ C r FERRITIC STAINLESS STEEL, IN THE PASSIVE AND TRANSPASSIVE ZONES, USING X-RAY PHOTOELECTRON SPECTROSCOPY M. Ben-Haim, U. Atzmony, N. Shamir and Y. Yahalom

The d e p t h p r o f i l e s of f i l m s formed on '\&%-Cr f e r r i t i c s t a i n l e s s s t e e l in the p a s s i v e and t r a n s p a s s i v e zones were i n v e s t i g a t e d u t i l i z i n g X-r a y p h o t o e l e c t r o n s p e c t r o s c o p y (XPS) and a n g l e r e s o l v e d XPS. Depth p r o f i l i n g (by s p u t t e r i n g ) was performed by a 2 keV Ar+ ion gun.

Technion, I s r a e l I n s t i t u t e of Technology, Haifa

100

Three main d i f f e r e n c e s between t h e p a s s i v e and the t r a n s p a s s i v e layers were revealed. a) The p a s s i v e l aye r i s about four t imes t h i c k e r than the t r a n s p a s s i v e

one. b) The i n t e g r a l M~OH t o M-0 bond concentration r a t i o i s very much higher

for the passive than for the t ranspassive zone. c) The d i s t r i b u t i o n p r o f i l e of M-0 and M-OH bonds i s app rox ima te ly

homogeneous over the depth of the t ranspass ive film (except for a s l i g h t OH enr ichment of the topmost l a y e r ) . The p a s s i v e l a y e r , on the o t h e r hand, exhibi ts a gradient of M-OH bond concentration with a maximum a t the topmost layer.

The M-OH g r a d i e n t i s i n v e r s e l y p r o p o r t i o n a l t o t h e a c t i v e s i t e concentration in films formed in the pass ive zone (for f i lms formed in the t ranspass ive zone, such a r e l a t i onsh ip cannot be derived). Consequently, M-oxygen p ro f i l e s can be used to character ize a c t i v e s i t e concentrat ions in films formed on s t a i n l e s s s t e e l surfaces.

PHASE TRANSITION IN SILICON-NITRIDE 0. Yeheskel and Y. Gefen

The phase t r a n s i t i o n in Si^N^ was analyzed on the bas is of data from v a r i o u s sources [ 1 - 5 ] . The da ta show t h a t t he a-*B phase t r a n s i t i o n i s enhanced by the a p p l i c a t i o n of e x t e r n a l p r e s s u r e on the a-Si^N^. Th is f ind ing i s in accordance with L e - C h a t e l i e r ' s p r i n c i p l e , s i n c e t h e molar volume of B-Si-,Njj, V„ , i s about O.H% h igher than V . C a l c u l a t i o n of the heat of transformation according to Clapyron's equation gives a value of 8.8 + 2 kJ /mol in the t empera tu re range 1650-1850K. Recen t ly i t was proposed [6] that th i s phase t r ans i t i on i s of a s o l i d - s o l i d nature. When s i n t e r i n g a d d i t i v e s to Si^N^ a re used to densify compacts, i t was suggested [*l] tha t the cf-6 phase t r ans i t ion occurs via the d i s so lu t ion -r e p r e c i p i t a t i o n model. F igure 10 shows the e f f e c t i v e p r e s s u r e between p a r t i c l e s in two c a s e s : (a) m a t e r i a l wi thout a d d i t i v e s and (b) m a t e r i a l with addi t ives . In case (b) the e f fec t ive pressure is lower than in case (a) due to the increase in contact area between the p a r t i c l e s .

The amount of g-SioN^ which is formed increases with the reduction of p a r t i c l e s i z e , which means an i n c r e a s e of con t ac t a r ea . The f a c t t h a t the formation of a s m a l l amount of l i q u i d due to a d d i t i v e s enhances the phase t r a n s i t i o n [3] i s exp l a ined by the b e t t e r t r a n s m i s s i o n of the pressure by the l iquid to the areas of contact. REFERENCES: [1] Yamada, T., Tanaka, A., Shinada, H. and Koizumi, M., Ceram. I n t . 8, 93

(1982). [2] Yamada, T., Shimada, M. and Koizumi, M., Am. Ceram. S o c B u l l . .60, 1225

(1981). [3] Yeheskel , 0., T a l i a n k e r , M., Gefen, Y., Mater. Sc i . Eng. J 8 , 209

(1986).

101

few nucleation sites

high effective • pressure

empty pores

(a)

many nucleation sites

low effective • pressure

(b)

liquid phase

Fig. 10

The effective pressure (stress) which is induced

in the particles due to the external force F:

(a) in a "dry" grain boundary

(b) in a "wet" grain boundary

102

[4] Bowen, L. J., Weston, R. J., Curruthers, T. G. and Brook, R. J., J.

Mater. Sci. j_3, 3 1 (1978).

[5] Yeheskel, 0., Mater. Sci. Eng. 7±, 371 (1985). [6] Yeheskel, 0., Gefen, Y., 3rd Israel Materials Engineering Conference,

Technion, Haifa, 1985, Abstract 9.1.2, in Hebrew.

THE INFLUENCE OF NITROGEN PRE-IMPLANTATION ON THE PROPERTIES OF He IMPLANTED

MATERIALS

Y. L i f s h i t z , E. Che i fe t z and S. Shamash The i n f l u e n c e of a s u r f a c e l a y e r of i m p l a n t e d n i t r o g e n on t h e

p r o p e r t i e s of t i t a n i u m h y d r i d e f u r t h e r implan ted by He was i n v e s t i g a t e d . S a m p l e s were i m p l a n t e d w i t h 45 keV N? i o n s / c m t o a t o t a l dose of 1.25x10 ' i o n s / c m a t room t e m p e r a t u r e . These s a m p l e s , a s w e l l a s i d e n t i c a l samples not i r r a d i a t e d by N2 i ons , were implan ted wi th He ions a t e n e r g i e s o f 25 keV a n d 45 keV t o d o s e s r a n g i n g f rom 2 x 1 0 1 ^ t o 5.5x10 ' ions/cm . He r e l e a s e from the implan ted samples was i nc r ea sed by a f ac to r of 2-4 in n i t r o g e n imp lan t ed samples . Ni t rogen i m p l a n t a t i o n a l s o induced s u r f a c e e r o s i o n and b l i s t e r i n g a t lower He f l u e n c e s than in samples n o t i r r a d i a t e d by N2 . I t seems t h a t r a d i a t i o n damage c a u s e d by N2

i m p l a n t a t i o n s u p p r e s s e s t h e p o s s i b l e enhancemen t of t h e i r r a d i a t i o n r e s i s t a n c e due to su r f ace n i t r o g e n a t i o n .

THE USE OF DCD FOR STRUCTURAL PROPERTIES CHARACTERIZATION OF SUBSTRATES AND LAYERS OF I I -VI COMPOUNDS

A. Raizman and H. Shaham A l l o y s of I I - V I compounds a re impor tan t semiconductors for i n f r a r e d

d e v i c e a p p l i c a t i o n s . S t r u c t u r a l i m p e r f e c t i o n s a r e c o n s i d e r e d t o be r e s p o n s i b l e for the low y i e l d and performance of i n f r a r e d d e v i c e s made of t h e s e m a t e r i a l s . The d o u b l e c r y s t a l d i f f r a c t o m e t e r (DCD) i s a p o w e r f u l t o o l for s t udy ing the c r y s t a l l i n e q u a l i t y of n e a r l y p e r f e c t c r y s t a l s . By a p p l y i n g t h i s t echn ique t o l a y e r s and s u b s t r a t e s of I I - V I compounds, t he fo l lowing r e s u l t s were o b t a i n e d .

a) Most of the CdTe (CT) and CdZnTe (CZT) s u b s t r a t e s taken from v a r i o u s sources have low angle grain boundaries.

b) The s t r u c t u r a l qua l i ty of HgCdTe (MCT) layers grown by the l i qu id phase epitaxy (LPE) method i s worse than that of the i r subs t ra t e s .

c) The number of d e f e c t s induced in HgZnTe e p i l a y e r s grown on CT and CZT subs t ra tes increases with increasing l a t t i c e mismatch between the layer and i t s underlying subs t ra te .

Two a d d i t i o n a l phenomena were measured and ana lyzed dur ing t h i s s tudy : a coheren t s t r a i n e d l a y e r of MCT grown on a CT s u b s t r a t e , and misorientation between an MCT layer and i t s CT subs t ra te .

Weizmann I n s t i t u t e of Science, Rehovot

103

NON-DESTRUCTIVE RAPID MEASUREMENT OF DOPANT DISTRIBUTION IN BigTe, BASED ALLOY

CRYSTALS

M. Sinvani

A new method for non-dest ruct ive measurement of the r e s i s t i v i t y d i s t r i bu t ion along semiconductor c ry s t a l ingots was developed. An apparatus based on this method was bui l t and used for characterization of the dopant distribution along crystal ingots (as grown) of thermoelectric mater ia l s . The c r y s t a l s were grown by the v e r t i c a l Bridgman technique. In these heavily doped semiconductor al loys, the e lec t r i ca l r es i s t iv i ty is related to the dopant concentration. By measuring the distribution of the e l e c t r i c a l r e s i s t i v i t y p( SL) along the ingot (l i s the distance along the growth axis) , one can obtain va luab le information about the growth conditions and the quality of the luaterial. p(&) is measured continuously and more accurately, with no need to c i t the ingot into smaller samples as in the previous method [1]. In Fig. 11 the distribucion p (f.) for a p-type Bi2Teo-Sb2Teg-Sb2SeQ ingot is given. From Fig. 11 one can ob\;air detailed information on the distribution of the dopant in the ingot.

I.5

T

0.5

0 0 I 2 3 4 5 6 7

I (cm)

Fig. 11 The distribution of the e lec t r i ca l res i s t iv i ty , p(£), for a p-type ingot,

measured by the new method

REFERENCE:

[1] Heikes, R.R. and Ure, J r . R.W., T h e r m o e l e c t r i c i t y - S c i e n c e and Engineering, Interscience, New York, 1961.

104

EVALUATION OF THE DISTRIBUTION COEFFICIENT OF SILICON IN CADMIUM USING RADIOACTIVE TRACERS H. Felds te in , R. Aharonovitz and 0. Even

I r r a d i a t e d s i l i c o n was d i s s o l v e d in molten cadmium and gradual ly s o l i d i f i e d . The d i s t r i bu t ion of the rad ioac t ive 31 Si along the Cd rod was determined by b e t a - c o u n t i n g . The d i s t r i b u t i o n c o e f f i c i e n t K of S i in Cd was ca lcu la t ed from the equation

Cx - C0R[(L-X)/L]K~1

where C i s t he Si c o n c e n t r a t i o n a t d i s t a n c e x from the s t a r t of s o l i d i f i c a t i o n , CQ i s the i n i t i a l a v e r a g e Si c o n c e n t r a t i o n , and L i s the t o t a l length of the Cd rod.

The e x p e r i m e n t a l r e s u l t s are p r e sen ted in Fig.12. The e s t ima ted value for K is 1.9 ± 0 .2 .

-2 -I ln(L-X)/L

Fig. 12 3 'S i be t a - ac t i v i t y as a function of the distance

from the end of the Cd rod

NEODYMIUM ION DISTRIBUTION IN Nd YAG CRYSTALS Y. Shimony, S. Biderman, Z. Goldbart and U. Laor

A YAG hos t c r y s t a l i s not amenable to uniform Nd'+ c o n c e n t r a t i o n . This problem a r i s e s as a r e s u l t of the c r y s t a l growth mechanism. An accurate a n a l y t i c a l method for the determination of Nd^+ concentration i s therefore required in order to charac te r ize Nd:YAG lase r rods.

In the p r e s e n t s tudy two a n a l y t i c a l methods were employed: s p e c t r o p h o t o m e t r y a n a l y s i s in the v i s i b l e range and ICP spec t roscopy . Acid d i s o l v e d Nd:YAG samples were used in order to de termine the Nd->

• • • • - • • • - • o +

concentrat ion, by the l a t t e r method. This enabled us to obtain the NdJ

concentration on an absolute sca le with the aid of c a l i b r a t i on curves. Results of the ICP spectroscopy measurements were obtained with much higher accuracy than that reported by any other method. These r e s u l t s served as calibrated standards for the other non-destructive analytical methods.

105

DIFFUSION OF Cd AND Hg IN LIQUID Te D. Eger, N. Yellin and L. Ben Dor

The diffusion coefficients (D) of Cd and Hg in liquid Te were measured at 465_1*950C. D was found to depend on concentration for concentrated solutions, and to have a minimum value for saturated solutions.

POSITIONAL AND ORIENTATIONAL ORDERING IN La(1 -x)Ga2(1 +xJ AND FORMATION OF LaGaL [1] L. Zevin , J . P e l l e g , G. Kimmel and D. Dayan

P o s i t i o n a l and o r i e n t a t i o n a l o r d e r i n g of Ga p a i r s , obse rved in t he La-Ga system, which l e a d s to the formation of a new co'mpound, LaGaj,, hav ing an or thorhombic c e l l , space group Pmmm, and l a t t i c e pa ramete r s aQ = 0.^3^ nm and Co = 0.441 mm. A s t r u c t u r a l r e l a t i o n e x i s t s be tween LaGa 2 , La^i - x ) G a 2 ( 1 + x ) , LaGag and Ga and t h e s t r u c t u r e o b t a i n e d d e p e n d s on t h e degree of s u b s t i t u t i o n of the La atoms by G a - l i k e m o l e c u l e s . REFERENCE: [ 1 ] Z e v i n , L., P e l l e g , J . , Kimmel, G. and Dayan, D., S c r . M e t a l l . J_8. 1257

(1981)).

PHASE TRANSFORMATIONS IN DILUTE U-Ti ALLOYS [ 1 ]

G. Kimmel, A. Landau, J . S a r i e l and U. Admon T i i s a s t a b i l i z e r o f t h e h i g h t e m p e r a t u r e Y-phase i n d i l u t e U-Ti

a l l o y s . A v a r i e t y of s t r u c t u r e s may be ob ta ined when samples a r e cooled from t h e y ~ P n a s e r e g i o n t o room t e m p e r a t u r e a t d i f f e r e n t r a t e s and unde r d i f f e r e n t c o n d i t i o n s [ 2 , 3 ] . We s t u d i e d t h e d e c o m p o s i t i o n modes of t h e Y - p h a s e of U-3.7 a t ? Ti a l l o y , a t s e v e r a l i s o t h e r m a l h e a t t r e a t m e n t s f o l l o w e d by q u e n c h i n g t o room t e m p e r a t u r e . SEM and XRD t e c h n i q u e s were employed.

The t h e r m a l t r e a t m e n t s were of t h r e e t y p e s . In t h e f i r s t t h e i s o t h e r m a l t e m p e r a t u r e was in t h e 660 -710°C r a n g e , where t h e e u t e c t o i d r e a c t i o n y -+ B+<$ t a k e s p l a c e . I n t h e s e c o n d , a t T of 5 0 0 - 6 1 0 ° C , t h e r e a c t i o n i s Y •*• «+5. The t h i r d t r e a t m e n t was water quenching in which y t r ans forms i n t o a ' , a s u p e r s a t u r a t e d s o l i d s o l u t i o n hav ing a d i s t o r t e d a~U s t r u c t u r e .

The g r a i n m o r p h o l o g y was s t r o n g l y a f f e c t e d by t h e t r e a t m e n t employed. Trea tments of the f i r s t type r e s u l t e d in a l a m e l l a r p e a r l i t i c s t r u c t u r e , showing a d i s t i n c t phases s e p a r a t i o n . Trea tments of the second type gave a f i ne d i s p e r s i o n of 6 p r e c i p i t a t e s , coherent and a c i c u l a r a f t e r s h o r t t i m e s and s p h e r o i d a l a f t e r l o n g e r t i m e s . T r e a t m e n t s o f t h e t h i r d t y p e y i e l d e d a c o a r s e , a c i c u l a r and homogeneous s t r u c t u r e . The t h r e e morpho log ica l types show resemblance t o p e a r l i t e , b a i n i t e and m a r t e n s i t e in

Hebrew U n i v e r s i t y , Je rusa lem Ben-Gurion U n i v e r s i t y of the Negev, Beer-Sheva

106

s t e e l s , r e spec t ive ly , seen in Fig. 1 3.

The X-ray difractograms from these s t ruc tu res are

Martensite

Baini te

Pea r l i t e

( 0 ) 20

11

112

<£

I 0 parameters

a • 2.868

b = 5.833

c * 4.970

022 1 I . ^ _J

a « 2.855

b « S.854

c - 4.955

022

a • 2.851

b •= 5.864

c • 4.968 11.1

1 022 1 JUL^_^^_^J

00?

1

l ^jJ

1J.0

10.1

Uil y

U21

no

J

020

|

020

I 1 00.1 1 lOZO

I U

Fig. 13 The X-ray diffractograms

Q u a n t i t a t i v e XRD a n a l y s i s of samples a f t e r t he se t r e a t m e n t s indicated that the t i tanium s o l u b i l i t y in the a phase is higher than in the 6 phase. However, there i s some controversy in the l i t e r a t u r e regarding

t h i s ques t i on [ I ] . We th ink t h a t t h i s c o n t r o v e r s y may be due to the k ine t i c s of the transformations involved. In order to find out which phase d i s so lves more titanium, a fourth type of heat treatment was carr ied out. Martensi t ic samples were heated from room temperature to a temperature in the cxorB r e g i o n s , he ld for 24 hours and then water quenched. XRD ana lys i s supported by SEM observat ions c l e a r l y showed that the s o l u b i l i t y of t i t a n i u m in the gphase i s h ighe r than in the a phase. REFERENCES: [1] Kimmel, G., Landau, A., S a r i e l , J . and Admon, U., J . Ul t ramicroscopy

H , 375 (1981). [2] Echlemeyer, K. H. and Zanner, F. J., J . Nucl . Mater. 67, 33 (1977).

107

[3] Bar-Or, A., Kimmel, G., Tomer, A. and Zahav i , A., in the p roceed ings of An I n t e r n a t i o n a l Conference on S o l i d to S o l i d Phase Transformat ion , Carnegie-Mellon Universi ty, Pit tsburgh, PA August 1981, Meta l lu rg ica l S o c i e t y of AIME, New York, 1982, p. 1049.

[4] Knapton, A,G., J . Inst. M e t a l s 83 , 497 (1955),' d i s c u s s i o n , 8_4, 532 (1956).

108

A TIME OF FLIGHT SYSTEM FOR POLARIZATION MEASUREMENT OF PHOTONEUTRONS FROM THE 2H(Y,n) REACTION

A. Wolf, Z. Berant, Y. Birenbaum, S. Kahane and R. Moreh The p o l a r i z a t i o n of photoneut rons from the H(y,n) r e a c t i o n i s

considered Cl] to be a s e n s i t i v e probe for the existence of meson exchange c u r r e n t s (MEC) in the n-p system. This s e n s i t i v i t y i s known t o be h ighe r a t low -y-energies, in the range of 6-11 MeV. An e x p e r i m e n t a l system was set up to measure the photoneutron po la r iza t ion using neutron-capture gamma rays of 7.6 MeV and the time of f l igh t technique.

The t a r g e t c o n s i s t e d of 20 g of d e u t e r a t e d s c i n t i l l a t o r (NE-232), coupled to a fast photoraul t i p I t e r . The photoneutrons were sca t te red by a carbon analyzer placed at 90° with respect t o the incident gamma beam and 25 cm away from the ta rge t , and detected in two NE-213 l iqu id s c i n t i l l a t o r s placed a t +50°, -50° with respect to the ta rge t -ana lyzer axis . The s t a r t and s top s i g n a l s for the t ime of f l i g h t system were p rov ided by the p h o t o m u l t i p l i e r s a t t a c h e d to the d e t e c t o r s and t a r g e t s c i n t i l l a t o r s , r e spec t ive ly . The t o t a l f l i g h t path was 50 cm.

A preliminary r e s u l t for the photoneutron po la r iza t ion was obtained: P = -0.065tO.0il0. This value i s consistent with previous measurements [1] a t e n e r g i e s around 8 MeV, and i s in good agreement wi th P a r t o v i ' s c a l c u l a t i o n s in which no meson exchange c u r r e n t s were inc luded . The inclusion of MEC is expected [2] to give P = -0.12. More accurate r e s u l t s are needed before we can c l e a r l y dis t inguish between the two ca l cu l a t i ons . REFERENCES: [1] H o l t , R. J . , Stephenson, K. and Specht, J . R., Phys. Rev. L e t t . J50, 577

(1983). [2] Hadjimichael, E., Phys. Le t t . 16B, 147 (1973).

A THREEr.DETECTOR SYSTEM FOR PERTURBED ANGULAR CORRELATIONS Z. Berant and A. Wolf

The per tu rbed a n g u l a r c o r r e l a t i o n (PAC) t echn ique can be used t o study phase t r a n s i t i o n s of hydrogen-metal systems through the PAC measurement of a probe n u c l e u s l i k e 1 1 1 I n or 1°1Hf. Any change in the amount and location of the hydrogen atom in the metal matrix w i l l cause a change in the e l e c t r i c f i e l d gradient , and w i l l consequently affect the PAC pa t te rn .

A t h r e e - d e t e c t o r system was s e t up for a n g u l a r c o r r e l a t i o n measurements. The system cons i s t s of three Nal 2"x2" de tec to r s attached to fast photomul t ip l ie rs and a conventional fast-s low coincidence system. The time reso lu t ion a t 511 keV i s about 2 nsec FWHM. The experimental system was checked by measuring the a n g u l a r c o r r e l a t i o n s of the 1173-1333 keV cascade in °°Co, and the 122-24H keV cascade in 1^2E u > Both cascades have a 4 ~2 - 0 + sp in sequence. The r e s u l t s a re in good agreement with the t h e o r e t i c a l predict ion for t h i s spin sequence. A var ie ty of hydrogen-metal compounds wi l l be studied using th i s technique.

1 11

http://-0.065tO.0il0

EFFECTIVE g FACTORS AND PROTON-BOSON NUMBERS IN THE VICINITY OF PROTON SUBSHELL CLOSURES [1 ] A. Wolf, D.D. Warner* and N. Benczer -Kol le r**

New e x p e r i m e n t a l r e s u l t s on g f a c t o r s of 2 1 s t a t e s w e r e a n a l y z e d t o g e t h e r w i th e x i s t i n g da ta in t h e Ba-Dy r eg ion . A s imp le r e l a t i o n , based on c o n s t a n t v a l u e s of the p ro ton and neu t ron boson g f a c t o r s , can d e s c r i b e a b r o a d r a n g e of n u c l e i . M o r e o v e r , t h e e x t r a c t e d v a l u e s of t h e p r o t o n , n e u t r o n b o s o n g f a c t o r s y i e l d a much i m p r o v e d d e s c r i p t i o n o f t h e B(M1) s t r e n g t h s t o t he newly d i s c o v e r e d c o l l e c t i v e i s o v e c t o r e x c i t a t i o n s in the r a r e e a r t h r eg ion . The anomalous v a l u e s of g ^ ) t h a t occur in t he r eg ion of t h e Z=6M s u b s h e l l c l o s u r e were d e s c r i b e d i n t e r m s of c h a n g e s i n t h e e f f e c t i v e number of p ro ton bosons ^% which t ake p a r t in t he c o l l e c t i v e motion, and the deduced v a l u e s of N® a r e compared wi th r e c e n t microscopic c a l c u l a t i o n s . REFERENCE: [1 ] Wolf, A, Warner, D.D., B e n c z e r - K o l l e r , N. , Phys. L e t t . 158B, 7(1985)

PHOTOFISSION OF 2 3 8 U WITH NEUTRON-CAPTURE GAMMA RAYS

S. Kahane and A. Wolf F i s s i o n y i e l d s from t h e p h o t o f i s s i o n of 2 ^°U w i t h n e u t r o n c a p t u r e

"Y-rays were measured a t an e f f e c t i v e e x c i t a t i o n energy Ex=7.8 MeV. The mass

d i s t r i b u t i o n of the f i s s i o n fragments was deduced by measuring y i e l d s of 19 mass c h a i n s w i t h r e s p e c t t o 1 3 ^ X e , whose c u m u l a t i v e y i e l d was measured d i r e c t l y . The r e s u l t s a r e i n g e n e r a l a g r e e m e n t w i t h t h o s e o b t a i n e d by J a c o b s e t a l . [ 1 ] u s i n g b r e m s s t r a h l u n g a t h i g h e r e n e r g i e s . However, a s y s t e m a t i c dec rease in the y i e l d s of a few mass c h a i n s was observed . This dec rease can be a t t r i b u t e d t o a change in the shape of the l i g h t and heavy mass d i s t r i b u t i o n s , a s a func t ion of energy.

The r a t i o Iv/Tf was measured a t two e n e r g i e s and i t s v a l u e s confirm r e c e n t t h e o r i e s on t h e s h a p e and h e i g h t of t h e s e c o n d f i s s i o n b a r r i e r i n 2 3°U. The most p r o b a b l e c h a r g e Z was o b t a i n e d fo r t h e mass c h a i n s : 9 2 , 131*. 135 a t t h r e e e n e r g i e s . REFERENCE:

[ 1 ] J a c o b s , E., T h i e r e n s , H., D e f r e n n e , D., De C l e r q , A., D^hondt , P . , De G e l d e r , P. and D e r u y t t e r , A. J . , Phys . Rev. C j_9, H22 (1979) .

MEASUREMENT OF SECONDARY NEUTRON ENERGY SPECTRA FROM (n ,2n) REACTIONS U. German and G. Shani

The e x p e c t e d n e u t r o n e n e r g y s p e c t r a of t h e s e c o n d a r y n e u t r o n s e m i t t e d f rom ( n , 2 n ) and ( n , 3 n ) r e a c t i o n s a r e m o s t l y e v a l u a t e d t h e o r e t i c a l l y , based on the e v a p o r a t i o n model from a compound n u c l e u s . The

Brookhaven National Laboratory, Upton, NY, U.S.A.

Rutgers University, Piscataway, NJ, U.S.A. tt £ tt


1 1 2

p r e - c o m p o u n d e f f e c t h a s i n c r e a s i n g l y b e e n i n t e g r a t e d i n t h e m o d e l t o e x p l a i n d e v i a t i o n s between measured and c a l c u l a t e d c r o s s s e c t i o n s .

An e x p e r i m e n t a l system was employed which c o n s i s t s of 3 d e t e c t o r s ope ra t ed in co inc idence w h i l e a sample p l aced a t i t s c e n t e r i s i r r a d i a t e d b y a 11.7 MeV n e u t r o n beam. S a m p l e s of d i f f e r e n t m a t e r i a l s u n d e r g o i n g (n,2n) r e a c t i o n s were used. For background d e t e r m i n a t i o n a g r a p h i t e sample was p l a c e d i n t he spec t rome te r w i th t h e a c c e l e r a t o r running under s t a n d a r d c o n d i t i o n s .

The bu lk of the n e u t r o n s b e l o n g to t he e v a p o r a t i o n group and e x h i b i t a t y p i c a l Maxwel l ian d i s t r i b u t i o n . However, t h e r e i s a p o s s i b l e i n d i c a t i o n of the p resence of a n o t h e r group of n e u t r o n s wi th ha rde r e n e r g i e s which can be a t t r i b u t e d t o the pre-compound r e a c t i o n mechanism. The p r e s e n c e of t h i s n e u t r o n g r o u p i s f e a s i b l e from t h e t h e o r e t i c a l p o i n t of v i e w and was i n d i c a t e d a l s o in o t h e r e x p e r i m e n t a l works .

INFLUENCE OF THE GIANT DIPOLE RESONANCE STRUCTURE ON ELASTIC GAMMA-RAY SCATTERING FROM 2 0 9 B i

S . Kahane I t i s a r g u e d i n t h i s work .... t i n a n a l y z i n g e l a s t i c gamma-ray

s c a t t e r i n g c r o s s s e c t i o n s , s t r u c t u r e i n t h e low e n e r g y t a i l of t h e g i a n t d i p o l e r e sonance (GDR) has t o be c a r e f u l l y accounted for . An a p p l i c a t i o n was made to r e c e n t e l a s t i c s c a t t e r i n g measurements from 2 0 9 B i , performed by R u l l h u s e n e t a l . [ 1 ] . B e t t e r a g r e e m e n t i s o b t a i n e d w i t h e x p e r i m e n t when t h e s t r u c t u r e of the GDR i s s p e c i f i c a l l y i n c l u d e d in the c a l c u l a t i o n s . REFERENCE: [ 1 ] R u l l h u s e n , P . , Z u r m u h l , U., Smend, F . , Schumache r , M., B o r n e r , H. G.

and K e r r , S. A., P h y s . Rev. C 2 7 , 559 ( 1 9 8 3 ) .

STUDY OF THE ORIENTATION OF ADSORBED N20 MOLECULES USING NUCLEAR RESONANCE FLUORESCENCE

R. Moreh and 0 . Shahal A n u c l e a r t e c h n i q u e u t i l i z i n g t h e r e s o n a n c e s c a t t e r i n g o f

monoenerget ic photons from the 6321 keV l e v e l i n ^N was used for s t u d y i n g the o u t - o f - p l a n e o r i e n t a t i o n [ 1 ] of t he l i n e a r m o l e c u l e N20 wi th r e s p e c t t o an a d s o r b i n g g r a p h i t e s u r f a c e i n t h e form of G r a f o i l . T h i s t e c h n i q u e moni tors the Doppler b roadening of the 6321 keV l e v e l of -*N a r i s i n g from t h e z e r o - p o i n t v i b r a t i o n s of t h e N20 n o r m a l modes . The v i b r a t i o n s a r e h i g h l y a n i s o t r o p i c r e s u l t i n g in an a n i s o t r o p i c Doppler b roaden ing a l o n g and p e r p e n d i c u l a r t o t he N20 m o l e c u l e . This f a c t was used for mon i to r ing t h e o r i e n t a t i o n of t h e a d s o r b e d N20 m o l e c u l e w i t h r e s p e c t t o t h e g r a p h i t e p l a n e s , by comparing the s c a t t e r e d i n t e n s i t y of t h e 6321 keV photons from an N 2 0 - G r a f o i l s a m p l e where t h e g a s was i n t h e form 1 5 N - 1 ^ N - 0 (99$ 1 5 N ) . The r e s o n a n t l y s c a t t e r e d p h o t o n i n t e n s i t i e s from two g e o m e t r i e s o f t h e s a m p l e (where t h e y-beam was p a r a l l e l and p e r p e n d i c u l a r t o t h e g r a p h i t e p l anes ) were measured in the t empera tu re range 300K-20K.

113

The r e s u l t s i n d i c a t e t h a t t he NOg molecu le p r e f e r s a p a r a l l e l or ien ta t ion r e l a t i v e to the graphite planes and tha t t h i s behavior is c l ea r even at temperatures as high as 240K. REFERENCE: [1] Noreh, R. and Shahal, 0 . , Phys. Rev. Le t t . 43, 1943 (1979).

ORIENTATION OF NITRATE MOLECULES IN GRAPHITE~HN03 RESIDUE COMPOUNDS R. Moreh, 0. Shahal and G. Kimmel

Using nuclear resonance fluorescence of 6.324 MeV photons from 15N, we showed t h a t i n t h e 3 rd s t a g e g r a p h i t e - H N O , r e s i d u e compounds (characterized by a distance I , = 13.25 A), the in te rca lan t molecules are in the form of n i t r a t e s and are oriented at 60 = 15 + 5° to the graphite planes. The procedure for preparing and character iz ing thick residue samples using highly oriented pyrolytic graphite was considered.

114

PHOTOLYTIC AND DARK REACTIONS IN GASEOUS MIXTURES OF CHgO, 0 2 , AND MeOH AT 373K [1] A. Horowitz

The effect of methanol addit ion on hydrogen formation in the 3130 A photolysis of 0 2 - l ean CH20-02~Me0H mixtures was studied at 373 K. Addition of MeOH to the CH20-02 systems lowers both the r a t e s and the quantum y ie lds of t h e c h a i n - f o r m e d h y d r o g e n . A r e v e r s i b l e da rk r e a c t i o n , CH20 + MeOH 2 p roduc t , for which a v a l u e of K20 = (4.3 + 0.3)x102 t o r r was determined, was found to be the cause of the d r a s t i c reduction in RH . The product of t h i s r e a c t i o n presumably i s the a c e t a l HOCH2OCH,. The a s s u m p t i o n t h a t $H i s r e d u c e d a s a r e s u l t of t h e r e a c t i o n H + 0 2 + MeOH - - > H02 + MeOH l e a d s t o an e s t i m a t e d k 1 5 v a l u e of (9.1 + 1.4)x101 0 M"2 s~1. REFERENCE: [1] Horowitz, A., J . Phys. Chem. 89, 1764 (1985).

EXCIMER LASER PHOTOLYSIS STUDIES OF PHOTOINDUCED AGGREGATION IN POLYMERS CONTAINING SPIROPYRAN UNITS [1] Y. Kalisky and D. J . Williams*

To determine whether t h e r e i s a r e l a t i o n s h i p between photoinduced conformat iona l changes in polymers c o n t a i n i n g sp i ropyran u n i t s and photoinduced p roces ses l e a d i n g to spontaneous agg rega t ion in I-A and II-A [ 1 ] , we have conducted a t i m e - r e s o l v e d study of homopolymer and copolymer so lu t ions [2 ] ,

Transient absorption spectra were obtained with a pulsed N2 l a s e r and d e t e c t i o n system. The l a s e r was a Lumonics Te-86 1S excimer l a s e r o p e r a t i n g on a N~-He mixture a t 337.1 nm with a pu l s e width of 3 nsec (FWHM). The maximum measured pu l s e energy a t the sample was 170 mJ/cm , and lower energies were frequently used. A l l measurements were performed a t ambient t empera tu re and N was bubbled through the sample for s e v e r a l minutes pr ior to and during the measurements.

The t r ans ien t absorption spectra of a monomer so lu t ion of SP and of the copolymer solut ion of SP were observed. Assignment of the t r ans i en t s formed on lase r exposure was performed based on these spectra.

A s h o r t - l i v e d t r a n s i e n t X(<10 nsec) superimposed on the t r i p l e t absorption was detected in toluene so lu t ions of the monomer, polymer, and homopolymer. The decay of X i s fo l lowed by formation of a r ing-opened long- l ived t r ans ien t B peaking at 550 nm within 300 psec, while the decay of the t r i p l e t s t a t e of SP i s followed by a dimer AB formation peaking a t 6H0 nm. A r e d - s h i f t e d s h o u l d e r on the AB a b s o r p t i o n band i s a s s o c i a t e d with a slow-forming aggregation in the monomer and copolymer so lu t ions . The decay of the polar t r ans ien t X and the associated buildup a t 550 nm were

Eastman Kodak Co., Rochester, U.S.A.

117

slower in the homopolymer so lu t ion and in a polar so lvent ( ace ton i t r i l e ) than in a toluene so lu t ion of SP.

A general model to account for the photoprocesses occurring in the copolymer ( s o l i d l i n e s ) and homopolymer (dashed arrow) i s proposed according to the following scheme.

kn \

[A] •> AB

t

i

<AB

k. ISC

£ ' A* (X'or A') . \

B

\ k B

B h*>

AB, •> ABnor(AmB)n

A l a s e r t i m e - r e s o l v e d t r a n s i e n t a b s o r p t i o n s tudy was made of the photoprocesses occurring in polymer and monomer so lu t ions of SP for be t t e r unde r s t and ing of the format ion of the a g g r e g a t i o n and q u a s i - c r y s t a l processes. We showed tha t intrachain complexing of the t r i p l e t s t a t e of SP with the ground s t a t e chromorphore l e a d s to i n t r a c h a i n complexes AB. Aggregation of AB uni t s or A un i t s a l so occurs at much longer times and is r e d s h i f t e d . S t e r i c e f f e c t s in t h e p o l y m e r s o l u t i o n r e t a r d t h e isomerization of X and prevent complexing to AB. REFERENCES: [1] Kalisky, Y. and Williams, D. J., in: Conference on Lasers and E lec t ro -

Optics (CLEO '85), Baltimore, MD, 1985, Abstract WC3. [2] Kalisky, Y. and Williams, D. J . , Macromoleoules V£, 2 9 2 Cl98M).

AN IRIDIUM-BIPYRIDINE COMPLEX AS A PHOTOSENSITIZER FOR THE BROMIDE OXIDATION TO BROMINE BY OXYGEN [1]

# # # &# A. Slama-Schwok , S. Gershuni , J . Rabani , H. Cohen and D. Meyerstein

An i r i d i u m ( I I I ) - b i p y r i d i n e complex, [ I r t C ^ N ' - b p y M b p y ^ ] , was used as a p h o t o s e n s i t i z e r in aqueous bromide s o l u t i o n s . S t e a d y - s t a t e photolysis of oxygenated so lu t ions by n e a r - u l t r a v i o l e t and v i s i b l e l i gh t produces equal concentrations of Br,"and H202. The quantum y i e l d of Br?" equiva len ts depends on pH, i l luminat ion dose, and bromide concentration. The i n i t i a l y i e l d ( e x t r a p o l a t e d ) r eaches a v a l u e of 0.08. A mechanism i n v o l v i n g two e x c i p l e x e s and the t r a n s i e n t s B r ^ - ' and H0~ i s proposed,

* * Hebrew Universi ty, Jerusalem Ben-Gurion University of the Negev, Beer-Sheva

1 18

b a s e d on p r o d u c t s a n a l y s i s , s t e a d y - s t a t e e m i s s i o n , and p u l s e d l a s e r e x p e r i m e n t s . REFERENCE:

CI3 S l a m a - S c h w o k , A., G e r s h u n i , S . , R a b a n i , J . , C o h e n , H. and M e y e r s t e i n , D., J . P h y s . Chem. 89 , 2460 (1985).

REDUCTION OF THE [ ( N H ) - 2 , 2 , - B I P Y R I D - 3 - Y L I U M - C 3 , N , ] B I S ( 2 , 2 , - B I P Y R I D I N E -N,N')IRIDIUM(III) TRICATION IN AQUEOUS SOLUTIONS: A PULSE RADIOLYTIC STUDY [1 ] H. Cohen, A. Slama-Schwok , J . Rabani , R. J . Watts and D. Meyers te in

The s p e c i f i c r a t e s of r e d u c t i o n of t h e t i t l e complex by e a and .C(CHo)20H r a d i c a l s were determined. The reduced complex t h u s produced a t pH 0.5 h a s an a b s o r p t i o n s p e c t r u m w i t h X m a x = 395 t. 5 nm, e

m a x = 10600 M_1 cm - 1 , and a s h o u l d e r a r o u n d 150 nm. T h i s r e d u c e d s p e c i e s h a s a pK v a l u e of about 0.9 and i s r e l a t i v e l y s t a b l e in t he absence of o x i d a n t s . I t decays wi th a h a l f - l i f e ^.100 s, and i t s decomposi t ion r e a c t i o n i n v o l v e s w a t e r r e d u c t i o n w i t h e v o l u t i o n of d i h y d r o g e n . T h i s r e d u c e d c o m p l e x i s o x i d i z e d by 0 2 and B r 2 ~ - a t r a t e s a p p r o a c h i n g t h e d i f f u s i o n - c o n t r o l l e d l i m i t . REFERENCE:

[1] C o h e n , H., S l a m a - S c h w o k , A., R a b a n i , J . , W a t t s , R. J . and M e y e r s t e i n , D., J . Phys . Chem. 89 , 2*465 (1985).

KINETICS OF g-HYDROXYL ELIMINATION FROM [(PR0TOP0RPHYRIN)Fe(III)-CHRCH2OH] IN

AQUEOUS SOLUTIONS. A PULSE RADIOLYTIC STUDY

Y. Sorek, H. Cohen and D. Meyers te in The r e a c t i o n s of i r o n ( I I ) p r o t o p o r p h y r i n , F e ( I I ) P P , w i t h t h e f r e e

r a d i c a l s •CHRCH20H (R = H.CH,) were s t u d i e d . F e ( I I ) P P r e a c t s w i t h b o t h r a d i c a l s , t h e p r o d u c t b e i n g a s h o r t - l i v e d t r a n s i e n t w i t h a m e t a l - c a r b o n bond.

Fe ( I I )PP + .CHRCHgOH > Fe(III)PP-CHRCH20H.

These t r a n s i e n t s decompose in p r o c e s s e s obeying f i r s t o rde r r a t e laws, wi th k = 80 + 10 and 40 ± 10 f o r R = H and CH, r e s p e c t i v e l y , i n t h e pH r a n g e 10-13. The p roduc t s of t h e s e r e a c t i o n s a r e Fe(I I I )PP and the co r r e spond ing a l k e n e . I t i s t h e r e f o r e c o n c l u d e d t h a t t h e d e c o m p o s i t i o n r e a c t i o n s observed a r e Fe(III)PP-CHRCH20H > Fe(II I )PP + CHR = CH2 + 0H~.

Hebrew U n i v e r s i t y , J e rusa l em U n i v e r s i t y of C a l i f o r n i a , San ta Barbara , CA, U.S.A. Ben-Gurion U n i v e r s i t y of the Negev, Beer-Sheva

119

STABILIZATION OF MONOVALENT NICKEL IN AQUEOUS SOLUTIONS BY COMPLEXATION WITH THE g-ISOMER OF C~5, 1 2H?ACEMIC-1,4,5,7,7,8,11,12,1 4,l4-DECAMETHYLr*1 ,4,8,11 -TETRAAZACYCLO--TETRADECANE N. Jubran , H. Cohen and D. Meyers te in

The m o n o v a l e n t n i c k e l complex f ramed by t h e r e d u c t i o n o f t h e B - i s o m e r o f t h e c o m p l e x of C-5 ,1 2 - r a c e m i c - 1 , 4 , 5 , 7 , 7 , 8 , 1 1 ,12 ,1 4,1 4 -d e c a m e t h y l - 1 , 4 , 8 , 1 1 - t e t r a a z a c y c l o t e t r a d e c a n e n i c k e l ( I I ) , NiL^c i n 0.1 M HC02Na, pH 7.6 has a h a l f - l i f e l onge r than 90 hours . The redox p o t e n t i a l of the coup le NiL 1

+ /N iL 12 + i s -0.94 V v s . Ag/AgCl. The a b s o r p t i o n spectrum

of N i L ^ c o n s i s t s of a band w i t h *-max = 335 nm and zmax = 2200 M~1 cm" 1 . For t h e a n a l o g o u s complex w i t h C - 5 , 1 2 - r a c e m i c - 5 , 7 , 7 , 1 2 , l 4 , l 4 - h e x a m e t h y l -1 ,4 ,8 ,1 1 - t e t r a a z a c y c l o t e t e t r a d e c a n e , L 2 , t h e h a l f - l i f e of NiL 2 i s l e s s t h a n 1 min and t h e r e d o x p o t e n t i a l i s - 1 .44 V v s . Ag/AgCl. These r e s u l t s a r e s i m i l a r t o those r e p o r t e d e a r l i e r for the ana logous n i c k e l complexes wi th t h e meso-isomers of the l i g a n d s . The r e s u l t s t hus i n d i c a t e t h a t bo th t h e k i n e t i c and t h e r m o - d y n a m i c s t a b i l i z a t i o n of monovalent n i c k e l by N-m e t h y l a t i o n of t e t r a z a m a c r o c y c l i c l i g a n d s i s no t s i g n i f i c a n t l y a f f e c t e d by t h e c o n f i g u r a t i o n of the l i gand .

KINETICS OF FORMATION AND DECOMPOSITION OF THE METHYLKIOPPER(II) COMPLEX IN AQUEOUS SOLUTIONS. A PULSE RADI0LYSIS STUDY

H. Cohen and D. Meyers te in M e t h y l r a d i c a l s r e a c t w i t h C u t „ i n a q u e o u s s o l u t i o n t o y i e l d

CuCHJj kCu+ +_CH = 3.5x10y M ' s ' . CuCH^ decomposes a t pH > 2.5 v i a 2CuCH*ar i —> 2Cu* + C~Hfi> 2k = 1 .8x10 7 M 1 s " 1 and a t pH < 2.5 v i a + -5aq «tq _ <s o o - i CuCH3 + HoO —> Cu^ + CHij, k o b = 2 .0x10^3 ' a t pH 1.0. The s p e c t r u m of CuCHt h a s Xfnax = 380 nm and e m a x = 2200 M~1cm~1. T h i s band i s a s s igned to a LMCT t r a n s i t i o n .

e ; \ , A PROBE FOR THE TITRATION OF PROTEINS' ACTIVE-SITE HISTIDINES+ [1 ] a q g £ %£ $ $

J . Ste iner , M. Faraggi, M. H. Klapper and L. M. Dorfman In p r e v i o u s s t u d i e s [2 ,3] we have a t tempted to measure p r o t e i n

h i s t i d i n e pKs with e~ as a probe. We have obta ined unexpected r e s u l t s : (a) imidazo le r e d u c t i o n in a -chymotryps in and t r y p s i n a t low pH; (b) no r e d u c t i o n w i th t h e i r r e s p e c t i v e p r e c u r s o r s , chymotrypsinogen and t ryps inogen , a t any pH; (c) no imidazole r educ t ion in lysozyme, with i t s lone h i s t id ine located a t the protein surface and not at i t s a c t i v e s i t e ; (d) h i s t i d i n e r e d u c t i o n in RNase-A with a measured h i s t i d i n e pK 5.9, a v a l u e near the pKs of the a c t i v e s i t e h i s t i d i n e s of t h i s enzyme; (e) no r e a c t i n g h i s t i d i n e a s s o c i a t e d with the pK near 7 in any of these enzymes. In explanation, we have suggested that e~ i s specif ic to those h i s t i d ines

This work was performed a t Ohio Sta te University, Columbus, OH, U.S.A. Ben-Gurion University of the Negev, Beer-Sheva Ohio State University, Columbus, OH, U.S.A.

120

found a t enzyme a c t i v e s i t e s . In o r d e r t o v e r i f y t h i s p r o p o s e d spec i f i c i ty , we extended our s tudies of the e~ to addi t iona l pro te ins and protein de r iva t i ve s .

The one e lec t ron reduction of protein h i s t i d i n e s , iden t i f ied by tne appearance of an a b s o r p t i o n band cen te red near 360nm, was observed upon react ion of e~ with 6-chymotrypsin, s u b t i l i s i n BPN*, s u b t i l i s i n Carlsberg, t h i o s u b t i l i s i n , papain and the i n a c t i v e methyl m e t h a n e t h i o s u l f o n a t e modified papain. With papain the y i e ld of the imidazole-electron adduct i s constant from pH 5.1 to pH 8.2. For the remaining proteins the absorbance y i e l d i s pH dependent with apparen t pKs below 5 for 6-chymotrypsin, near 6.3 for the s u b s t i l s i n s and 5.6 for the modified papain. There i s l i t t l e or no h i s t i d ine reduction a f t e r the react ion of e with three chymotrypsin d e r i v a t i v e s modified cova l en t ly a t the ac t i ve s i t e , (phenylmethylsulfonyl) chymotrypsin, [67 -N-methylhist idine] chymotrypsin and anhydroehymotrypsin. Nor i s s i g n i f i c a n t imidazo le r e d u c t i o n seen with (phenylmethylsulfonyl) s u b t i l i s i n BPN' and with n a t i v e s u b t i l i s i n in the presence of competitive i n h i b i t o r b o r i c ac id . We concluded t h a t the s o l e or primary h i s t i d i n e reduced was t h a t a t the a c t i v e s i t e , wi th r e d u c t i o n o c c u r r i n g a f t e r mig ra t ion of the e l e c t r o n from one or more i n i t i a l a t t achment s i t e s (probably carbonyls) elsewhere on the protein. REFERENCES: [1] S t e i n e r , J . , F a r a g g i , M., K l a p p e r , M. H. and Dorfman, L.M.,

Biochemistry 2±, 2139 (1985). [2] Fa ragg i , M.f Klapper , M. H. and Dorfman, L. M., J. Phys. Chem. 82, 508

(1978). [3] Fa ragg i , M., Klapper , M. H. and Dorfman, L. M., Biophys. J . 2H_, 307

(1978).

INTRAMOLECULAR ELECTRON TRANSFER IN PROTEINS4" [1]

M. Faraggi, J. Steiner and M. H. Klapper

Our e a r l y r e s u l t s in h i s t i d i n e ( s ) - c o n t a i n i n g p r o t e i n s led us to consider the p o s s i b i l i t y of e lec t ron migration within proteins [2-H] and we managed to c o l l e c t c i rcumstant ia l evidence for such t ransfer [ 5 ] . Since then, there have been observat ions of long range e lec t ron t ransfer in model systems and p r o t e i n s . In t h i s work we p r e s e n t two more examples of e lec t ron migration. In the f i r s t we observe that COJJ reduces the f l av in group in RBP to the semiquinone form, but that t h i s reduction occurs almost one order of magnitude more slowly than the react ion of the formate r ad ica l with the p r o t e i n ; i . e . , most of the CO^ i s gone from the s o l u t i o n before an appreciable amount of the f l a v i n has reacted. We have shown tha t t h i s f l a v i n r e a c t i o n has both f i r s t and second order components, and have proposed t h a t the f i r s t o rde r p rocess i s due to i n t r a m o l e c u l a r e l e c t r o n t ransfer react ion, the e lec t ron acceptor being the f l a v i n group, and the

+This work was performed a t Ohio Sta te University, Columbus, OH, U.S.A. Ohio Sta te University, Columbus, OH, U.S.A.

121

donor an a s y e t u n i d e n t i f i e d r a d i c a l ( p o s s i b l y an e l e c t r o n a d d u c t on a c a r b o n y l ) , produced on the p r o t e i n in the i n i t i a l COg r e a c t i o n . There a r e no X - r a y c r y s t a l d a t a f o r RBP, b u t from i t s s p e c t r a l and c h e m i c a l p r o p e r t i e s we sugges t ed t h a t t h e f l a v i n group must be l a r g e l y b u r i e d , in ana logy wi th t h e known s t r u c t u r e of f l a v o d o x i n . Because of i t s b u l k and a s s o c i a t e d charge , i t i s r e a s o n a b l e to a rgue t h a t t he formate r a d i c a l must r e a c t a t t h e s u r f a c e of t h e p r o t e i n . Hence , t h e f i r s t p r o d u c t o f t h e COg r e a c t i o n may no t be in c o v a l e n t con tac t wi th the f l a v i n group.

The second example i s t he r e d u c t i o n of RNase by CQg. This r a d i c a l can r e d u c e one o r more d i s u l f i d e s i n n a t i v e RNase v i a an o b s e r v e d i n t e r m e d i a t e r a d i c a l w i t h an a b s o r p t i o n maximum n e a r 370 nm. T h i s band , s i m i l a r t o t h e band o b s e r v e d f o r COg, s u g g e s t s t h a t t h e i n t e r m e d i a t e r a d i c a l i s an e l e c t r o n a d d u c t on a c a r b o n y l . As i n t h e RBP c a s e , t h e s u b s e q u e n t s l o w e r d i s u l f i d e r e d u c t i o n had b o t h f i r s t and s e c o n d o r d e r r e a c t i o n components. We proposed an i n t r a m o l e c u l a r e l e c t r o n m i g r a t i o n from the. s u r f a c e of the p r o t e i n t o t he d i s u l f i d e . REFERENCES: [1] F a r a g g i , M., S t e i n e r , J . and K l a p p e r , M. H., B i o c h e m i s t r y 2±, 3273

(1985) . [2] S t e i n e r , J . , F a r a g g i , M., K l a p p e r , M. H. a n d D o r f m a n , L. M.,

Biochemis t ry 24_, 2139 (1985) . [3 ] F a r a g g i , M., K l a p p e r , M. H. and Dorfman, L. M., J . P h y s . Chem. 8 2 , 508

(1978) . [4] F a r a g g i , M., K l a p p e r , M. H. and Dorfman, L. M., B i o p h y s . J . 24., 307

(1978) . [5] Klapper , M. H. and F a r a g g i , M., Quart . Rev. Biophys . J_2, 465 (1979) .

ONE ELECTRON REDUCTION OF RIBOFLAVIN BINDING PROTEIN IN CO, + [ 1 ]

M. Faragg i and M. H. Klapper We h a v e p r e v i o u s l y shown t h a t RBP, a m o d e l c o m p o u n d f o r

f l a v o p r o t e i n s , c o n t a i n s a d i s u l f i d e b r i d g e [ 2 ] . In t he r e d u c t i o n by CO^, RSSR'1 and the RBP-F1H were a l s o t he r e a c t i o n p roduc t s . However, t h e r e was no e v i d e n c e f o r t h e p r e s e n c e of u n p r o t o n a t e d semiquinone (RBP-Fl"). The r a t e of RSSR- format ion was one order of magnitude f a s t e r than t h e r a t e of RBP-F1H f o r m a t i o n . The y i e l d s of bo th s p e c i e s were e q u a l ( 4 0 $ ) . The d i s u l f i d e r a d i c a l decayed s l o w l y (9.7 s e c " ) s i m i l a r t o t h a t obse rved a f t e r e~ r e d u c t i o n . We t h e r e f o r e concluded t h a t no e l e c t r o n t r a n s f e r p roces s occur red between RSSR" and ox id i zed f l a v i n . REFERENCES:

[1] Fa ragg i , M. and Klapper , M. H., in F l a v i n s and F l a v o p r o t e i n s , e d i t e d by R. C. B r a y , P . C. E n g e l and S. G. Mayhew, De G r u y t e r , B e r l i n , 1984 , pp. 7 4 5 - 7 4 8 .

[2] Klapper , M. H. and F a r a g g i , M., Biochemis t ry 22 , 4067 (1983) .

Th i s work was performed a t Ohio S t a t e U n i v e r s i t y , Columbus, OH, U.S.A. Ohio S t a t e U n i v e r s i t y , Columbus, OH, U.S.A.

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ONE ELECTRON REDUCTION OF RIBOFLAVIN BINDING PROTEIN+[1] M. H. Klapper and M. Faraggi

The one e l ec t ron reduction of RBP by e~ over the time and spec t r a l r anges of 1 microsecond to 1 second, and 300 t o 600 nm, r e s p e c t i v e l y , was i n v e s t i g a t e d . The e~ to p r o t e i n c o n c e n t r a t i o n r a t i o was kept low to minimize double e l e c t r o n r e d u c t i o n of the RBP molecu le . The f i n a l and s t a b l e product of the o v e r a l l react ion i s RBP-FIH, the protonated f l a v i n semiquinone form of RBP. The minimal scheme sugges ted to e x p l a i n the react ion k ine t i c s was:

eRBP-XSSX~ • products

RBP-Fl~ ,^-RBP-FlH

The r e a c t i o n was monitored a t 350 nm ( i s o s b e s t i c po in t of the p ro tona t ed and the unpro tona ted semiquinones s e r v i n g to monitor the format ion of XSSX ) and 5^0 nm ( to monitor the decay of e , the anionic semiquinone and t h e p r o t o n a t e d s e m i q u i n o n e ) . F o r m a t i o n of R B P - F l r , t h e a n i o n i c semiquinone, was concurrent with the disappearance of e~ , and was seen as a pos i t i ve absorbance at 540 nm concomitant with the fast e~ decay. The protonation of RBP-Fl" to form RBP-FIH is then observed as an absorbance i n c r e a s e (k a p D = H.8x10^s~1 a t pH 9) . However, a second t r a n s i e n t , the o n e - e l e c t r o n reduced d i s u l f i d e (XSSX-) i s a l s o formed dur ing t h e e~

i n - 1 - 1 - a "

r e a c t i o n (k3r ,n = 1.4x10 luM ] s ' ) . The formation of XSSX a t 352 nm was concomitant with the decay of e_„. I t s decay, which was a slow p roces s (k_„_ = 9.7 s ), l ed us t o the c o n c l u s i o n t h a t no e l e c t r o n s were

aPP _ _ t ransferred from XSSX to the f l a v i n group. The y i e ld s of XSSX and RBP"-FlH were each 20-25% of the r e a c t e d e~ . S p e c t r a l a n a l y s i s of the t r a n s i e n t s formed supported the above mechanism. REFERENCE: [1] Klapper, M. H. and Faraggi, M., Biochemistry 22, H067 (1983).

OH RADICAL FORMATION BY PH0T01RRADIATI0N OF AQUEOUS PORPHYRIN S0LUTI0NS++ [1]

M. Faraggi, A. Carmichael and P. Riesz

Radica l p roduc t ion dur ing the p h o t o l y s i s of deae ra t ed aqueous a l k a l i n e s o l u t i o n s (pH 11) of some w a t e r - s o l u b l e po rphyr ins was i n v e s t i g a t e d . M e t a l - f r e e and m e t a l l o complexes of TMPyP and TPPS were studied. Evidence for the formation of OH r a d i c a l s during the photolys is

+This work was performed at Ohio State Universi ty, Columbus, OH, U.S.A. Ohio Sta te Universi ty, Columbus, OH, U.S.A. This work was performed at the National Cancer I n s t i t u t e , Bethesda, MD,

U.S.A. National Cancer I n s t i t u t e , Bethesda, MD, U.S.A.

123

at 615, 545, 435, 408, and 335 nm of Fe(III)TPPS was given. Fe(III)TMPyP, Mn(III)TPPS and Mn(III)TMPyP also gave OH radicals, but only when photolyzed at 335 nm. The method of spin-trapping with DMPO and POBN combined with esr was used for the detection of OH, H and e~ . With the

aq spin trap DMPO, photolysis generated DMP0-0H adducts under certain conditions, but no DMPO-H adducts could be observed. With the spin trap POBN, no POBN-H adducts were found. The formation of OH radicals was confirmed by studying competition reactions for OH radicals between the spin traps and OH radical scavengers (formate and isopropanol) and the concomitant formation of the CO^ and the (CHo)2C0H adduct with both DMPO and POBN. The photochemical generation of OH radicals was pH dependent; at pH 7.5 no OH radicals were detected. Photolysis (615~335 nm) of the dicyano complexes of the Fe(III) porphyrins did not produce OH radicals. When the corresponding Cu(II), Zn(II), Ni(II) and the metal-free porphyrins were photolyzed between 615 and 335 nm, no OH radicals could be spin trapped. These results tend to associate the well-known phenomenon of. photoreduction of Fe(III) and Mn(III) porphyrins with the formation of OH radicals. This process is described mainly as a photoreduction of the metal ion via an intramolecular electron transfer process from the hydroxyl axial ligand. REFERENCE: [1] Faraggi, M., Carmichael, A. and Riesz, P., Int. J. Radiat. Biol. 46,

703 (1984).

ONE ELECTRON REDUCTIOi, OF DAUNORUBICINE+ [1 ] o « %t y v

C. Houee-Levin , M. Gardes-Albert , C. Ferradini , M. H. Klapper and M. Faraggi

Daunorubicine i s an antitumoral a n t i b i o t i c used in the treatment of so l id tumors. This molecule (DOS) i s composed of anthraquinone (D) bound to an amino-sugar (S). The one e lec t ron reduction of DOS by e" and COp was studied. Following these react ions a t rans ien t absorbing species of the rad ica l D -OS characterized by i t s spectrum with bands centered at 380, 470 and h igher than 750 nm were observed . Second order r a t e c o n s t a n t s ( in M~1s"1) for e~ and CO^ were 1.7x1010 and 2.5x109 r e s p e c t i v e l y . The rad ica l produced disappears by a r a d i c a l - r a d i c a l dismutation reaction with a r a t e cons tan t of 2.6x10" and l e ads t o a p s e u d o - e q u i l i b r i u m dur ing a per iod of a t l e a s t 500 msec. The e q u i l i b r i u m i s s l o w l y des t royed by the loss of the sugar par t via a f i r s t order react ion (k = 0.3 s~1). REFERENCE: [1] Houee-Levin, C , Gardes -Albe r t , M., F e r r a d i n i , C , Klapper , M. H. and

Faraggi, M., FEBS Let t . 179, 46 (1985).

This work was performed at Ohio Sta te University, Columbus, OH, U.S.A. University of Par is (Rene Descartes), Pa r i s , France Ohio State University, Columbus, OH, U.S.A.

124

ION CHEMISTRY OF CYANIDES AND ISOCYANIDES. 1. THE CARBON LONE PAIR AS PROTON ACCEPTOR: PROTON AFFINITIES OF ISOCYANIDES* [ 1 ] M. Meot-Ner (Mautner) , Z. Karpas and C. A. Deakyne

The p r o t o n a f f i n i t i e s (PAs) of i s o c y a n i d e s RNC, R = CH,, C 2H 5 , i -C^H-, t-CjjHg and CgHg r a n g e from 199 t o 207 k c a l / m o l . The PAs o f a l l i s o c y a n i d e s a r e h igher than t h o s e of the co r re spond ing c y a n i d e s , RCN, by a c o n s t a n t 11.5 ± 1 k c a l / m o l r e g a r d l e s s o f t h e i d e n t i t y of R. The i s o m e r i z a t i o n e n e r g i e s of t h e RNCH+ ions to RCNH+ a r e 5 ~ 11 k c a l / m o l , and a r e s m a l l e r by 11 - 15 k c a l / m o l t h a n t h e i s o m e r i z a t i o n e n e r g i e s o f t h e r e s p e c t i v e n e u t r a l cyan ides . The bond d i s s o c i a t i o n e n e r g i e s D° (R+-NCH) as o b t a i n e d from t h e d a t a , a s w e l l a s D° f o r R+-CNH, R + -0H 2 and R+-NHq ; ,iow u n e x p e c t e d l y good l i n e a r c o r r e l a t i o n s wi th t h e s t a b i l i t i e s of the R ions a s m e a s u r e d by t h e h y d r i d e a f f i n i t y , i . e . , D ° ( R + - H ~ ) . Ab i n i t i o c a l c u l a t i o n s were u s e d t o a n a l y z e t h e t r e n d s i n p r o t o n a f f i n i t i e s . The r e s u l t s show t h a t the main s t r u c t u r a l e f f e c t s of p r o t o n a t i o n on the carbon lone p a i r of CH NC a r e t he s h o r t e n i n g of the N-C and the l e n g t h e n i n g of the H-,C-N bonds. The c a l c u l a t i o n s a l s o sugges t t h a t the i n c r e a s e d PAs of RNC v s . RCN a r i s e p r i m a r i l y f rom t h e i n c r e a s e d c h a r g e t r a n s f e r and e l e c t r o s t a t i c pro ton - m u l t i p o l e i n t e r a c t i o n s in the i s o c y a n i d e s . However, t he p a r a l l e l i n c r e a s e of t he PAs of both RCN and RNC wi th i n c r e a s i n g s i z e o f R i s d u e p r i m a r i l y t o t h e i n c r e a s i n g p o l a r i z a b i 1 i t i e s o f t h e s u b s t i t u e n t s . REFERENCE:

[1 ] Meo t -Ne r ( M a u t n e r ) , M., K a r p a s , Z. and Deakyne, C. A., J . Am. Chem. S o c , i n p r e s s .

ION CHEMISTRY OF CYANIDES AND ISOCYANIDES. 2. ALKYLATION OF HCN AND CYANIDES BY OXYGEN AND SULFUR COMPOUNDS. GAS-PHASE SYNTHESIS AND REACTIONS OF PROTONATED ISOCYANIDES+ [ 1 ]

M. Meot^Ner (Mautner) and Z. Karpas The r e a c t i o n : R0H2

+ + HCN > RNCH+ + H20 was obse rved in mix tures c o n t a i n i n g a l c o h o l s and HCN. Pro ton a f f i n i t y b r a c k e t i n g exper iments showed t h a t the p roduc ts a re p ro tona t ed i s o c y a n i d e s , RNCH , which a r e formed by a l k y l a t i o n of the n i t r o g e n in HCN, r a t h e r than p ro tona t ed cyan ides , RCNH . A l t h o u g h t h e l a t t e r a r e more s t a b l e , t h e i r p r o d u c t i o n would r e q u i r e rea r rangement . S i m i l a r r e a c t i o n s were obse rved between (CHg)20H and RSH2

and HCN. CH^CN and HC^N (cyanoace ty l ene ) can a l s o be a l k y l a t e d in s i m i l a r fash ion to form the n i t r i l i u m ions CHoCNCH, and HCoNCH, , r e s p e c t i v e l y . In c a s e s where t he p r o t o n a f ^ ' ^ i t y of t h e n i t r i l e i s h i g h e r t h a n t h a t of t h e a l c o h o l , a l k y l a t i o n o-; "< - by a c o n d e n s a t i o n r e a c t i o n , such a s in

T h i s work was p e r f o r m e d a t t h e N a t i o n a l B u r e a u o f S t a n d a r d s , G a i t h e r s b u r g , MD, U.S.A. Na t iona l Bureau of S t a n d a r d s , G a i t h e r s b u r g , MD, U.S.A. Air Force Geophysics Labora to ry , Hanscom AFB, Bedford, MA, U.S.A.

125

methanol and acetonitrile: CH3CNH+ + CH^OH > CH3NCCH3

+ + H20. The rate

constants for the alkylation reactions are generally in the range of (1 -

10)x10-11 cm3 sec"1 and are not affected significantly by the reaction

exothermicity or by the structure of the reactants. These reactions may

contribute to the synthesis of isocyanides in interstellar clouds and

planetary atmospheres.

REFERENCE:

[1 ] Meot-Ner (Mautner) , M. and Karpas , Z . , J . Phys . Chem., in p r e s s .

ON THE MECHANISM OF FORMATION OF DIALKYLHALONIUM IONS IN ALKYL HALIDES+

Z. Karpas and S. G. L i a s

The mechanisms of t h e r e a c t i o n s :

RX+ + RX > RXR+ + X

and

RXH+ + RX > RXR+ + HX

where R = CH^ or C2H5 and X = CI or Br, were e l u c i d a t e d by i o n c y c l o t r o n

r e s o n a n c e d o u b l e r e s o n a n c e t e c h n i q u e s , u s i n g t h e n a t u r a l l y - o c c u r r i n g ha logen i s o t o p e s as l a b e l s t o s o r t ou t the r e a c t i o n mechanism. The CH,C1H and CHoBr i o n s r e a c t wi th the r e s p e c t i v e pa ren t methyl h a l i d e m o l e c u l e s t o form d i m e t h y l h a l o n i u m p r o d u c t i o n s t h r o u g h an S^2 mechanism i n v o l v i n g approach from the back s i d e r e l a t i v e to the X or HX l e a v i n g group, i . e . t h e r e a c t i o n s a r e methyl ion t r a n s f e r s . In the cor responding r e a c t i o n s in t h e e t h y l h a l i d e systems, e t h y l ion t r a n s f e r mechanisms a r e impor t an t , bu t in e v e r y c a s e t h e r e i s a s i g n i f i c a n t c o n t r i b u t i o n from a s e c o n d mechanism, e i t h e r complex format ion ( i . e . ha logen atoms s t a t i s t i c a l l y d i s t r i b u t e d in t h e p r o d u c t s ) or a l k y l t r a n s f e r from t h e n e u t r a l t o t h e i o n ( t h e h a l o g e n atom in t h e product ion o r i g i n a t i n g from the r e a c t a n t ion) .

PROTON AFFINITY AND GAS-PHASE ION CHEMISTRY OF METHYL ISOCYANATE, METHYL ISOTHIOCYANATE, AND METHYL THIOCYANATE+ [ 1 ]

Z. Karpas, W. J . S tevens , T . J . Buckley and R. Metz The g a s - p h a s e ion c h e m i s t r y of CH^NCO, CHoNCS and CHgSCN was

i n v e s t i g a t e d by p u l s e d ICR t e c h n i q u e s and t h e i r p r o t o n a f f i n i t i e s were d e t e r m i n e d a s b e i n g 181.5 + 0 . 5 , 193-0 + 0.H and 192.6 + 0.5 k c a l / m o l , r e s p e c t i v e l y . The main r e a c t i o n of t h e m o l e c u l a r i o n i n t h e t h r e e compounds i s p roduc t ion of the p r o t o n a t e d mo lecu l e . The C^X* i o n s , where X = NCO, NCS, or SCN, a r e u n r e a c t i v e toward t h e p a r e n t m o l e c u l e . The fragment ions CHnY

+, where n = 0~3 and Y = 0 or S, r e a c t by charge t r a n s f e r

+ T h i s work was performed a t the N a t i o n a l Bureau of S t a n d a r d s , Ga i the r sbu rg , MD, U.S.A. N a t i o n a l Bureau of S t a n d a r d s , G a i t h e r s b u r g , MD, U.S.A.

126

or proton t r a n s f e r . The p r o t o n a t e d m o l e c u l e s r e a c t ve ry s l o w l y w i t h t h e i r p a r e n t compounds. A l t h o u g h p r o t o n a t e d d i m e r s were o b s e r v e d t h e i r p roduc t ion i s i n e f f i c i e n t . Ab i n i t i o c a l c u l a t i o n s a t the SCF l e v e l were used t o de te rmine t he s t r u c t u r e s of the n e u t r a l and p r o t o n a t e d m o l e c u l e s . The c a l c u l a t e d p r o t o n a f f i n i t i e s , 188 .5 , 188.6 and 193.7 k c a l / m o l f o r CHoNCO, CH^SCN and CHoNCS, r e s p e c t i v e l y , a r e i n good a g r e e m e n t w i t h t h e expe r imen ta l v a l u e s . The favored s i t e of p r o t o n a t i o n was found t o be the n i t r o g e n a tom i n t h e f o r m e r two, w h i l e i n CH^NCS t h e s u l f u r a tom i s t h e p r e f e r r e d s i t e of p r o t o n a t i o n . REFERENCE:

[ l ] K a r p a s , Z . , S t e v e n s , W. J . , B u c k l e y , T. J . and Meta , R., J. P h y s . Chem.

89 , 527^ (1985)

THE PBOTON AFFINITY OF HgSe, SeCO AND H2CSe AND REACTIONS OF POSITIVE IONS

WITH H2Se+ [ 1 ]

Z . Karpas The p r o t o n a f f i n i t i e s of SeCO and H2CSe were d e t e r m i n e d by p u l s e d

ICR t e c h n i q u e s and found t o be 157 £ 3 and 186 + 1 k c a l / m o l , r e s p e c t i v e l y . The p r o t o n a f f i n i t y of H2Se and of H2CS were found t o be 171.2 + 0.2 and 181!-7 ± 1 . 0 k c a l / m o l , r e s p e c t i v e l y , i n a g r e e m e n t w i t h e a r l i e r d e t e r m i n a t i o n s . The gas -phase ion chemis t ry of H2Se g r e a t l y r e s e m b l e s t h a t of H2S. REFERENCE: [1] Karpas, Z . , Chem. Phys . L e t t . 1 2 0 , 53 (1985) .

THE PROTON AFFINITY OF HYDROGEN TELLURIDE [ 1 ]

Z . Karpas and P . G. J a s i e n The pro ton a f f i n i t y of hydrogen t e l l u r i d e , H2Te, was de termined by

p u l s e d ICR t e c h n i q u e s a s be ing 175.8 + 0.1 k c a l / m o l . This v a l u e i s in good agreement wi th ab i n i t i o c a l c u l a t i o n s which were performed a t t he SCF and c o r r e l a t e d l e v e l s . This t r e n d observed in t h e hydrogen c h a l c o g e n i d e s , t h a t the pro ton a f f i n i t i e s i n c r e a s e as one moves down Group VIA of t he p e r i o d i c t a b l e , ex tends a l s o to t e l l u r i u m . REFERENCE:

[1 ] K a r p a s , Z. and J a s i e n , P. G., I n t . J . Mass S p e c t r o m . Ion P r o c . 6j), 115 (1986) .

GRAFTING OF ACRYLAMIDE TO NYL0NH6 BY THE ELECTRON BEAM PREIRRADIATION TECHNIQUE. V. PERMEABILITY AND SELECTIVITY OF THE GRAFTED MEMBRANES Y. Haruvy, L. A. Rajbenbach and J . J agur^Grodz insk i

N y l o n s g r a f t e d a c r y l a m i d e (NYgAM) membranes were m o d i f i e d by

+ T h i s work was p e r f o r m e d a t t h e N a t i o n a l B u r e a u o f S t a n d a r d s , G a i t h e r s b u r g , MD, U.S.A. Na t iona l Bureau of S t a n d a r d s , G a i t h e r s b u r g , MD, U.S.A. Weizmann I n s t i t u t e of S c i e n c e , Rehovot

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cross l ink ing and/or annealing with 65$ aqueous so lu t ion of formic acid a t room tempera ture . The p e r m s e l e c t i v i t y p r o p e r t i e s of the t r e a t e d NYgAM membranes to a number of ionic so lu te s of varying molecular s ize ranging from HBr to tetrabutylammonium-bromide (Bu^NBr) were s t u d i e d in the temperature range of 27-1t7°C. The temperature dependence of the permeation constants through the cross linked membranes indicates an apparent energy of ac t iva t ion of 6.6 and 11.3 kcal/mole for HBr and Bu^Br, r e spec t ive ly . In the crosslinked and annealed membranes the corresponding ac t iva t ion energy v a l u e s were found to range from H.H t o 5.6 k c a l / m o l e , r e f l e c t i n g the inc reased water uptake of the annealed membranes. The f l u x of water and sma l l s o l u t e s through the 135 pm t h i c k c r o s s l i n k e d and annea led NYgAM membranes was found to be approximate ly equal to t h a t of 18 urn t h i ck c e l l o p h a n e f i l m s . The p e r m e a b i l i t y c o e f f i c i e n t s of urea , u r i c ac id , raffinose and inu l in through the crossl inked annealed NYgAM membranes were determined in o rder to e s t a b l i s h the p o t e n t i a l a p p l i c a b i l i t y of the modified membranes to the separation of metabol i tes . The flux of a l l four so lu t e s , e spec i a l l y tha t of ur ic acid, through the modified NYgAM membranes was found to be h ighe r than through the c e l l o p h a n e f i l m s , i n d i c a t i n g po ten t ia l appl ica t ion for hemodialysis.

MECHANISTIC FEATURES OF GAMMA RADIATION-INDUCED FORMATION OF Pt HYDROSOLS Y. Haruvy and L. A. Rajbenbach

In a p r e v i o u s study we have shown [1] t h a t gamma i r r a d i a t i o n of aqueous s o l u t i o n s of HgPtClg and N-methy lo lac ry lamide l e a d s to the formation of Pt(0) c o l l o i d a l dispersions of high s t a b i l i t y . In the present inves t iga t ion e f for t s were made to es tab l i sh the mechanistic features of t h e P t ( IV) -P t (0 ) r e d u c t i o n c y c l e . The n o t a b l e f e a t u r e s , most l i k e l y involved in the gamma radiation-induced formation of Pt hydrosols, can be summarized as fo l lows: a) In the ear ly stages of r ad io ly s i s , e l ec t rons which escaped react ion with

NMAM and monomer de r ived r a d i c a l s reduce Pt(IV) to P t ( I I I ) . The reaction of NMAM r a d i c a l species with Pt(IV) proceeds via the formation of a Pt(IV)/NMAM r a d i c a l complex. The l a t t e r s p e c i e s r e v e r t s to a P t ( I I I ) s t a t e by in te rna l e lect ron t ransfer and quite l i k e l y may a l so engage in a r e a c t i o n with the monomer, i n i t i a t i n g a p o l y m e r i z a t i o n p rocess . Upon d e p l e t i o n of Pt(IV) ions the p o l y m e r i z a t i o n p rocess i s i n i t i a t e d by NMAM rad ica l reaction with the monomer.

b) P t ( I I ) formed by disproportionation of P t ( H I ) species is s t a b i l i z e d by NMAM and accumulates in the system u n t i l the concentration of NMAM is depleted by polymerization below that of P t ( I I ) .

c) The formation of me t a l l i c Pt r e s u l t s mainly from a dark react ion between P t ( I I ) and the polymeric alcohol-(PNMAM). The l a t t e r r e a c t i o n i s catalyzed by Pt(0). The thermal reduction of Pt(II) to Pt(0), which i s i n h i b i t e d by the presence of o l e f i n s , has been a l s o observed by us to occur in aqueous s o l u t i o n s of MeOH and of i sop ropano l . However, the time sca le of these reduction processes was higher by severa l orders of

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magnitude than t h a t o c c u r r i n g in the p resence of PNMAM. The occur rence of a dark r e a c t i o n between P t ( I I ) and PNMAM which i s suppres sed by t h e p r e s e n c e of f r e e NMAM a c c o u n t s f o r t h e o b s e r v a t i o n t h a t m e t a l l i c P t format ion becomes n o t i c e a b l e o n l y a f t e r a c r i t i c a l dose of r a d i a t i o n has been d e l i v e r e d to t h e system t o d e p l e t e NMAM c o n c e n t r a t i o n below t h a t of P t ( I I ) .

REFERENCE: [1 ] R a f a e l o f f , R., H a r u v y , Y., B i n e n b o y m , J . , B a r u c h , G. a n d

R a j b e n b a c h , L. A., J . Mol . C a t a l . 22 , 219 (1983).

THE EFFECT OF ADSORPTION ON THE GAS PERMEABILITY THROUGH THE CARBON MOLECULAR SIEVE MEMBRANE

J . E. Koresh and A. Sof fe r The membrane p r o c e s s f o r g a s m i x t u r e s e p a r a t i o n i s nowadays based

m a i n l y on g l a s s y po lymer membranes . D e s p i t e t h e i r r e c e n t i n d u s t r i a l u t i l i z a t i o n , they have some l i m i t a t i o n s as t o h igh t empera tu re s t a b i l i t y , p l a s t i c i z i n g e f f e c t s in p r e s e n c e of C02 and o r g a n i c v a p o r s , and low s e l e c t i v i t y f o r Op-N_ s e p a r a t i o n . R e c e n t l y t h e c a r b o n m o l e c u l a r s i © v e membrane (MSCM) was i n t r o d u c e d i n t h e a d v a n t a g e o u s h o l l o w f i & s r c o n f i g u r a t i o n [ 1 ] . I t e x h i b i t e d a d i s t i n c t i v e s e l e c t i v i t y fo r 0 2 i n f avor o f N2 . I t i s o p e r a t i v e a t t e m p e r a t u r e s a s h i g h a s 700°C and e x h i b i t s a s e p a r a t i o n power which i s 1 t o 3 o r d e r s of m a g n i t u d e g r e a t e r t h a n t h a t of any known po lymer ic membrane.

In the p r e s e n t s tudy a comparison between the permeat ion mechanism of g l a s s y p o l y m e r s and t h e MSCM was made. I t was s u g g e s t e d t h a t u n l i k e polymer membranes, permeat ion through the MSCM proceeds e x c l u s i v e l y through t h e u l t r a m i c r o p o r e s w i t h no c o n t r i b u t i o n from t h e s o l u t i o n - d e s o l u t i o n mechanism. On t h e b a s i s of a d s o r p t i o n i s o t h e r m s and p e r m e a b i l i t y , t h e r e l a t i o n be tween a d s o r p t i o n and p e r m e a t i o n i s e s t a b l i s h e d . I t was s u g g e s t e d t h a t c l e a r d i s c r i m i n a t i o n b e t w e e n s u r f a c e and b u l k d i f f u s i o n mechanisms i s inadequa te fo r pores of m o l e c u l a r dimensions . The r e l a t i o n be tween p e r m e a b i l i t y of a g a s m i x t u r e and t h a t of p u r e componen t s was cons ide red on the b a s i s of pore morphology and a d s o r p t i o n . REFERENCE: [1 ] Koresh, J . E. and S o f f e r , A. , S e p a r a t i o n S c i . Technol . JJ3, 723 (1983) .

SYNTHESIS OF FLUORINATED IONOMER MEMBRANES BY THE ELECTRON BEAM PREIRRADIATION METHOD

A, Mey^-Marom and S. Shkolnik Perf luor ina ted ionomer mater ia l s are used to produce cation exchange

membranes with high thermal s t a b i l i t y and very good re s i s t ance to r eac t i ve chemical agents. These membranes are used in novel i n d u s t r i a l c h l o r - a l k a l i e l e c t r o l y s i s processes for manufacturing chlor ine and sodium hydroxide, two of the l a rge s t tonnage chemicals produced in the world [1 ] , Perf luor inated ionomer membranes a re very expens ive and therefore a l t e r n a t i v e , cheaper

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membranes a r e s o u g h t [ 2 , 3 ] . A p r o m i s i n g a p p r o a c h t o o b t a i n i n g l e s s expens ive membranes i s t o modify commercial f l u o r i n a t e d f i l m s by g r a f t i n g ca rboxy l and /or s u l f o n y l c o n t a i n i n g s p e c i e s .

A long- te rm p r o j e c t t o s y n t h e s i z e f l u o r i n a t e d ionomer membranes by e l e c t r o n beam p r e i r r a d i a t i o n g r a f t i n g was begun. The mechanica l s t r e n g t h of Tef lon ( p o l y t e t r a f l u o r o e t h y l e n e - P T F E ) f i l m was s t u d i e d a s a func t ion of i r r a d i a t i o n dose and s t o r a g e t i m e . I t was found t h a t a dose of 0.3 Mrad may be a p p l i e d to the f i lm and ye t r e t a i n t e n s i l e p r o p e r t i e s high enough t o permit h a n d l i n g and use of the g r a f t e d f i lm.

PTFE f i l m was g r a f t e d w i t h a c r y l i c a c i d (AAc) unde r d i f f e r e n t expe r imen ta l c o n d i t i o n s . P r e p a r a t i o n of such membranes has been r e p o r t e d in t h e l i t e r a t u r e [ 4 ] , b u t o n l y low a d d - o n p e r c e n t a g e s (up t o \0%) were o b t a i n e d . I n t h i s work t h e c o n d i t i o n s of t h e g r a f t i n g p r o c e s s were m o d i f i e d i n o r d e r t o a c h i e v e h i g h e r a d d - o n , and membranes w i t h up t o 5H% AAc were obta ined. A p r e l i m i n a r y e v a l u a t i o n of the membranes showed t h a t an i n c r e a s e of AAc add-on from 25? to 54% p r o v i d e s an i n c r e a s e of water u p t a k e ( i n t h e K - s a l t form) from 54? t o 253$ . Thus , b e t t e r p e r f o r m a n c e o f the h igh add-on membranes in e l e c t r o l y s i s c e l l s may be expected .

Graf t ing of o the r f l u o r i n a t e d f i l m s wi th d i f f e r e n t c a r b o x y l a t e d or s u l f o n a t e d monomers i s under way. REFERENCES: [1 ] E i s e n b e r g , A. and Yeager , H. L., e d i t o r s , P e r f l u o r i n a t e d Ionomer

Membranes, ACS Symposium S e r i e s No. 180, ACS, W a s h i n g t o n , D.C., 1982,

p . 5 . [2] I b i d , p. 469. [3] Yeo, R. S . , Chan, S. F. and Lee, J . , J . Membr. S c i . 9, 273 (1981) . [4] Mas, L., B e r n a r d , M., C h a p i r o , A. and Bonamour, A. M., Fr . Dera.

No. 2 , ^ 9 ^ , 7 0 2 , 1980.

OMIDERM, A NEW SYNTHETIC WOUND COVERING: DRUG PERMEABILITY STUDIES * fc #

D. Behar, M. Juszynski, J . Golan , B. Rudensky and N. Ben Hur Omiderm (Omikron Sc ien t i f i c Ltd., Rehovot, I s r a e l ) , a new synthet ic

wound covering based on hydrophilized polyurethane, was found to be highly permeable to water. Values in the region of 5000 g/m2 24h were found for the water p e r m e a b i l i t y of Omiderm in comparison to 1400 and 500 g/m2 24h for Biobrane ( H a l l , Woodroof Inc . , Santa Ana, CA) and Op s i t e (Smith and Nephew Ltd.), r espec t ive ly . Permeabi l i t ies of a n t i b a c t e r i a l agents through Omiderm were found to be two to t h r e e o rders of magnitude g r e a t e r than those through Biobrane.

The in v i t r o e f f e c t i v e n e s s of v a r i o u s a n t i b a c t e r i a l agen t s in lowering bac t e r i a l growth of different bac t e r i a l s t r a i n s when applied to seeded agar p la tes through Omiderm membrane was invest igated. NBH ointment (1% Neomycin, \% B a c i t r a c i n and 0.5? Hydrocor t i sone) was found to be the

Shaare Zedek Medical Center, Jerusalem

1 30

most e f f e c t i v e m a t e r i a l in i n h i b i t i n g b a c t e r i a l growth, except for Pseudomonas aerugenosa where s i l v e r sul fadiazine was superior.

In in vivo experiments b a c t e r i a l counts of infected wounds covered with Omiderm and t o p i c a l l y t r e a t e d with NBH were lowered to l e s s than 10^ organisms/g t i s sue af ter one day of treatment. Omiderm alone was able to decrease the b a c t e r i a l counts of infected wounds by frequent changing of the membrane without the use of any a n t i b a c t e r i a l agents.

ON THE ALKYLATION OF OXYGEN COMPOUNDS'1"

Z. Karpas and M. Meot^Ner (Mautner) Alkylat ion reac t ions at the oxygen s i t e of saturated and unsaturated

systems were s t u d i e d . On t h e whole , t he se r e a c t i o n s proceed a t a s m a l l -fraction of the c o l l i s i o n frequency. As a lky l a t i on leads to formation of ions with longer carbon atom chains, i t can cons t i t u t e an important pathway to the production of complex species in i n t e r s t e l l a r clouds and planetary atmospheres.

ON THE KINETICS AND THERMODYNAMICS OF CYCLOALKANES+

S.G. L ias and Z. Karpas The r a t e s of r e a c t i o n of CH5

+ , C-H,- and C^Hc wi th c y c l o a l k a n e s CnH2n ^n = 3~8) were measured by t rapped ICR t echn iques . The proton a f f i n i t i e s of these cycloalkanes were determined and the s t ruc ture of some of the protonated molecules was deduced through k ine t ic and thermodynamic experiments.

POLYCYCLIC AROMATIC HYDROCARBONS (PAH) FROM COAL PYROLYSIS: MUTAGENIC EFFECTS £ £ tt# -X-&

A. Mitra , G. Braun , F. Sarofim and E. Bar-Ziv Pyrolys is of coal a t wel l defined laminar flow in the temperature

range of 900-1700K was s t u d i e d in order to de f ine a c o r r e l a t i o n between e v o l v e d PAH and mu tagen i c i t y . A v a r i e t y of c o a l s ranging from low rank l i g n i t e to a n t h r a c i t e were t e s t e d . I t was found t h a t t he s p e c i f i c mutagen ic i ty f o l l o w s a d i s t i n c t t r e n d : high v o l a t i l e - A bi tuminous >> l i g n i t e > subbi tuminous > a n t h r a c i t e . Also the PAH wi th high s p e c i f i c mutagenicity peak in the temperature range of 13OO-150OK.

HALOMETHYLENES: EFFECTS OF HALOGEN SUBSTITUTION ON ABSOLUTE HEATS OF FORMATION"*" [1] S. G. Lias , Z. Karpas and J . F. Liebman

New v a l u e s for the h e a t s of formation of CF2, CC12 , CC1F, CFH and CC1H were d e r i v e d from e s t i m a t i o n s of the thermochemistry of the

+ T h i s work was p e r f o r m e d a t t h e N a t i o n a l Bureau of S t a n d a r d s , Ga i the r sburg , MD, U.S.A. National Bureau of Standards, Gaithersburg, MD U.S.A. Massachusetts I n s t i t u t e of Technology, Cambridge, MA, U.S.A. University of Maryland, Baltimore County, MD, U.S.A.

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r e a c t i o n ( s ) CXYH+ + B —> CXY + BH+ where X and Y a re F and/or CI and B i s a molecule for which an absolute value of the gas-phase bas ic i ty (or proton a f f in i ty) i s a v a i l a b l e . The experiments, carr ied out in an ion cyclotron resonance spec t rome te r , l ead to the f o l l o w i n g v a l u e s for the h e a t s of formation (in kcal/mol) of the ground-state s i n g l e t carbenes: CF2, -1)9 ± 3; CC12 , 39 + 3; CFC1, -2 + 7; CFH, 26 t 3; CC1H, 71 t 5. The v a l u e for CF2

i s lower by about 5 k c a l / m o l than the p r e v i o u s l y accepted v a l u e , but in good agreement with values derived from previous "bracketing" r e s u l t s and a l so in agreement with values derived from the observed threshold energies for ionic d issoc ia t ion processes. The value for CC12 i s s i gn i f i can t ly lower than the 1976 value of hi + 3 kcal/mol recommended by S. W. Benson, but in good agreement with an e a r l i e r value (^0 i 5 kcal/mol) recommended by th i s author and with more recent experimental r e s u l t s on the onset energy for the formation of C l 2 " from CClj,. The values for CFH, CC1H and CFC1 are a l l approx imate ly equa l to the ave rages of the h e a t s of format ion of the cor responding CX2 and CY2 s p e c i e s , in agreement wi th assumpt ions made in previous estimates of these quan t i t i e s . Values for the C-X bond energies in the h a l o m e t h y l e n e s , t he h e a t s of formation of the cor responding CXY ions, and the ionizat ion p o t e n t i a l s of the CXY species are derived from the r e s u l t s . From the most r e c e n t c a l c u l a t i o n s of the energy d i f f e r e n c e s between the g r o u n d - s t a t e s i n g l e t h a l o m e t h y l e n e s and the f i r s t t r i p l e t s t a t e , values for the heats of formation of the t r i p l e t halomethylenes were ob t a ined ; an a n a l y s i s of t r e n d s in t he se v a l u e s i n d i c a t e s t h a t 3cF2 i s s u b s t a n t i a l l y des tab i l i zed . REFERENCE:

[1] L i a s , S. G., Karpas, Z. and Liebman, J . F., J . Am. Chem. Soc. 1 07, 6089 (1985).

THE INFLUENCE OF COAL TYPE ON THE EVOLUTION OF POLYCYCLIC AROMATIC HYDROCARBONS (PAH) DURING COAL DEVOLATILIZATION A. Mitra , A. F. Sarofim and E. Bar-Ziv

In t h i s study we presented data showing the dependence of the types and quan t i t i e s of PAH evolved during pyro lys is of coal on the aromatic nature of coal . A var ie ty of coals ranging from low-rank l i g n i t e to an thrac i te were pyrolyzed at wel l con t ro l l ed laminar conditions in the temperature range of 900-1700K. From GC-MS analysis i t was concluded that PAH chemical type from different coals is similar. The concentration of PAH and soot formed shows, however, a d i s t i n c t trend: high v o l a t i l e bituminous > medium v o l a t i l e > bituminous > subbituminous > l i g n i t e > anthracite.

Massachusetts Institute of Technology, Cambridge, MA, U.S.A.

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PURIFICATION OF AQUEOUS SUSPENSIONS FROM COLLOIDAL PARTICLES BY ELECTROADSORPTION ON POROUS CARBON ELECTRODES*

A. Sof fe r and Y. Oren C o l l o i d a l p a r t i c l e s in suspens ion c a r r y s u r f a c e charge and t h u s can

be c o n s i d e r e d a s e l e c t r o a c t i v e s p e c i e s . Depend ing on t h e pH, t h e i o n i c s t r e n g t h of t h e s o l u t i o n , t h e t y p e o f p a r t i c l e and t h e c h a r g e on t h e e l e c t r o d e , t h e c o l l o i d a l p a r t i c l e s can i n t e r a c t w i th an e l e c t r o d e a c c o r d i n g to the r e l a t i v e weight of the London-Van der Waals and the e l e c t r o s t a t i c f o r c e s . The e l e c t r o a d s o r p t i o n p r o c e s s i s impor tan t for the f i l t r a t i o n of very f i n e p a r t i c l e s s i n c e i t a l l o w s p a s s i n g the suspens ion through pores much l a r g e r t han the p a r t i c l e s .

P o l y s t y r e n e l a t e x p a r t i c l e s c a r r y i n g c a r b o x y l i c s u r f a c e groups were suspended in 1 0 ~ ^ M NaCl s o l u t i o n and passed through an e l e c t r o c h e m i c a l f low c e l l . V e r y l i t t l e a d s o r p t i o n - d e s o r p t i o n e f f e c t was o b s e r v e d upon a l t e r n a t i n g t he e l e c t r o d e p o t e n t i a l w i t h i n the double l a y e r range . Upon ex tend ing the p o t e n t i a l s t o the range where water decomposi t ion t a k e s p a r t , pH changes occur and induce p a r t i c l e a d s o r p t i o n or d e s o r p t i o n . At p o s i t i v e p o t e n t i a l s , pH i s low and the c o l l o i d s u r f a c e groups a r e not d i s s o c i a t e d . S t r o n g a d s o r p t i o n o c c u r s a s a r e s u l t of a t t r a c t i v e London-Van d e r Waa l s i n t e r a c t i o n s be tween t h e p a r t i c l e s and t h e e l e c t r o d e . At n e g a t i v e p o t e n t i a l s pH i s h i g h , t h e c a r b o x y l i c g r o u p s a r e d i s s o c i a t e d and t h e p a r t i c l e s a r e desorbed due to s t r o n g e l e c t r o s t a t i c r e p u l s i o n s .

S i n c e t h e s u r f a c e c h a r g e of many of t h e common c o l l o i d s i s pH dependent , t h i s p rocess i s impor tan t in c o l l o i d f i l t r a t i o n , due t o t he f a c t t h a t pH changes can be l o c a l i z e d near t h e e l e c t r o d e , t h u s a v o i d i n g changes in the pH of t he e n t i r e su spens ion .

ELECTRODEPOSITION OF RUTHENIUM FROM A LiCl<-KCl MELT [ 1 ]

A. B e t t e l h e i m , F . Broi tman, U. Mor and R. Har th

E l e c t r o p l a t i n g from m o l t e n s a l t s seems t o be a p r o m i s i n g way of s u r f a c e f i n i s h i n g , b o t h w i t h r e s p e c t t o p r o t e c t i o n a g a i n s t c o r r o s i o n and h i g h t e m p e r a t u r e o x i d a t i o n a s w e l l a s t h e p o s s i b i l i t y of o b t a i n i n g v e r y hard s u r f a c e s wi th s p e c i a l mechanica l p r o p e r t i e s . The p l a t i n u m group of m e t a l s can be d e p o s i t e d i n a q u e o u s e l e c t r o l y t e s [ 2 ] o n l y i n l i m i t e d t h i c k n e s s (<5 wn). I t has been r e p o r t e d t h a t LiCl-KCl e u t e c t i c m e l t s g i v e d e p o s i t s which a r e a l w a y s d e n t r i t i c and n o n a d h e r e n t [ 3 ] w h i l e g r e a t e r s u c c e s s i s o b t a i n e d i n m o l t e n c y a n i d e s y s t e m s . In t h e p r e s e n t s t u d y , we showed t h a t t h i c k , a d h e r e n t and compact e l e c t r o d e p o s i t s of ru thenium ( a t 11 wn) a r e o b t a i n e d from a LiCl-KCl (15_55 wt%) m e l t a t t e m p e r a t u r e s a s low as 100°C p rov ided t h a t the m e l t i s s a t u r a t e d wi th HC1.

i n c o l l a b o r a t i o n wi th D. H a l l and Z. P r i e l , Ben-Gurion U n i v e r s i t y of the Negev, Beer -Sheva .

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REFERENCES: [ 1 ] B e t t e l h e i m , A., B r o i t m a n , F . , Mor, U. and H a r t h , R., J . E l e c t r o c h e m .

Soc . 1 3 2 , 1775 ( 1 9 8 5 ) . [ 2 ] Hydes, P . C., P la t inum Met. Rev. 24 , 50 (1980) . C3] Not ton , J . H. F . , P la t inum Met. Rev. 2 2 , 98 (1978) .

ELECTROADSORPTION OF COLLOIDS ON ELECTRODES Y. Oren

The e l e c t r i c a l l y induced a d s o r p t i o n of suspended c o l l o i d a l p a r t i c l e s on c h a r g e d e l e c t r o d e s was s t u d i e d by v i r t u e of t h e HHF-Hamaker t h e o r y . S u r f a c e p o t e n t i a l s were c a l c u l a t e d by t h e Gouy-Chapman model f o r t h e d i f f u s e double l a y e r . P a r t i c l e - p a r t i c l e and p a r t i c l e - s u r f a c e i n t e r a c t i o n s were compared fo r s e v e r a l c a s e s of s u r f a c e - t o - p a r t i c l e c h a r g e d e n s i t y r a t i o s .

REMOVAL OF MERCURY FROM AQUEOUS SOLUTIONS BY ELECTRODEPOSITION ON FIBROUS CARBON ELECTRODES Y. Oren, M. Abda and A. Sof fe r

Mercury p r e s e n t s an e n v i r o n m e n t a l problem, p a r t i c u l a r l y in a r e a s ne ighbor ing c h l o r - a l k a l i p l a n t s and paper m i l l s . Due t o i t s h igh t o x i c i t y , the c o n c e n t r a t i o n of mercury in water r e s o u r c e s has t o be reduced to below t h e 2 ppb l e v e l s . For t h e same r e a s o n , i t h a s t o be removed from some i n d u s t r i a l p roduc ts as w e l l . Since i t was found p r e v i o u s l y [ 1 ] , t h a t the f i n e l y d i v i d e d f i b r o u s e l e c t r o d e bed i s a d v a n t a g e o u s o v e r o t h e r t y p e s , removal of mercury from s y n t h e t i c s o l u t i o n s con t a in ing 10 ppm of mercury by e l e c t r o d e p o s i t i o n on f i b r o u s c a r b o n e l e c t r o d e s was s t u d i e d . The aqueous s o l u t i o n c o n t a i n e d NaNO, i n t h e c o n c e n t r a t i o n r a n g e 0.001-2M a s a s u p p o r t i n g e l e c t r o l y t e .

A c o m p a r i s o n was made be tween t h e c o n c e p t u a l ( m o n o p o l a r ) and t h e b i p o l a r e l e c t r o d e a p p r o a c h e s , a t t h e same s o l u t i o n f l o w r a t e , e l e c t r i c c u r r e n t and bed l e n g t h . At c o n c e n t r a t i o n s be low 0.01 M, t h e b i p o l a r e l e c t r o d e y i e l d e d a s l i g h t l y h igher p u r i f i c a t i o n e f f i c i e n c y in comparison w i t h t h a t of t h e m o n o p o l a r e l e c t r o d e . At c o n c e n t r a t i o n s a b o v e 0.1 M, t h e p u r i f i c a t i o n e f f i c i e n c y wi th the b i p o l a r e l e c t r o d e dec r ea se s s i g n i f i c a n t l y w h i l e w i t h t h e m o n o p o l a r e l e c t r o d e an e f f i c i e n c y as h i g h a s 99.6% i s o b t a i n e d . The same e f f i c i e n c y i s o b t a i n e d f o r b o t h e l e c t r o d e s a t i n t e r m e d i a t e s u p p o r t i n g e l e c t r o l y t e c o n c e n t r a t i o n s .

The l o c a t i o n and l e n g t h of t h e a c t i v e p a r t of t h e e l e c t r o d e were ob ta ined by s e c t i o n i n g the bed and a n a l y z i n g each s e c t i o n for mercury. In t h e b i p o l a r c a s e t h i s l e n g t h v a r i e s s l i g h t l y w i t h t h e s u p p o r t i n g e l e c t r o l y t e c o n c e n t r a t i o n wh i l e in t he monopolar e l e c t r o d e i t was a lmos t i n s e n s i t i v e to c o n c e n t r a t i o n . In a l l c a s e s i t did no t exceed 4 cm and the mercury c o n c e n t r a t i o n in the e f f l u e n t was below 50 ppb. REFERENCE: [1 ] Oren Y. and S o f f e r , A. , E l ec t roch im. Acta 2 8 , 1649 (1983) .

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SEPARATION OF NEPTUNIUM FROM ALLOYS AND COMPOUNDS [ 1 ]

J . Lapid, R. Gui se r , Y. Ke ida r , A. Raymond and E. Levy Two p r o c e s s e s for s e p a r a t i o n of neptunium-237 from a l l o y s and from

compounds were deve loped . In t he f i r s t , t he neptunium was s e p a r a t e d from a l l o y s c o n t a i n i n g 30 neptunium compounds. In t h e second, t h e neptunium was s e p a r a t e d from a c a l c i u m and f l u o r i n e r i c h compound. The me thods a r e l eng thy , but can be c a r r i e d ou t by c o n v e n t i o n a l l a b o r a t o r y means. REFERENCE:

[ 1 ] L a p i d , J . , G u i s e r , R., K e i d a r , Y., Raymond , A. a n d L e v y , E . , NRCN(TN)-060, 1985, in Hebrew.

THE ELECTRICAL DOUBLE LAYER CHARGE AND DIMENSIONAL CHANGES IN POROUS GRAPHITE ELECTRODES, OVER A WIDE POTENTIAL RANGE

Y. Oren and A. Sof fe r By moni to r ing the l e n g t h changes of h igh s u r f a c e carbon e l e c t r o d e s ,

i t was p o s s i b l e t o d i s t i n g u i s h be tween s l o w c h a r g i n g p r o c e s s e s of t h e e l e c t r o d e i n t e r f a c e , as man i f e s t ed by the d imens iona l changes, and f a r a d a i c p r o c e s s e s . Both take p l a c e a t p o t e n t i a l s remote from the e l e c t r o c a p i l l a r y maximum. By u s i n g h i g h e l e c t r o l y t e c o n c e n t r a t i o n , ohmic d r o p s were e l i m i n a t e d so t h a t i t c o u l d be deduced t h a t t h e r a t e d e t e r m i n i n g s t e p of t h e s l o w i n t e r f a c i a l p r o c e s s o r i g i n a t e s from t h e i n t e r f a c e i t s e l f . The i r r e v e r s i b l e c u r r e n t i n c r e m e n t s , o b s e r v e d a l w a y s a t t h e e d g e s of wide p o t e n t i a l r a n g e c y c l i c v o l t a m o g r a m s of c a r b o n and g r a p h i t e e l e c t r o d e s , c o u l d o b v i o u s l y be c o n s i d e r e d a r e s u l t of F a r a d a i c or c h a r g e t r a n s f e r p r o c e s s e s . However by m o n i t o r i n g t h e d i m e n s i o n a l c h a n g e s o v e r a wide p o t e n t i a l r a n g e i n t h i s work , i t was p r o v e d t h a t p r i o r t o o r i n p a r a l l e l wi th the f a r a d a i c p r o c e s s , s low charg ing of t he i n t e r f a c e o c c u r s . In t h i s s e n s e t h e c a r b o n and t h e g r a p h i t e e l e c t r o d e b e h a v e d v e r y s i m i l a r l y , p r o v i d i n g a h i n t t h a t the s low s i t e s a r e l o c a t e d a t b a s a l p l a n e s u r f a c e s , which a r e common to g r a p h i t e and carbons .

TRACE ELEMENT ANALYSIS OF SILICATE ROCKS BY DIRECT INSERTION OF A GRAPHITE CUP INTO AN ICP

I . B. Brenner , A. Lorber and Z. Goldbar t T r a c e e l e m e n t a n a l y s i s of g e o l o g i c a l m a t e r i a l s i s f r e q u e n t l y

p r o b l e m a t i c due to chemica l r e s i s t a n c e of t h e component m i n e r a l s , s o l u t i o n i n s t a b i l i t y and i n s u f f i c i e n t q u a n t i t y of s o l i d m a t e r i a l a v a i l a b l e f o r a n a l y s i s . Consequent ly d i r e c t s o l i d sample i n t r o d u c t i o n ICP-AES has many b e n e f i t s .

We a d o p t e d a d i r e c t s o l i d s a m p l e i n s e r t i o n p r o c e d u r e [ 1 ] t h a t i n v o l v e s use of a g r a p h i t e cup which i s d r i v e n h o r i z o n t a l l y i n t o t he ICP.

S ince g e o l o g i c a l m a t e r i a l s have d i v e r s e chemica l and m i n e r a l o g i c a l c o m p o s i t i o n s , we h a v e a d d r e s s e d t h e i n t e r f e r e n c e e f f e c t s due t o

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thermochemical r e a c t i o n s i n t he cup and t h e r m a l d i s r u p t i o n of the plasma as a r e s u l t of gas flow p e r t u r b a t i o n . The v o l a t i l i z a t i o n b e h a v i o r was s t u d i e d a s a f u n c t i o n of power , t i m e , and a d d i t i o n of g r a p h i t e . An a t t e m p t was made t o compensate t he i n t e r f e r e n c e e f f e c t s employing i n t e r n a l r e f e r e n c e s .

A s tudy was made of t he v o l a t i l i z a t i o n b e h a v i o r for v a r i o u s t r a c e e l e m e n t s w i t h and w i t h o u t a d d i t i o n of g r a p h i t e a t 1.25 and 2.0 kW. The t h e r m a l b e h a v i o r of t h e e l e m e n t s i s v e r y s i m i l a r t o t h a t d e s c r i b e d by Boumans and Maessen [ 2 ] . I n t h e absence of g r a p h i t e , i n t e n s i t y " t a i l off", v o l a t i l i z a t i o n i s d e l a y e d (5 s e c fo r v o l a t i l e and 5~15 and more fo r t h e i n v o l a t i l e e l ements ) and doub le peaks occur , e s p e c i a l l y a t low powers. At high powers the r a t e of v o l a t i l i z a t i o n i n c r e a s e s , i n t e n s i t i e s i n c r e a s e , and " t a i l i n g off" and double peaks are i n s i g n i f i c a n t .

With a d d i t i o n of g r a p h i t e t h e s p e c t r a l l i n e i n t e n s i t i e s i n c r e a s e s h a r p l y a t both power l e v e l s . V o l a t i l i z a t i o n commences immedia te ly for t he v o l a t i l e e l emen t s and a f t e r 5 - 10 seconds for the i n v o l a t i l e e l emen t s . The i n t e n s i t y d i s t r i b u t i o n of Cd i s i d e n t i c a l t o t h a t o f Zn due t o s i m i l a r v o l a t i l i z a t i o n b e h a v i o r . This i n d i c a t e s t h a t Cd can be used as an i n t e r n a l r e f e r e n c e for v o l a t i l e e l e m e n t s .

S i l i c a t e s t a n d a r d r e f e r e n c e m a t e r i a l s [ 3 ] were used for m u l t i t r a c e e l e m e n t c a l i b r a t i o n . The e m i s s i o n s i g n a l s were measured employing f a s t r e s p o n s e m e a s u r i n g e l e c t r o n i c s u s i n g peak h e i g h t or peak a r e a . The accuracy of the a n a l y t i c a l d a t a i s ±10—15%. REFERENCES:

[1 ] Lorber , A. and Go ldba r t , Z . , Analys t U_0, 155 (1985) . [2] Boumanns, P . W. J . M. and Maessen , F. J . M. J . , S p e c t r o c h i m . Ac ta 24B,

585 ( 1 9 6 9 ) . [3] Abbey, S . , Geol. Surv . of Canada, 1983, Paper 83~15.

MASS REMOVAL OF NONCONDENSING CONSTITUENTS FROM A GAS-VAPOR MIXTURE BY FILM CONDENSATION

A. K e t t e r , E. Wacholder and E. E l i a s An i n t e g r a l s o l u t i o n was deve loped for p r e d i c t i n g mass r emova l r a t e

of n o n c o n d e n s a b l e g a s from a t e r n a r y g a s - v a p o r m i x t u r e by a c o n d e n s i n g l a m i n a r f i l m f l o w i n g down a l o n g an i s o t h e r m a l v e r t i c a l w a l l . P r o b l e m s i n v o l v i n g t r a n s p o r t of s o l u b l e mat te r from a vapor c o n t a i n i n g a mixture of s o l u b l e and n o n s o l u b l e noncondensing gases a r e encounte red in a number of o p e r a t i o n s in the chemical i n d u s t r y , and in t he a n a l y s i s of f i s s i o n product t r a n s p o r t i n r. n u c l e a r r e a c t o r c o n t a i n m e n t v e s s e l du r ing a h y p o t h e t i c a l a c c i d e n t . The o v e r a l l t r a n s p o r t mechanism in t h i s case i s c o n t r o l l e d by the s t r o n g c o u p l i n g between the mass and h e a t t r a n s p o r t p r o c e s s e s of each of t h e c o n s t i t u e n t s . As t h e c o n d e n s e d l i q u i d v a p o r i n t e r f a c e i s impermeable t o the n o n s o l u b l e noncondensing gas , i t s c o n c e n t r a t i o n b u i l d s up a t t h e i n t e r f a c e . C o n s e q u e n t l y , t h e c o n d e n s a t i o n r a t e i s r e d u c e d and s t r o n g l y a f f e c t s t he removal r a t e of the s o l u b l e g a s .

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In th is work we considered the heat and mass transport processes in the condensate liquid layer and i t s associated gas boundary layer composed of a ternary mixture of steam, air and trace amounts of elemental iodine. The analytical model consists of a system of five coupled boundary-layer equations.

The removal rate of iodine to a containment wall can be expressed in terms of the mass t ransfe r coeff ic ient and the containment physical dimensions. A convenient measure of the removal r a t e i s the time period for decreasing the concentration in the containment to half of i t s i n i t i a l value (half- l i fe) .

Figure 1 shows an example of the ha l f - l i f e behavior vs. the ra t io of bulk-wall temperature difference to the bulk temperature, for two values of bulk a i r concentration (0.77 and 0.47). The c i r c l e represents the CSE experiment [1] for ". = 0.77 and the t r i a n g l e represents a comparison of the d i f f e r e n t i a l so lu t ion [2] for ufl = 0.47. Good agreement with the

fioo

present integral method is observed.

20

15

•= \o I

o X

5

0 0.I 0.2 0.3 AT/Tm

Fig. 1 Concentration h a l f - l i f e vs. r e l a t i v e temperature difference

Resul ts were obtained for a wide range of parameters including bulk composit ion and w a l l and bulk t empe ra tu r e s . Close agreement was found between the present predict ions and the "exact" boundary layer s i m i l a r i t y s o l u t i o n , however, the p re sen t i n t e g r a l t echn ique i s f a s t e r by s e v e r a l orders of magnitude. REFERENCES: [1] H i l l i a r d , R. K. and Knudsen, J . G., Mass Transpor t Model for N a t u r a l

Convection, BNWL-816, 1968, p .2 .41-2.46. [2] Oz i s ik , M. N. and Hughes, D., Nucl . S c i . Eng. 35, 384 (1969).

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A STOCHASTIC MODEL FOR TRANSPORT PHENOMENA IN THE CONTINUUM REGIME: LAMINAR TRANSPORT AND CHEMICAL REACTION

x x * A. C. K r i d i o t i s , J . P. Longwell , A. F . Sarofim and E. Bar -Ziv

A s t o c h a s t i c model was in t roduced for the s i m u l a t i o n of t r a n s p o r t phenomena. I n t h i s work l a m i n a r t r a n s p o r t and c h e m i c a l r e a c t i o n were t r e a t e d . The b a s i c s of t h e model a r e : ( i ) i n s t a n t a n e o u s random m i x i n g b e t w e e n a d j a c e n t c e l l s , ( i i ) a l l o w a n c e f o r p h y s i c o - c h e m i c a l p r o c e s s e s be tween m i x i n g s . The t r a n s f e r of mass , h e a t and momentum, and d i f f u s i o n wi th chemica l r e a c t i o n were s i m u l a t e d and compared to a n a l y t i c a l s o l u t i o n s . The model y i e l d e d a p e r f e c t f i t t o the known r e s u l t s .

A NEW APPROACH TO BACKGROUND AND SPECTRAL INTERFERENCE CORRECTION FOR TRACE ELEMENT ANALYSIS OF GEOLOGICAL MATERIALS A. Lorber , Z . Goldbar t , and I . B. Brenner

G e o l o g i c a l m a t e r i a l s a r e c h a r a c t e r i z e d by d i v e r s e c h e m i c a l composi t ions . Trace element a n a l y s i s of such m a t e r i a l s r e q u i r e s r e l i a b l e s p e c t r a l s t r i p p i n g t echn iques t o overcome i n t e r f e r e n c e e f f e c t s a t t r i b u t e d t o b u l k s a m p l e c o n s t i t u e n t s which , when e x c i t e d i n an ICP, c a u s e complex s p e c t r a . S e v e r a l a p p r o a c h e s h a v e been used t o minimize t h e s e e f f e c t s : h i g h r e s o l u t i o n s p e c t r o m e t e r s , a l t e r n a t e w a v e l e n g t h s e l e c t i o n u s i n g s e q u e n t i a l monoehromators, c o r r e c t i o n by us ing predetermined i n t e r f e r e n c e c o e f f i c i e n t s and o n - l i n e backg round compensation. However none of t h e s e t e c h n i q u e s p rov ides a s a t i s f a c t o r y a n a l y t i c a l s o l u t i o n .

In t h i s work we deve loped a chemometric t echn ique for d e c o n v o l u t i n g both the background and s p e c t r a l i n t e r f e r e n c e c o n t r i b u t i o n s t o t h e a n a l y t e l i n e . The procedure i n v o l v e s scanning of a s p e c t r a l segment on e i t h e r s i d e of peak p o s i t i o n s . S o l u t i o n s of concomi tan ts a r e n e b u l i z e d s e p a r a t e l y in o r d e r t o c h a r a c t e r i z e t h e s p e c t r u m of e a c h i n t e r f e r e n t . The m a t r i x d a t a which c o n s i s t of t h e s e s p e c t r a a l o n g w i t h t h e s p e c t r u m of t h e b a c k g r o u n d and t h e a n a l y t e a r e i n v e r t e d , t h u s r e m o v i n g t h e i r c o n t r i b u t i o n t o t h e a n a l y t e s i g n a l .

The b e n e f i t s o f u s i n g t h i s m e t h o d a r e : a c c u r a t e b a c k g r o u n d compensation, r e c a l i b r a t i o n of the i n t e r f e r e n c e s p e c t r a i s unnecessary and the problem of choosing a p p r o p r i a t e background p o s i t i o n i s avoided .

The r e l i a b i l i t y of the proposed t echn ique was e v a l u a t e d by a n a l y z i n g a wide range of g e o l o g i c a l and env i ronmen ta l m a t e r i a l s . The d a t a ob ta ined compare favorab ly wi th the c e r t i f i e d v a l u e s .

MULTIPLE ION COLLECTION IN THERMAL IONIZATION ISOTOPE RATIO MASS SPECTROMETRY OF STRONTIUM [ 1 ] I . P l a t z n e r

A t h e r m a l i o n i z a t i o n mass s p e c t r o m e t e r f i t t e d w i t h f i v e F a r a d a y

Massachuse t t s I n s t i t u t e of Technology Cambridge, MA, U.S.A. Geolog ica l Survey of I s r a e l , Je rusa lem

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c o l l e c t o r s was c a l i b r a t e d a g a i n s t the NBS SRM 987 s t r o n t i u m s t a n d a r d . Four d i f f e r e n t modes of o p e r a t i o n were compared. The b e s t d a t a f o r t h e

' S r / Sr r a t i o were ob t a ined a p p l y i n g a t r i p l e - c o l l e c t o r / p e a k - j u m p mode. U s i n g a v a l u e of 0.1 1 9M f o r t h e 8 ° S r / 8 8 S r r a t i o a s an i n t e r n a l n o r m a l i z a t i o n f a c t o r , s i x t e e n 1 yg p o r t i o n s of t h e NBS SRM 987 s t a n d a r d y i e l d e d 8 7 S r / 8 6 S r = 0.710249 + 0 .000016 . The i n t e r n a l p r e c i s i o n was + 0 .000003 . For s m a l l SRM 987 s a m p l e s , 100 and 50 ng ( s i x i n e a c h c a s e ) , v a l u e s of 0 .710242 ± 0 .000026 and 0 .710242 + 0.000012 were o b t a i n e d , r e s p e c t i v e l y . REFERENCE: [1] P l a t z n e r , I . , I n t . J . Mass Spectrom. Ion P r o c e s s e s 6_7 129 (1985) .

INSTRUMENTAL EPITHERMAL NEUTRON ACTIVATION ANALYSIS OF CADMIUM IN BIOLOGICAL MATRICES

M. Mantel , N. Lavi and Z. B. A l f a s s i * S e v e r a l p r e v i o u s works have d e a l t wi th e p i t h e r m a l neu t ron a c t i v a t i o n

of cadmium u s i n g d i f f e r e n t cadmium n u c l i d e s . However none compare t h e a d v a n t a g e s and d i s a d v a n t a g e s of t h e v a r i o u s i s o t o p e s ( 1 0 7 , 111m, 1 1 5 , 115m). I n t h i s work we s t u d i e d t h e u s e o f t h e v a r i o u s n u c l i d e s and found ^ 1 m C d t o be the be s t s u i t e d for the f a s t n o n d e s t r u c t i v e d e t e r m i n a t i o n of cadmium i n b i o l o g i c a l m a t e r i a l s . Bo th boron and cadmium s h i e l d i n g of thermal n e u t r o n s were used.

The d e t e c t i o n l i m i t for cadmium in b i o l o g i c a l m a t e r i a l s was found to be a r o u n d 0.5 pg. T h i s d e t e c t i o n l i m i t p e r m i t s t h e e a s y , n o n d e s t r u c t i v e d e t e r m i n a t i o n of cadmium i n l i v e r and k i d n e y t i s s u e . However t h e c o n c e n t r a t i o n of cadmium in most o t h e r b i o l o g i c a l m a t r i c e s i s t oo low for i n s t r u m e n t a l e p i t h e r m a l neu t ron a c t i v a t i o n a n a l y s i s and r e q u i r e s chemical s e p a r a t i o n . For the rmal neu t ron a c t i v a t i o n a n a l y s i s , chemical s e p a r a t i o n i s e s s e n t i a l , even for l i v e r and k idneys , due to t he i n t e r f e r e n c e from the Compton c o n t i n u u m of Na. S i n c e mCd a l s o e m i t s X - r a y s , Y_ray

s p e c t r o m e t r y was compared t o X - r a y s p e c t r o m e t r y f o r t h e measu remen t of cadmium in t h e a c t i v a t e d samples , and found t o be more advan tageous .


139

SYNTHESIS OF TRITIATED INDOLYLBUTYRIC ACID, LABELLED IN POSITION 5

M. Shimoni and 0. Buchman

One of the b e s t chemica l s for use i n p l a n t growth r e g u l a t i o n i s indo ly lbu tyr ic acid. This compound i n i t i a t e s or acce l e r a t e s the root ing of cu t t ings and i s decomposed r e l a t i v e l y slowly by the auxin-destroying enzyme system in p l a n t s . The one way we have found to t r i t i u n r l a b e l t h i s acid a t high spec i f ic a c t i v i t y i s to prepare the 5-bromo d e r i v a t i v e as a precursor for t r i t i a t i o n . The synthes i s was adapted and based on the halogenation of indoles [1] in the aromatic ring instead of in the he te rocyc l ic r ing. The synthesis scheme was as fol lows:

CM* - ca* - ca R "2

• N S03Na

R = - ( C H 2 ) 3 - COOH " [c

„ ^ R B r ^ ^ R _ T ^ . (CH„) - - COOH W OH

N SO-Na ^ N ^ ^ N

I 3

Ac

is. H

After purification from the reaction mixture and analytical controls (UV,

tic), the final product was identified as indolylbutyric acid-5-^H and a

specific activity of 7.3 Ci/mmol was reached.

REFERENCE:

[ 1 ] Thes ing , J . , Semler , G. and Mohr, G., Chem. Ber . .95, 2205 (1962) .

TRITIUM SYNTHESIS OF AN ADRENAL CORTEX DERIVATIVE: 21 -.DEOXYCORTISOL^l^-^H 0 . Buchman, M. Shimoni and A. Cohen

A l l of t h e a d r e n a l c o r t i c a l s t e r o i d s c o n t a i n 21 c a r b o n a t o m s , an a, B - u n s a t u r a t e d k e t o n e i n r i n g A, and an a - k e t o l s i d e c h a i n -C0CH20H (carbons 20,21) a t t a c h e d t o r ing D, The 21-hydroxy group i s e s s e n t i a l fo r m i n e r a l o c o r t i c o i d a c t i v i t y ; i t f a v o r s b u t i s n o t r e q u i r e d f o r g l u c o c o r t i c o i d a c t i v i t y .

The l a b e l e d 2 1 - d e o x y c o r t i s o i was r e q u e s t e d wi th a very h igh s p e c i f i c a c t i v i t y t o be u s e d in r a d i o i m m u n o a s s a y . The e a s i e s t a p p r o a c h t o

CH (21)

CO OH

2 1 - D e o x y c o r t i s o i - 1 , 2 - 3 H

1«3

s y n t h e s i z i n g such a r a d i o a c t i v e d e r i v a t i v e i s to s t a r t from the r e a d i l y avai lable prednisolone, following the scheme:

CH2OH

OH HO

p.TosCl [1]

CH_ l -» CO

H U I ... OH

RCTP [2]

prednisolone 21-deoxyprednisolone

OH

2 1 - d e o x y c o r t i s o l

The r e s u l t i n g c r u d e p r o d u c t was c a r e f u l l y s e p a r a t e d from t h e r e a c t i o n mixture c o n t a i n i n g the homogeneous RCTP c a t a l y s t , and p u r i f i e d on t i c . The p r o d u c t , 21 K d e o x y c o r t i s o l - ^ 1 ,2-^H was o b t a i n e d a t a s p e c i f i c a c t i v i t y of

H9 Ci/mmol. REFERENCES: [1 ] Browers, A. and Ringold, H. J . , J . Am. Chem. Soc. 80 , 3091 (1958) . [2 ] B i r c h , A. J . and Walker, K. A. M., J . Chem. Soc. (C) , 1894 (1966) .

RAPID AND MILD RADI0I0DINATI0N OF SENSITIVE PROTEINS

A. Canf i , A. Freud, M. Zaf ran , Z . Te i te lbaum, S. Weil l and Z. Nevo A m i l d , s i m p l e r a d i o i o d i n a t i o n method t h a t u t i l i z e s r e a d i l y

a v a i l a b l e m a t e r i a l was s u g g e s t e d by T e j e d o r [ 1 ] f o r t h e l a b e l i n g of lysozyme and p r o t e i n A. In t h i s method, ch loramine-T i s used to gene ra t e c h l o r i n e gas from c h l o r i d e adsorbed on a f i l t e r paper. The c h l o r i n e e n t e r s the s o l u t i o n c o n t a i n i n g the i o d i n a t i o n mixture and c o n v e r t s t h e i od ide ions t o e l e c t r o p h y l l i c a l l y r e a c t i v e fo rms . We used t h i s p r o c e d u r e t o r a d i o i o d i n a t e the enzyme lysozyme and a l s o adopted i t for t h e i o d i n a t i o n of human c h o r i o n i c gonadot rop in (hCG) for r e c e p t o r a s s a y s .

The i o d i n a t i o n i s c a r r i e d out in a 13x75 mm p o l y p r o p y l e n e tube cu t 0 .5 cm from t h e b o t t o m , in which t h e p r o t e i n and t h e i o d i n e a r e p l a c e d . F i l t e r p a p e r i s i m p r e g n a t e d w i t h sodium c h l o r i d e and c u t i n t o p i e c e s of a d e q u a t e s i z e . One p i e c e i s p l a c e d on a 2x2 cm g l a s s c o v e r w e t t e d w i t h c h l o r a m i n e - T which i s i m m e d i a t e l y p l a c e d o v e r t h e r e a c t i o n m i x t u r e , t h e paper fac ing in s ide . After 10 min the procedure i s r e p e a t e d and a t the end of an a d d i t i o n a l 10 min t h e r e a c t i o n m i x t u r e i s t r a n s f e r r e d t o t h e p u r i f i c a t i o n co lumn. The s p e c i f i c a c t i v i t y a t t a i n e d was 1 0 0 - 2 0 0 mCi/microgram.

The r a d i o i o d i n a t e d l y sozyme was used a t Sheba M e d i c a l C e n t e r f o r s t u d i e s of the s p e c i f i c b ind ing of t he enzyme t o c a r t i l a g e i n - v i v o and was

*# Ben-Gurion University of the Negev, Beer-Sheva

Sheba Medical Center, Ramat Can

1 i»i4

reported to r e t a in f u l l b i o l o g i c a l a c t i v i t y . The hCG was used for receptor assay of r a t t e s t e s membranes. Net binding of the hormone to the receptor was 10? of t o t a l a c t i v i t y per mg p r o t e i n a s compared with 13% with hCG iodinated by the lactoperoxidase method [2 ] . REFERENCES: [1] Tejedor, F. and Ba l l e s t a , J . P. G., Anal. Biochem. 127, 143 (1982). [2] Chap, Z., Effect of exposure to high environmental temperature on the

hypotha lamic hypophyseal t e s t i c u l a r a x i s in r a t and mouse. Ph.D. Thesis, Ben-Gurion Universi ty of the Negev, 1980.

RADI0I0DINATI0N OF SERUM AMYLOID PROTEIN A. Freud, A. Canfi, Z. Teitelbaum and D. Caspi

Purif ied human serum amyloid protein (SAP) was radioiodinated using a ChT method. Twenty t h r e e pi of a SAP s o l u t i o n (1.44 mg/ml in a Tris/NaCl/EDTA pH 8 buffer) were added to a 1.5 ml conical polypropylene t e s t - tube which contained: - 50 yl of 0.1 M Na2HP0i,, 0.025 M EDTA pH 7.2 buffer. - 37 yl of "*311 (Nal in a d i lu t e NaOH solut ion devoid of reducing agents) . This was followed by prompt addit ion of 10 yl of a ChT solu t ion (2 mg/ml in the above buffer) and the mixture was thoroughly s t i r r e d for 30 sec. The iodination was quenched by 20 yl of Na2S20g so lu t ion (4 mg/ml in the above buf fe r ) and 10 y1 of a 1 % aqueous s o l u t i o n of KI. 1 5"20% of the 1 3 1 1 used was i nco rpo ra t ed i n t o the p r o t e i n as determined by ascending paper chromatography on Whatman 1 paper using methanol as so lven t (Rf. protein '-• 0.0,Rf. I~ •- 0.25). To remove the unreacted iodide, the quenched react ion mixture was a p p l i e d on a Dowex 1x8 anion exchange column (2ml of s e t t l e d res in bed in a 5 ml disposable p l a s t i c 3yringe) which was equ i l ib ra ted with 6 ml of the above PO .EDTA buf fe r . Upon e l u t i o n with the same buf fe r , r a d i o i o d i n a t e d SAP was c o l l e c t e d in four 1 ml f r a c t i o n s ; 97% of the r a d i o a c t i v i t y in t h e s e f r a c t i o n s was pro te in^bound (determined by the aforementioned paper chromatography).

The radioiodinated SAP was used to study the jji vivo d i s t r i b u t i o n of human SAP in experimentally induced murine amyloidosis.

ATTEMPTS TO SYNTHESIZE TRITIUM LABELLED 4-BENZOYLBENZOIC ACID M. Shimoni, J . Azran, A. Cohen and 0. Buchman

An a t t r a c t i v e way to provide a halogenated precursor to be used in the t r i t i a t i o n of 4-benzoylbenzoic acid at a spec i f ic posi t ion seemed t o be to follow a new and convenient procedure [1] as described in scheme 1. The major advantage of t h i s synthesis was in performing the most d e l i c a t e s tep , the t r i t i a t i o n , as the l a s t s tep by t r i t iodehalogenat ion . In sp i t e of our repeated at tempts, a l l e f for t s to obtain the condensation product by s tep 3 f a i l e d . There fo re , another approach was taken , f o l l o w i n g scheme 2 [ 2 ] ,

Ichi lov Hospital , Tel-Aviv

145

s t a r t i n g with a t r i t i a t e d p r e c u r s o r in the f i r s t s t e p of the s y n t h e s i s . The choice of m-bromotoluene in s tep 1 was d ic ta ted by the expectation of o b t a i n i n g the f i n a l molecu le l a b e l e d in a d e a c t i v a t e d p o s i t i o n . The procedure was developed on a micro-scale l e v e l (0.1 ml of bromotoluene) and was successful ly carr ied out, y i e ld ing the purif ied 4-benzoylbenzoic ac id-3-3H at a spec i f ic a c t i v i t y of 15.3 Ci/mmmol.

Bv-(P)- C 0 0 H Br V Q V COOMe L i - / ( 5 \ - COOMe Br ~ ( o ) - Cj "(O)-COOMe COOMe

BuLi H2S0, s t e p 1

NaOH

s t e p 3 THF,-100°C s t e p 2 X

•— B r —\0/~ C - \ 0 / - COOH *"~ 4-benzoylbenzoic a c i d - 4 ' step 4 0

i4'-bromo-4-benzoylbenzoic acid

Scheme 1

CH — 

Scheme 2

REFERENCES:

[1] Parham, W. E. and Sayed, Y. A., J . Org. Chem. 39 , 2053 0 9 7 4 ) .

[ 2 ] Westheim, E . , J . Am. Chem Soc . 55 , 2541 (1933) .

STRUCTURE-iREACTIVITY IN THE BROMINATIOH OF SOME TRICYCLIC COMPOUNDS J . Azran, M. Shimoni, I . P r i r B a r , A. Cohen, Y. Hagag and 0 . Buchman

The r e p l a c e m e n t of t h e p h e n o t h i a z i n e m o i e t y by t h i o x a n t h e n e i n c l i n i c a l l y u s e f u l a n t i p s y c h o t i c drugs i s expected t o minimize e f f e c t s upon the ex t r apy romida l system, w h i l e ma in t a in ing a n t i s c h i z o p h r e n i c potency [ 1 ] .

The g o a l of t h i s work was t o p e r f o r m d i r e c t b r o m i n a t i o n of t h ioxan thene d e r i v a t i v e s t o be used a s p r e c u r s o r s for t r i t i u m l a b e l i n g by t r i t i o d e h a l o g e n a t i o n . The method i s ba sed on p r e v i o u s s u c c e s s f u l b r o m i n a t i o n s of p h e n o t h i a z i n e s , p r o v i d i n g t r i t i a t e d m o l e c u l e s of h i g h

146

specific activity [2], as for fluphenazine. Nevertheless, a l l our attempts as direct bromination of thioxanthene derivatives failed, even with the radical bromine, generated at NBS and expected to react actively with the al lyl ic system. We found that only synthesis of the thioxanthenes, where the bromine atom is already bound to the aromatic ring in the in i t ia l steps, gives high specific activity tritiated molecules, as in the case of flupenthixol (17.3 Ci mmol) [3].

Apparently the C-9 double bond linked to the side chain fixes the two aromatic rings in one plane, enhances the delocalization of the electronic system, and allows the preferential electrophilic bromonium attack on the double bond. On the other hand, when the benzene rings act separately, as in the phenothiazines, the bromine reacts principally with the aromatic system, as assessed by NMR spectra [1].

Our attempts were made on three different thioxanthenes: thiothixene, flupenthixol and chlorprothixene.

I J II -3 || CH

C H 2 CH CH 1

(CH 2 ) 2 (CH 2 ) 2 ( C H 2 } 2 2 2

/ r - J ~ I -N N-CH2CH2OH ^ ^-CH CH2OH N(CH 3 ) 2 NN , N - C H 3

Fluphenazine Flupenthixol Chlorprothixene Thiothixene

REFERENCES: [1] Muren, J . F. and Bloom, B. M., J . Med. Chem. 1_3. 17 (1970) [2] Buchman, 0. and Shimoni, M., J . Label . Compounds Radiopharm. J_9_, 139

(1982) [31 Unpublished r e s u l t s . C1!] Buchman, 0., Shimoni, M., B l i z b l a u , M., Cohen, A. and Hagag, Y., in :

IAM356, 1980, p. 221.

PALLADIUM CATALYZED HYDROGENOLYSIS OF HALOBENZOIC ACID ESTERS

I. Pri-Bar and 0. Buchman

The transfer hydrogenolysis [1] and transfer hydroformylation [2] of

aryl halides in the presence of catalytic amounts of a transition metal, a

hydrogen donor and carbon monoxide gas were published recently. Under

similar conditions methyl esters of halobenzoic acid were found to undergo

a novel hydrogenolysis reaction of the methyl carboxylate (Eq. 1):

X-C5Hi,-C02R + DH »- CgH5CH=0 + R0H + HX (1)

1 H7

Thus, 4-bromomethylbenzoate reacts with a hydrogen donor such as polymethylhydrosiloxane (PMHS) to give 45? benzaldehyde in addition to 50£ of the dehalogenated product: methylbenzoate (Table 1). The reaction involves a transfer hydrogenolysis of the ester moiety accompanied by a reductive dehalogenation. The presence of the halogen is essential for both hydrogenolysis reactions; therefore, unsubstituted methylbenzoate is unreactive under the same conditions.

Table 1 Products percentage in the hydrogenolysis of

halobenzoic acid esters

Yield (mole %)

Substrate CgHgCHO Cgl-L-COgMe

2-I-C6H2)C02Me 14 38

S-Brr-.CglfyCOgMe 27 60

4-Br-C6H4C02Me 45 50

The new r e a c t i o n i s l i m i t e d t o e s t e r s ; f r e e a c i d s a r e u n r e a c t i v e . A p o s s i b l e mechanism for t h i s h y d r o g e n o l y s i s i s pr imary bonding of

the h a l o a r o m a t i c e s t e r t o the meta l i n an o x i d a t i v e a d d i t i o n s t e p t o g i v e m e t a l a r e n e ( I ) (Eq. 2) f o l l o w e d by an i n t r a m o l e c u l a r b o n d i n g of m e t h y l c a r b o x y l a t e to the meta l t o g i v e a me ta lbenzoy l i n t e r m e d i a t e ( I I ) :

H^Pd-CgHjjCC^Me — MeO-Pd-CO-C6H5 (2)

( I ) ( I D

The r e a c t i o n of t h i s i n t e r m e d i a t e w i t h t h e H*-donor g i v e s t h e f i n a l p r o d u c t s . REFERENCES: [1] P r i - B a r , I . and Buchman, 0 . , J . Org. Chem. (1986) , in p r e s s . [2 ] Pri^-Bar, I . and Buchman, 0 . , J . Org. Chem. ^9_, 4009 (1984) .

FERTILITY FOLLOWING NEONATAL GAMMA IRRADIATION

A. Freud and U. A. Sod^Morlah* Female r a t s were exposed once to whole body gamma i r r a d i a t i o n from

an i r i d i u m - 1 9 2 s o u r c e (0.05 Gy) on day 8 of l i f e . When m a t u r e , t h e s e r a t s p r o d u c e d s m a l l e r l i t t e r s t h a n c o n t r o l s , 11.3 t 0.3 (n = 43) v s . 8.6 t 0.6 (n = 3 6 ) . In an a t t e m p t t o d e t e r m i n e w h e t h e r i m p a i r e d o v u l a t i o n o r i m p a i r e d i m p l a n t a t i o n may c o n t r i b u t e t o t h e r e d u c e d r e p r o d u c t i v e


148

performance, a p a r t from hormonal f a c t o r s [ 1 ] , n e o n a t a l l y i r r a d i a t e d females were mated wi th f e r t i l e ma le s . S e v e r a l hours a f t e r p a r t u r i t i o n t h e an ima l s were s a c r i f i c e d and t h e numbers of c o r p o r a l u t e a (CL) and m e t r i a l g l a n d s (MG) were counted . The r e s u l t s i n d i c a t e d t h a t t h e number of CL and MG were t h e same i n c o n t r o l a n d i r r a d i a t e d r a t s , ( 1 3 . 2 + 0 . 5 , n *= 12 v s . 12.6 + 0 .6 , n = 18 f o r CL and 12.1 ± 0 .6 , n = 12 v s 11.8 + 0 . 6 , n = 18

f o r MG, r e s p e c t i v e l y ) ; t h u s , t h e s e d a t a do n o t e x p l a i n t h e s m a l l e r numbers o f pups b o r n t o i r r a d i a t e d m o t h e r s . I n a d d i t i o n i n t h e t r e a t e d group, 12.7$ of the pups were born dead compared wi th o n l y 2.4% in c o n t r o l r a t s .

I t was t h e r e f o r e sugges ted t h a t the impaired r e p r o d u c t i v e c a p a c i t y of n e o n a t a l l y i r r a d i a t e d r a t s r e s u l t s from a complex of f a c t o r s [ 1 ] , none of which, however, could by i t s e l f account for t h e lower f e r t i l i t y . REFERENCE:

[1] F r e u d , A., B e d r a k , E. and S o d - M o r i a h , U. A., Ac ta E n d o c r i n o l o g i c a Congress , H e l s i n k i , 1985. A b s t r a c t #289.

ALTERED, OVARIAN RESPONSIVENESS TO GONADOTROPINS IN NEONATALLY IRRADIATED IMMATURE FEMALE RATS

A. Freud and U. A. Sod-Moriah The e f f e c t s o f n e o n a t a l e x p o s u r e t o gamma i r r a d i a t i o n were

i n v e s t i g a t e d i n immature f e m a l e r a t s . Eight==day"Old f e m a l e r a t s were exposed once t o w h o l e body gamma i r r a d i a t i o n from an i r i d i u m - 1 9 2 s o u r c e (0.05 Gy). At t h e age of 26 d a y s , t h e s e r a t s were t r e a t e d w i t h PMSG (12 I . U . / r a t ) . Ano the r g r o u p of r a t s were f u r t h e r i n j e c t e d w i t h HCG (5 I . U . / r a t ) 48 h o u r s l a t e r . A n i m a l s were k i l l e d 4 8 , 5 5 , 60 and 72 h o u r s a f t e r PMSG t r e a t m e n t or 72 and 120 hours a f t e r HCG i n j e c t i o n . The r e s u l t s i n d i c a t e t h a t PMSG t r e a t m e n t i n c r e a s e d t h e o v a r i a n w e i g h t o f c o n t r o l a s w e l l a s i r r a d i a t e d r a t s and i n b o t h i n d u c e d a s i m i l a r p r o - o e s t r o u s l i k e hormonal p r o f i l e , except t h a t t e s t o s t e r o n e plasma l e v e l s were s i g n i f i c a n t l y h i g h e r i n t h e i r r a d i a t e d g r o u p . PMSG a l o n e d i d n o t c a u s e o v u l a t i o n i n e i t h e r of t h e g r o u p s . A combined t r e a t m e n t of PMSG and HCG r e s u l t e d i n o v u l a t i o n and corpora l u t e a format ion wi th a s i g n i f i c a n t l y i n c r e a s e d number of corpora l u t e a in t he o v a r i e s of the i r r a d i a t e d r a t s . The l a t t e r was not a s s o c i a t e d wi th h igher p r o g e s t e r o n e plasma l e v e l s . I t was sugges ted t h a t n e o n a t a l , low dose gamma i r r a d i a t i o n i n c r e a s e s t h e s e n s i t i v i t y of t he ovary t o exogenous gonadot rop ins .

THE EFFECTS OF NEONATAL LOW DOSE GAMMA IRRADIATION OR HIGH AMBIENT TEMPERATURE ON THE OVARIAN BINDING OF RADIOI0DINATED HCG

A. Freud, I . Snaked , A. Canf i , U. A. Sod-Moriah and R. Chayoth F e m a l e r a t s were e x p o s e d once t o w h o l e - b o d y gamma i r r a d i a t i o n

(0.05 Gy) on day 8 of l i f e , o r a t t h e age of 10 d a y s t h e a n i m a l s were

Ben-Gurion U n i v e r s i t y of t he Negev, Beer-Sheva

149

t ransfer red to a hot room maintained at 35°C. At the age of 26 or 27 days the ra ts were injected with PMSG (12 I.U./animal) and were further injected with HCG (5 I.U./animal), 48 hours l a t e r . Ovarian hyperstimulation occurred in the irradiated group, whereas in the heat acclimated group the ovarian response was decreased, as judged from the number of corpora lutea which were formed (cont ro l : 25.4 + 0.9, n = 62; i r r ad ia t ed : 38.5 t 2.5, n = 22 and heat : 6.1 + 0.8, n = 18). The aim of the present study was to find out whether differences in the number of binding s i t e s or dif ferent affinity constants could explain the above phenomenon.

Binding experiments were performed on ovarian homogenates derived from PMSG-treated r a t s . Our r e s u l t s indicate that in both cases ( i r r a d i a t i o n and heat exposure), the number of binding s i t e s decreased (1.110 fmole/mg ovary in controls, 0.41 and 0.39 fmole/ovary in the treated rats) . On the other hand, the affnity constants were higher in the treated animals (control: 4.4x10 , heat: 10.2x10° and irradiated: 36.0x108 L/mol).

I t was suggested that in spi te of the reduced number of binding s i tes , the very high affinity constant in the irradiated group as compared to that in the heat group would lead to hyperst imulat ion, whereas in the heat group the effect would be rather low.

RADIOIMMUNOASSAY OF CHLORAMPHENICOL USING CHLORAMPHENICOL*SUCCINYL-iAMID0-TYRAMINE»[3H] AS RADIOTRACER O. Buchman, A. C a n f i , M. S h i m o n i , M. Z a f r a n , Y. Hagag, A. Cohen and Z. Teitelbaum

Chloramphenicol is an a n t i b i o t i c for veter inary use. As i t is toxic , i t is important to monitor the l e v e l in the animal's blood, especially if given to domestic livestock. Until recently, only the C labeled tracer was commercially avai lable and being expensive could not be used for routine radioimmunological (RIA) determinations of the drug. In our laboratory a t r i t i a t e d de r iva t i ve was synthesized tha t was found suitable for RIA determination of chloramphenicol.

Due to the chemical s t ruc tu re of the molecule, d i r ec t t r i t i a t i o n , even by bromination followed by tritiodebromination, was unsuccessful. A tedious mul t i - s tep synthesis [1] with incorporation of t r i t ium was a l so discarded.

A promising approach was to prepare the succinate d e r i v a t i v e [2 ] , while this moiety is radioactive. Unfortunately, succinic acid lost i t s t r i t ium atoms by rapid exchange with the hydrogens of the medium, as the atoms bound to the carbons in posi t ion a to the carboxylic functions are highly activated. Another approach, giving positive resul t s , was to bind tritium-labeled tyramine conjugated to a hemisuccinyl derivative via the mixed•anhydride intermediate [3]. Upon diluting tyramine at 39.8 Ci/mmol, the f ina l labeled molecule was obtained with a specif ic a c t i v i t y of 670 mCi/mmol, and i t was used as a radiotracer.

The compatibility of the derivative for the RIA of chloramphenicol was studied with unlabeled chloramphenicol-succinyl-amido-tyramine as

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follows. A RIA system was constructed consis t ing of: C-chloramphenicol as t r ace r , rabbi t antichloramphenicol'-HSA:BSA, a ca l i b r a t i on curve in the c o n c e n t r a t i o n range 1-20 ng / tube and the tyramine d e r i v a t i v e as the unknown. The lowest de tec tab le dose was 2 ng and the c ross - ' r eac t iv i ty of the tyramine d e r i v a t i v e with the chloramphenicol was 100% over the e n t i r e concentration range. Such cross r e a c t i v i t y implies a s imi la r a f f i n i t y of both molecules for the antibody which makes the tyramine chloramphenicol de r i va t i ve abso lu te ly app l icab le to the radioimmunological determination of chloramphenicol. REFERENCES: [1] (a) Long, L. M. and Troutman, H. D., J . Am. Chem. Soc. 7±, 2169 (1949).

(b) C o n t r o u l i s , J . , Rebstock, M. C. and Crooks, J r . , H. M., J . Am. Chem. Soc. 7 1 , 2463 (1949).

[2] Rakoczi, J . , Hung. Pat . 150,422, 1963; C.A., 2857c, 1964. [3] Allen, R.M. and Redshaw, M. R., Steroids 32, 467 (1978).

ADJUVANT RADIOTHERAPY, RADIOPROTECTION, PHOTOSENSITIZATION AND DNA REPAIR MODIFICATION AS MODALITY FOR CANCER THERAPY [1] E. Rikl is

In the search for the best modality for cancer therapy, DNA damage and repai r may be the l inking thread between various d i f ferent approaches. Radioprotective compounds, such as WR-2721, affect DNA repa i r capacity, in addit ion to ac t ing as free r a d i c a l scavengers [2 ] , Recent s tudies in our laboratory c l e a r l y show on a molecular l e v e l , tha t WR-2721, un l ike other pro tec tors , both reduces s ing le strand breaks in DNA and increases strand break re jo ining as part of the increased repa i r synthesis , and i s even more e f f e c t i v e when added t o c e l l s in c u l t u r e a f t e r t he exposure to gamma r a d i a t i o n [ 3 ] . R a d i o s e n s i t i v i t y i s h i g h l y dependent on DNA r e p a i r capacity, as i s wel l demonstrated by the extreme s e n s i t i v i t y of c e l l s which a r e r e p a i r - d e f i c i e n t and whose donors are cancer -p rone p a t i e n t s . Tampering with the r e p a i r c a p a b i l i t y of tumor c e l l s , combined wi th i n c r e a s i n g r e p a i r of h e a l t h y c e l l s i s t h e r e f o r e a d i s t i n c t p o s s i b i l i t y . Another approach which may al low contro l of res i s tance or s e n s i t i v i t y to radia t ion is to change the concentration of inherent ly ex is t ing substances which are i n v o l v e d in r e p a i r . For example, NAD* i s the s u b s t r a t e for poly(ADP)ribose which i s i n v o l v e d in the a c t i v a t i o n of l i g a s e in the exc i s ion r e p a i r system. By adding n i c o t i n a m i d e , a p r e c u r s o r of NAD , m o d i f i c a t i o n may be o b t a i n e d : p r o t e c t i o n a t low c o n c e n t r a t i o n of nicotinamide and s e n s i t i v i t y a t high concentration [4 ] . The synerg i s t i c

e f f e c t s of UV and X - i r r a d i a t i o n s i s a w e l l known phenomenon. Thought should be given to the idea of employing two completely d i f ferent kinds of rad ia t ions along with the appropriate modifying agents, so as to actuate very d i f f e r e n t mechanisms of a c t i o n for p r o t e c t i o n and s e n s i t i z a t i o n . Thus, phthalocyanines are cur ren t ly studied as photosensi t izers with l a se r red l i g h t [5 ] . Combined radio-chemo^phototherapy i s recommended. I t might lead towards an improved modality of cancer therapy.

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REFERENCES: [1 ] R i k l i s , E. i n : 3rd European Conference on C l i n i c a l Oncology and Cancer

Nurs ing, ECCO 3 , Stockholm, 1985. [2 ] R i k l i s , E. i n : R a d i o p r o t e c t o r s and A n t i c a r c i n o g e n s , 0. F. Nygaard and

M. G. Simic , e d i t o r s , Academic P r e s s , 1983, pp. 363^380. [ 3 ] Green, M., P r a g e r , A. and R i k l i s , E., i n : A b s t r a c t s of European S o c i e t y

f o r T h e r a p e u t i c R a d i o l o g y and O n c o l o g y , ESTRO, 3 r d Annua l M e e t i n g , J e r u s a l e m , 1 984 , p . 9 7 .

[4 ] K o l , R., Marko, R. and R i k l i s , E., i n : A b s t r a c t s of European S o c i e t y f o r T h e r a p e u t i c R a d i o l o g y and O n c o l o g y , ESTRO, 3 r d Annua l M e e t i n g , J e r u s a l e m , 1984 , p. 86.

[5 ] K o l , R., Ben-Hur , E. , Marko, R., R o s e n t h a l , I . and R i k l i s , E., L a s e r s Med. S c i . , 1986, in p r e s s .

DNA REPAIR SYNTHESIS AND REJOINING OF STRAND BREAKS IS FAVORABLY AFFECTED BY

WR^2721 IN PREFERENCE TO CYSTEAMINE [ 1 ] E. R i k l i s , A. P r a g e r , M. Green and M. Minsberg

I t h a s b e e n p r e v i o u s l y e s t a b l i s h e d by u s t h a t : a ) t h e r a d i o p r o t e c t o r s WR-2721 and cysteamine i n c r e a s e the s u r v i v a l of mammalian c e l l s in c u l t u r e f o l l o w i n g e x p o s u r e t o gamma r a d i a t i o n , and b) WR--2721 i n c r e a s e s c e l l u l a r DNA r e p a i r c a p a c i t y as measured by l a b e l e d thymidine i n c o r p o r a t i o n i n t o PUVA-treated c e l l s . In o r d e r t o de te rmine the mechanism of a c t i o n of WR-2721, i t s e f f e c t s on s p e c i f i c damage t y p e s and s p e c i f i c r e p a i r s y s t e m s s h o u l d be i d e n t i f i e d . Of t h e v a r i o u s damage and r e p a i r e v e n t s , t h e f o l l o w i n g h a v e so f a r been s t u d i e d : a) DNA s t r a n d b r e a k f o r m a t i o n and r e p a i r - r e j o i n i n g f o l l o w i n g gamma r a d i a t i o n , and b) DNA s t r a n d b r e a k f o r m a t i o n and r e p a i r f o l l o w i n g BUdR + f l u o r e s c e n t l i g h t exposure .

The e f f e c t s of WR-2721, c y s t e a m i n e (MEA) and sod ium d i t h i o n i t e on t h e f o r m a t i o n and r e p a i r of DNA s t r a n d b r e a k s i n gamma i r r a d i a t e d c e l l s were measured by a l k a l i n e suc rose g r a d i e n t s . A l l t h r e e compounds caused a r e d u c t i o n i n t h e number of s t r a n d b r e a k s formed. On ly WR-*2721 was e f f e c t i v e in i n c r e a s i n g t h e r e j o i n i n g of s t r a n d b r e a k s . T h i s was e s t a b l i s h e d by a d d i n g e a c h of t h e compounds o n l y a f t e r t h e e x p o s u r e t o r a d i a t i o n . I n p r e v e n t i n g damage by BUdR and l i g h t e x p o s u r e , WR-2721 and MEA were s l i g h t l y e f f e c t i v e w h i l e N a - d i t h i o n i t e was n o t . None of t h e compounds was e f f e c t i v e in i n c r e a s i n g r e p a i r of BUdR + l i g h t s t r a n d b reaks , b u t MEA and N a - d i t h i o n i t e a c t u a l l y i n h i b i t e d t h e r e j o i n i n g of s t r a n d b r e a k s .

Var ious approaches t o a combined moda l i ty for r a d i o t h e r a p y i n d i c a t e the c e n t r a l r o l e of DNA r e p a i r in de te rmin ing the p o s s i b i l i t y of modifying of c e l l u l a r r e sponse . The most e f f e c t i v e r a d i o p r o t e c t o r , WR-2721, owes i t s e f f e c t i v e n e s s t o t h e f a c t t h a t i t i n c r e a s e s DNA r e p a i r c a p a c i t y and t h e r e j o i n i n g of DNA s t r a n d breaks . The g e n e r a l c o n c l u s i o n s (Table 2) a r e : a) Only WR-2721 of t h e compounds s t u d i e d i s e f f e c t i v e a s a r a d i o p r o t e c t o r by b o t h p r e v e n t i n g damage and i n c r e a s i n g r e p a i r ; b) The modes o f a c t i o n o f

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WR-2721 and of cysteamine are d i f fe ren t ; c) Anoxic condit ions, as caused by Na-di thioni te , do not always support c e l l u l a r r es i s t ance . When res i s t ance is a r e s u l t of repai r , anoxia causes reduced repa i r and therefore increased damage.

Table 2 Response of the radioprotec t ive compounds

Compound Prevention of damage

gamma radiation BUdR+light

Increased rejoining of

DNA strand breaks

gamma radiation BUdR+light

WR'-2721 yes s l i g h t l y yes no cys teamine yes s l i g h t l y no i n h i b i t s d i t h i o n i t e yes no no i n h i b i t s

REFERENCES:

[1 ] R i k l i s , E. , P r a g e r , A., Green , M. and M i n s b e r g , M. i n : I n t e r n a t i o n a l

Conference on Chemical Mod i f i e r s i n Cancer T r e a t m e n t , C l e a r w a t e r FL,

1 9 8 5 , p . 7 - 1 .

DNA REPAIR OF VASCULAR ENDOTHELIAL CELLS FOLLOWING EXPOSURE TO GAMMA AND ULTRAVIOLET RADIATI0N+[1]

A. P r a g e r , M. Green, E. R i k l i s , I . Vlodavsky and A. Eldor The r e s p o n s e of c e l l s o f t h e v a s c u l a r s y s t e m t o r a d i a t i o n i s a

l i m i t i n g f a c t o r in r a d i o t h e r a p y p r o t o c o l s . Va r ious t e c h n i q u e s have been used t o s t udy the v a s c u l a r damage a f t e r r a d i a t i o n , in which morpho log ica l and f u n c t i o n a l changes have been noted. L i t t l e a t t e n t i o n was however g iven t o b i o c h e m i c a l and m e t a b o l i c a l t e r a t i o n s i n v o l v e d in t h e e x p r e s s i o n of r a d i a t i o n induced damage to the v e s s e l w a l l . The e n d o t h e l i a l c e l l s which l i n e the inner su r f ace of b lood v e s s e l s produce p r o s t a c y c l i n e (PGI2) as a p o t e n t i n h i b i t o r of p l a t e l e t a c t i v a t i o n , and t h i s i s r ega rded as one of the i m p o r t a n t v a s c u l a r d e f e n s e m e c h a n i s m s a g a i n s t t h r o m b o s i s and a t h e r o s c l e r o s i s . When c u l t u r e d c e l l s a r e exposed t o i o n i z i n g r a d i a t i o n , t h e p r o d u c t i o n of PGI2 i s d e c r e a s e d a s a f u n c t i o n o f d o s e and o f t h e t i m e i n t e r v a l s be tween i r r a d i a t i o n and s u b s e q u e n t s t i m u l a t i o n , w h i l e t h e e x c r e t i o n of l a r g e q u a n t i t i e s of PGI^ i n t o t h e medium i s e n h a n c e d [ 2 ] , Damage t o t h e c a p a c i t y t o s y n t h e s i z e PGIp from t h e a r a c h i d o n i c a c i d cascade , and the l a r g e r e l e a s e of PGI2 from t h e c e l l s t o t he b a t h i n g medium

+ T h i s work was p e r f o r m e d u n d e r a j o i n t g r a n t from t h e C o u n c i l f o r Higher Educat ion and the I s r a e l Atomic Energy Commission. Hsdassah H o s p i t a l , J e ru sa l em

153

i s an indicat ion of ser ious damage which should be studied, understood and modified. S t u d i e s were t h e r e f o r e under taken in order t o de termine the effects of radiat ion on c e l l v i a b i l i t y and on c e l l u l a r capacity to repai r damage to DNA.

The endothe l ia l c e l l s were cul tured in DMEM supplemented with 10? bovine c a l f serum a t 37°C in 5? humidified incubator. S u r v i v a l was scored as colony forming a b i l i t y following exposure to gamma rad ia t ion , and showed a s u r v i v a l with D of 133 r a d s and e x t r a p o l a t i o n number of 3.2 [ 2 ] . DNA repai r capacity was measured in gamma or u l t r a v i o l e t (254 nm) i r r ad ia ted c e l l s , previous ly t rea ted with t r imethylpsoralen p lus near UV l i g h t , the PUVA procedure [3 ,4] . In t h i s procedure the DNA is crossl inked by the PUVA treatment, thus al lowing determination of DNA repair synthesis while the normal synthesis i s f u l l y inhibi ted.

Figure 1 shows the difference in DNA repair capacity between "young" (3 day c u l t u r e ) s u b c o n f l u e n t , l o g a r i t h m i c a l l y growing c e l l s , and "old" (T4 days) confluent c e l l s , exposed to gamma radia t ion. The subconfluent c e l l s show only a small increase in dose dependent repa i r capacity. The c o n f l u e n t c e l l s show a marked i n c r e a s e in r e p a i r f o l l o w i n g exposure to doses higher than 200 Gy.

I I I I I I 200 400 600 800

Dose [Gy)

Fig. 1 DNA repair capacity of gamma i r rad ia ted endothel ia l c e l l s ,

o "old" c e l l s ; • "young" c e l l s

F igu re 2 shows the d i f f e r e n c e in r e p a i r c a p a c i t y of "young" and "o ld" c e l l s exposed to u l t r a v i o l e t r a d i a t i o n (254 nm). I t i s c l e a r from these s tud ies that capacity to repa i r DNA damage increases with the age in c u l t u r e of the c e l l s . This i n d i c a t e s tha t young c e l l s may be more s e n s i t i v e to radia t ion a l s o _in v ivo , and explains the observat ion that time

154

is required before the start of repopulation of cells underlining an

irradiated aorta.

3

"C o Q .

'6 a. cu

< Z

° I

I 5 10 15 20 Dose(Jm-2)

Fig. 2 DNA repair capacity of UV i r rad ia ted endothel ia l c e l l s ,

o "old" c e l l s ; • "young" c e l l s

REFERENCES: [1] Prager , A., Green, M., R i k l i s , E., Vlodavsky , I . and E ldo r , A., i n :

Trans. Nucl. Soc. I s r a e l , vol . 13, 1986, p. 200. [2] E l d o r , A., V l o d a v s k y , I . , HyAm, E., Atzmon, R. and Fuks , Z. ,

Prostaglandins 25, 263 0 9 8 3 ) . C3] R i k l i s , E., i n : R a d i o p r o t e c t o r s and An t i ca r c inogens , e d i t e d by 0. F.

Nygaard and M. G. Simic, Academic Press , NY, 1983, pp. 363~380. [4] Heimer, Y. M., Kol, R., S h i l o h , Y. and R i k l i s , E., Rad ia t . Res. £ 5 , 511

(1983).

FACTORS AFFECTING THE PHOTOKILLING OF CULTURED CHINESE HAMSTER CELLS BY PHTHALOCYANINES [1] E. Ben-Hur and I . Rosenthal

Chloroaluminum phthalocyanine (CAPC) was recen t ly shown to s e n s i t i z e the i n a c t i v a t i o n of c u l t u r e d Chinese hamster c e l l s by v i s i b l e l i g h t . Several fac tors affect ing the photodynamic act ion of CAPC were defined in the p r e sen t s tudy . Thus the p h o t o s e n s i t i z e d i n a c t i v a t i o n of Chinese hamster c e l l s is not affected by superoxide dismutase, suggesting tha t 0"2

r a d i c a l s a re not involved in the process. Pos t i l luminat ion treatments with D20 or hea t (12°C, 90 min) enhanced CAPC-induced p h o t o s e n s i t i v i t y , i n d i c a t i n g t h e e x i s t e n c e of a r e p a i r mechanism for pho todamage . Pre i l luminat ion treatments with sodium s a l i c y l a t e and 5_bromodeoxyuridine

155

a l s o enhanced p h o t o s e n s i t i v i t y . The l a t t e r o b s e r v a t i o n s u g g e s t s t h a t CAPC-i n d u c e d DNA damage i s p o t e n t i a l l y l e t h a l . However , S^aminobenzamide , a p o t e n t i n h i b i t o r of poly(ADP-ribose) s y n t h e s i s which i s i n v o l v e d i n r e p a i r of DNA s t r a n d b r e a k a g e , h a d no e f f e c t on t h e p h o t o s e n s i t i v i t y . P h o t o s e n s i t i z e d i n a c t i v a t i o n by CAPC i s dependent on the pH v a l u e of t h e medium d u r i n g i r r a d i a t i o n . Thus , i n t h e r a n g e o f pH v a l u e s 6 - 8 , t h e s e n s i t i v i t y was i n c r e a s e d a t t he lower values . . REFERENCE: [ 1 ] Ben-Hur, E. and Rosen tha l , I . , R a d i a t . Res. W3, H03 (1985) .

PHOTOCHEMICAL GENERATION OF SUPEROXIDE RADICAL AND THE CYTOTOXICITY OF PHTHALOCYANINES"1" [ 1 ]

E. Ben-Hur, A. Carmichael , P . R iesz and I . Rosen tha l The e f f e c t of t h e c e n t r a l meta l atom on t h e photodynamic a c t i v i t y of

p h t h a l o c y a n i n e dyes was e s t i m a t e d by c y t o t o x i c i t y t o c u l t u r e d Ch inese h a m s t e r c e l l s . C h l o r o a l u m i n i u m p h t h a l o c y a n i n e , f o l l o w e d by t h e Zrider i v a t e , were found to be the on ly a c t i v e dyes. In p a r a l l e l , i t was found t h a t v i s i b l e l i g h t (615 ± 10nm) e x c i t a t i o n of p h t h a l o c y a n i n e s d i s s o l v e d in d i m e t h y l s u l p h o x i d e in the presence of oxygen g e n e r a t e s supe rox ide r a d i c a l anion. 0~ r a d i c a l s were s p i n t r a p p e d with S . S ' - d i m e t h y l - l - p y r r o l i n e - l -^oxide (DMPO) and i d e n t i f i e d by e l e c t r o n sp in resonance . The quantum y i e l d s for 0 2 g e n e r a t i o n r a n g e from 10 3 ( Z n - p h t h a l o c y a n i n e ) t o H.2x10 (Ga-p h t h a l o c y a n i n e ) . The e f f i c i e n c y of g e n e r a t i n g 0g was a p p a r e n t l y u n c o r r e l a t e d w i t h t h e p h o t o t o x i c i t y of t h e same d y e s . F u r t h e r m o r e , t h e b i o l o g i c a l pho todamage c o u l d n o t be i n h i b i t e d by t h e a d d i t i o n of superoxide d i smutase . I t was concluded t h a t 0 2 i s i n v o l v e d v e r y l i t t l e , if a t a l l , in the p h t h a l o c y a n i n e - i n d u c e d p h o t o - k i l l i n g of mammalian c e l l s . REFERENCE:

[ 1 ] Ben-Hur , E. , C a r m i c h a e l , A., R i e s z , P. and R o s e n t h a l , I . , I n t . J. Radia t . B i o l . 4 8 , 837 (1985) .

CELLULAR LEVELS OF NAD+, CONTROLLED BY NICOTINAMIDE, MODIFY THE RESPONSE OF REPAIR PROFICIENT CELLS TO RADIATION [ 1 ]

R. Kol, R. Marko and E. R i k l i s The i n v o l v e m e n t of t h e chromosomal enzyme p o l y (ADP) r i b o s e

t r a n s f e r a s e in t he l i g a t i o n s t e p of e x c i s i o n r e p a i r has been suggested by v a r i o u s a u t h o r s . We have looked i n t o the r e l a t i o n s h i p between t h e l e v e l of i t s p r e c u r s o r , NAD+, i n s e v e r a l c e l l l i n e s , and t h e i r DNA r e p a i r c a p a c i t i e s , a f t e r n o t i n g t h a t t h e a d d i t i o n o f n i c o t i n a m i d e (NA) at low c o n c e n t r a t i o n s r e n d e r s a h ighe r s u r v i v a l a s w e l l a s h i g h e r r e p a i r capac i ty

This work was performed a t the Na t iona l Cancer I n s t i t u t e , Bethesda, MD, U.S.A.

N a t i o n a l Cancer I n s t i t u t e , Bethesda , MD, U.S.A. Volcani Cente r , Bet-Dagan

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of cer ta in c e l l s . The i n i t i a l l e v e l of NAD+ i s higher in c e l l s which are r e p a i r p r o f i c i e n t than in c e l l s which a r e r e p a i r - d e f i c i e n t , such as Xeroderma pigmentosum c e l l s . Using our PUVA method for measurement of repa i r by incorporation of ^H-thytnidine into c e l l s in which DNA synthesis was i n h i b i t e d by PUVA, a h i g h r e p a i r c a p a b i l i t y was observed in human f i b r o b l a s t s (KD l i n e ) , n o n m e t a s t a t i c mouse melanoma (Cl-16) and HEp-2 c e l l s , lower repa i r c a p a b i l i t y in rodent c e l l s and none in XP c e l l s when exposed t o UV-C (25^ nm) l i g h t . XP c e l l s did show r e p a i r , though low, following exposure to gamma radia t ion .

The l e v e l of NAD+, noted over a period of 4 hours, decreased sharply in gamma-irradiated r epa i r -p ro f i c i en t c e l l s and somewhat l e s s s teeply in r e p a i r i n g U V - i r r a d i a t e d c e l l s . The l e v e l did not dec rease in the •Jion'-repair ing XP c e l l s following UV-C radiat ion-

DNA r e p a i r s y n t h e s i s i s inc reased upon the a d d i t i o n of a low c o n c e n t r a t i o n of n i c o t i n a m i d e to w e l l r e p a i r i n g c e l l s . The h i g h e s t i n c r e a s e was noted in gamma i r r a d i a t e d HEp-2 c e l l s (which ca r ry human markers) and human f i b r o b l a s t s (KD) which showed a high repa i r capacity to begin with. The increase was observed with an optimal NA concentration of 3 mM. Higher c o n c e n t r a t i o n s caused i n h i b i t i o n of r e p a i r s y n t h e s i s . XP c e l l s were not affected by the addition of NA when UV i r r ad ia t ed , but were affected upon exposure to gamma radiation.

I t was concluded t h e r e f o r e t h a t the p o s i t i v e e f f e c t of NA a t low concentrat ions is dependent on a functional repai r system. Thus the use of nicotinamide as a protector (a t low concentration) or as a sens i t i ze r (at high c o n c e n t r a t i o n s ) may p l a y an impor tan t r o l e in the sea rch for cancer therapy modal i t ies . REFERENCE: [1] Kol, R., Marko, R. and R i k l i s , E., i n : I n t e r n a t i o n a l Conference on

Chemical Modifiers in Cancer Treatment, Clearwater, FL, 1985, pp. 8-16.

POLY(ADPs-RIBOSE) AND THE RECOVERY FROM DAMAGE IN CHINESE HAMSTER CELLS DUE TO

5-BR0M0DEOXYURIDINE PHOTOLYSIS"1" [1]

E. Ben->Hur, K. Lindquist and M.M. Elkind

Exposure of Chinese hamster c e l l s t o near-UV l i g h t , following the uniform i n c o r p o r a t i o n of 5-bromodeoxyuridine (BrdUrd) i n t o t h e i r DNA, resu l ted in c e l l k i l l i n g t h a t was close t o exponential . An inhib i tor of p o l y ( A D P - r i b o s e ) s y n t h e s i s , 3_aminobenzamide (3-ABA), enhanced the c y t o t o x i c e f f e c t of t h i s t r ea tmen t when p re sen t for 2 h a t 20 mM a f t e r l i g h t exposure. The dose modifying factor was 1.1|. Under conditions that r e su l t ed in a sigmoidal s u r v i v a l curve (a 30 min Brdl'vd pu lse in S phase, followed 90 min l a t e r by l i g h t exposure), the effect of 3-ABA was to remove

+This work was performed at Colorado S ta t e University, Fort Co l l i n s , CO., U.S.A. Colorado State Universi ty, Fort Coll ins , Co., U.S.A.

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the shou lde r of the s u r v i v a l curve with very l i t t l e change in i t s f i n a l s l o p e . Using v a r i o u s i n h i b i t o r s of ADP-ribosyl t r a n s f e r a s e (ADPRT) we found the enhanced c e l l k i l l i n g to cor re la te with the inh ib i to r s ' r e l a t i v e potency. C e l l u l a r NAD , the subst ra te for poly(ADP-ribose) synthesis, was rapid ly depleted af ter exposure. This depletion was l a rge ly prevented by 3-ABA; the a c t i v i t y of ADPRT increased with the fluence of near-UV l i g h t ; and the c o n c e n t r a t i o n of c e l l u l a r NAD+ decreased with exposure. ADPRT a c t i v i t y was maximal immediately af ter exposure to near-UV l i g h t and then decayed to preexposure l e v e l s wi th in 30 min (37°C). The enhanced cytotoxici ty of BrdUrd + near-UV l i g h t , when followed by 3-ABA treatment, d i sappeared a t a r a t e s i m i l a r to t h a t of the decay in ADPRT a c t i v i t y . We conclude from these r e s u l t s that poly (ADP-ribose) synthesis i s important for the recovery from BrdUrd photolysis damage in DNA. Because th i s damage and i t s r e p a i r a re r e l a t i v e l y s p e c i f i c (e.g. compared to i o n i z i n g radiat ion) and r e l a t i v e l y easy to manipulate, the system could serve as a model for the s tudy of the r o l e of poly(ADP-ribose) in the r e p a i r of DNA damage. REFERENCE:

[1] Ben-Hur, E., L i n d q u i s t , K. and Elk ind , M.M., I n t . J . Radia t . B i o l . £8 , 33 (1985)

A NEW METHOD FOR IN VITRO LABELING OF RED BLOOD CELLS J . Trumper and J . Weininger

New appl ica t ions for imaging with Tc~99m labeled red blood in the i n v e s t i g a t i o n of v a r i o u s p a t h o l o g i e s have been recognized. Despite the widespread use of in v i v o l a b e l e d red c e l l s , in v i t r o l a b e l e d RBC are p robab ly the agent of choice for blood pool imaging, due t o minimized e x t r a v a s c u l a r d i s t r i b u t i o n of Tc-99m. We previously developed two very s imple and e f f i c i e n t Tc~99m l a b e l i n g methods for red blood c e l l s , but 5-10ml of blood were used and the procedures needed both centrifugation and t ransfer [1 ] . Decreasing both the tagging manipulations and the volume of b lood used for l a b e l i n g may make the new method p r e f e r a b l e to in v i v o l abe l ing in routine c l i n i c a l work.

The p resen t study concen t r a t ed on us ing more t i n in the k i t , thus reducing the detrimental effect of the ca r r i e r Tc~99, and on reducing the volume of the b lood sample, t hus making the method u s e f u l in p e d i a t r i c s a l so .

The method i s a one-via l technique, tha t e l iminates the need for any centr ifugation or t ransfer . The glucoheptonate k i t , rou t ine ly prepared by us for kidney and b r a i n imaging, i s used as a p r e - t i n n i n g agent for 2 ml whole blood. The l abe l ing method consis ts of withdrawing the blood into a s y r i n g e c o n t a i n i n g a n t i - c o a g u l a n t ACD and t h e n add ing i t t o t h e g lucohep tona t e k i t (0.1 mg SnClp). After 5 min incuba t ion a t room t empera tu re , 0.5ml of a 0.26? Na h y p o c h l o r i t e s o l u t i o n i s added. This so lu t ion neu t ra l i zes the excess t in which was not used in the pre- t inning process [2 ] . One minute l a t e r the Tc_99m pertechnetate solut ion is added

158

in a volume not exceeding 0.5ml. After 20 min incuba t ion a t room temperature the preparat ion, with a labe l ing y i e l d of 97 -99?, i s ready for injection. When spleen imaging is to be performed the labeled c e l l s can be dena tu r a t ed by hea t (15 min a t iJ9.5°C), the y i e l d of the l a b e l i n g s t i l l being higher than 90%. For bolus inject ion, the volume containing almost a l l t h e a c t i v i t y may be r e d u c e d from 5 t o 0 .5 -1 .0 ml by s i m p l e c e n t r i f u g a t i o n of the v i a l in an i n v e r t e d p o s i t i o n and c o n s e c u t i v e withdrawal of the packed red blood c e l l s through the stopper using an 18G needle.

The c l i n i c a l use of t h i s l a b e l i n g procedure has r e c e n t l y been s t a r t ed , following approval of the Ministry of Health. REFERENCES: [1] Weininger, J . , Trumper, J . , Lubin, E. and Abrashkin, S., I n t . J . Nucl.

Med. Bio l . 5_, (1978) 183. [2] Srivastava, S. C. et a l . , J . Nucl. Med. 25 (198H) 128.

A NEW TYPE OF Mor99/Tc--99m GENERATOR SYSTEM G. Ringler, S. Shrem and H. Zauber

Almost a l l radiopharmaceutical companies are a c t i v e l y involved in the development of improved Mo-99/Tc-99m g e n e r a t o r systems in order to supply n u c l e a r medicine depar tments with g e n e r a t o r s of s imple and easy operation and r e l i ab l e performance.

The improvement of our generator involves seve ra l important points which lead to high e l u t i o n y i e l d with minimal h a n d l i n g . The v i a l s containing the s t e r i l e isotonic s a l i n e so lu t ion for e lu t ing the generator are replaced by a r ig id container inserted a t the bottom of the generator. Elut ion w i l l be by means of a very simple piping system which cons is t s of two double need led m e t a l l i c t ubes , one of which connects the s a l i n e container with the column head and the other the bottom of the column with the "mi lk ing" pos t . The dryness of the column, the main cond i t i on necessary to assure high e lu t ion y ie ld , is obtained in the present system by s p e c i a l l y i n s e r t i n g an evacua ted v i a l a f t e r e l u t i o n . In the new generator system the dryness w i l l be assured by the negative pressure of the r ig id s a l i ne container.

The r e s u l t s we obtained already are encouraging: about 70? e lu t ion y i e l d for 1200 mCi g e n e r a t o r s wi th 6 ml e l u t i o n volume. E f f o r t s are con t inu ing to improve both the e l u t i o n y i e l d and the r e l i a b i l i t y of the generator system.

WET COLUMN RADIOLYSIS G. Ringler, S. Shrem and H. Zauber

The column in our Mo-99/Tc~99m generator system is kept dry between e l u t i o n s . The dry ing i s done with an evacua ted v i a l and the system i s c a l l e d DRY. G e n e r a l l y , i f the column remains wet the y i e l d of the consecutive e lu t ion w i l l decrease due to the r a d i o l y s i s which takes place.

159

The water m o l e c u l e s which are t ransformed i n t o f r e e - r a d i c a l s by the radia t ion reac t with the Tc-99m pertechnetate ion by a redox react ion and the TC-99m ion passes from valence +7 to + 1. In t h i s s t a t e the Tc~99m ion is more s t rongly bound to the alumina bed so that the action of the s a l i n e so lu t ion i s l e s s e f f i c i en t in washing i t out.

A c o r r e l a t i o n was found between the r a d i o l y s i s p r o c e s s and the a c t i v i t y loaded on the column: no de tec table r a d i o l y s i s was found during 2H hours in columns under 5 mCi a c t i v i t y , a f i r s t o rde r t ime r e a c t i o n was found for 5_60 mCi and the r a d i o l y s i s process was completed in 5~6 hours in columns with more than 100 mCi.

Antioxidants, such as sodium dichromate at 10-20 ppm l e v e l s , added to the e lu t i ng so lu t ion assure about 80% e lu t ion y i e ld of wet columns for about 48 hours.

E f f o r t s a re made to decrease the r a d i o l y s i s e f f e c t by b e t t e r dispersion of the alumina ac t ivated bed in ine r t media.

Mo-99/Tc-99m GENERATOR: COLUMN PERFORMANCE G. Ringler, S. Shrem and H. Zauber

The qua l i ty of a Mo-99/Tc~99m generator i s mainly governed by i t s column: an alumina bed on which the Mo i s loaded. In order to determine the performance of our Mo-99/Tc~99m fiss ion product column, the e lu t i on y ie ld , pH, A1 J con t en t , as w e l l a s Mo breakthrough of g e n e r a t o r s of d i f f e r e n t a c t i v i t i e s (from 100 to 1200 mCi) were checked. E l u t i o n p r o f i l e s for fract ionated e lu t ion of 1 ml, demonstrate that 5 ml s a l i n e so lu t ion e l u t e s 85-92% of the a v a i l a b l e a c t i v i t y ; 15 ml s a l i n e e l u t e s 96-99%. The pH of the e l u a t e i s 6.3"7 for a 1 5 ml e l u t i o n . When f r a c t i o n a t e d e l u t i o n i s performed the pH changes from 5.2 in the f i r s t m i l l i l i t e r , through 5.7 in the second, to 6.5~7.2 in the l a s t f ract ions .

The Mo-99 breakthrough of the e l u a t e does not exceed 0.01% on the whole a c t i v i t y sca le . If repeated e lu t ions are performed during one day, t he e l u t i o n y i e l d s l i g h t l y d e c r e a s e s in both 5 ml and 15 ml e l u t i o n volumes. Typical e lu t ion p ro f i l e s are shown in Fig. 3.

40 E I 3o

I-IO

I 2 3 4 5 6 7 8 2 4 6 8 IO 12 14 Elulion volume (ml) Elution volume (ml)

Fig. 3 Typical elution profiles

160

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ion

-B

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§ 20

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: /1 : /

7 i / . 1 , 1 , 1 , 1 . 1 , 1 1 1

A NEW Os-191/IrM91m GENERATOR FOR FIRST-PASS RADIONUCLIDE ANGIOGRAPHY D. Issachar, J . Trumper, A. Braun and S. Abrashkin

F i r s t - p a s s a n g i o g r a p h y f o l l o w i n g b o l u s a d m i n i s t r a t i o n has demonstrated i t s usefulness as a non-invasive evalua t ion of a la rge var ie ty of c o n g e n i t a l and acqui red c a r d i o v a s c u l a r d i s o r d e r s . The r a d i o n u c l i d e cur rent ly used for t h i s purpose is Tc-99m ( h a l f - l i f e 6 h). We developed a new generator system which provides Ir-191m ( h a l f - l i f e 4.9 sec) which could p o t e n t i a l l y rep lace Tc~99m for radionucl ide angiography.

Ir-191m is the product of the rad ioac t ive decay of Os-191 ( h a l f - l i f e 15.^ days) from which i t i s separated by e lu t i ng the generator. The main advantages of Ii—191m for f i r s t - p a s s cardiac s tudies are twofold: lower r a d i a t i o n dose to the p a t i e n t and an op t ion for immediate (wi th in a minute) mul t ip le s tudies .

The time required for a f i r s t - p a s s examination is about 15~30 sec. Because the 6 hour h a l f - l i f e of Tc~99m is excess ively long compared with t h i s examinat ion pe r iod , the p a t i e n t con t inues to r e c e i v e s u p e r f l u o u s i r r a d i a t i o n a f t e r comple t ion of the examinat ion. This unnecessary i r r ad ia t ion could be avoided by using the u l t r a - s h o r t l ived Ir-191m. The lowering of the absorbed radia t ion dose is e s p e c i a l l y important when the examination i s performed on infants .

The op t i on to perform immediate r epea t ed s t u d i e s may be of g rea t diagnostic importance. The use of Ir-191m i s recommended in th i s case both because of low i r r ad i a t i on and the almost complete absence of background remaining from the previous examination.

The new Os-191 /Ir-191m generator system was developed by us and has a l r e a d y been t r i e d a t f u l l a c t i v i t y l e v e l (about 1 Cur ie ) . The main r e s u l t s of the t r i a l can be summarized as follows. a) When 1.5 ml e luant i s passed through the generator, within two seconds

the Ir-191m y i e l d i s 20-23?. This i s accompanied by (7 _ 20)x10 - l , J Os-191 breakthrough.

b) The generator performs as in (a) for at l e a s t 3 weeks. c) No r a d i a t i o n damage of the g e n e r a t o r system could be d e t e c t e d ; the

e lu t ion performance remained constant and no r a d i o l y s i s products could be detected.

d) Chemical, radiochemical, pharmaceutical and b io log i ca l qua l i t y control of the generator e lua t e s proved tha t they are s u i t a b l e for c l i n i c a l use.

RADIATION DOSIMETRY OF THE 0s-191 /IrM91m GENERATOR ELUATE T. Schlesinger, J . Weininger, J . Trumper and D. Issachar

Radiation doses to the whole body and to severa l v i t a l organs were ca lcu la ted for pa t i en t s undergoing Ir-191m angiography. The ca l cu l a t i ons were performed for both a d u l t s and i n f a n t s . I r - 1 9 1 m h a s a h a l f - l i f e of 4.96 sec and decays to Ir-191 with the emission of 42 keV (converted 100?), 129 keV(26?) photons and 65 keV X-rays (50?). Due to i t s very short half -l i f e the contr ibut ion of Ii—191m to the radia t ion absorbed by the pa t ien t

161

i s very low: in our assessment about 10 mRad/100 mCi Ii—191m. The r a d i a t i o n doses are mainly due to the breakthrough of the 15.4 day l o n g -l ived parent Os-191. The breakthrough of even very small amounts of Os-191 - a few microcuries - may r a i s e the i r r ad ia t ion doses to subs tan t ia l l eve l s .

The Ir~191m a c t i v i t y su i t ab l e for angiography i s about 100 mCi for an adu l t and about 70 mCi for an infant. Because of the 0s breakthrough of the gene ra to r system, the Ir~191m a c t i v i t y i s accompanied by a few microcuries of Os-191 (about (7 - 20)x10 - ^ of the generator a c t i v i t y ) .

The e q u i l i b r i u m dose r a t e c o n s t a n t of 0s-19l i s 0.29 r a d - g / v C i - h ( i . e . 0.29 rad per hour for 1 uCi per grain t i s s u e ) . Most of t h i s dose i s due t o the 37.5 keV (average) be ta p a r t i c l e s of 0s~19l (100?). The p e n e t r a t i n g r a d i a t i o n s (129 keV gamma-rays and the 65 keV X-rays) ' contr ibute mainly to the organ se l f -dose in large organs (232 in the lungs and 9% in the l i v e r ) . To assess organ-to-organ doses absorption fract ions w e r e c a l c u l a t e d f o r t h e e n e r g y r a n g e a s s o c i a t e d w i t h t h e 0s-191 -*-Ir-191m ->Ir-191 react ion. The absorbed doses per un i t cumulative a c t i v i t y were ca lcu la ted .

B i o d i s t r i b u t i o n and c l e a r a n c e s t u d i e s of 0s-191 were performed in mice. Organ uptake and e f f e c t i v e h a l f - l i v e s were determined in v i t a l organs and the cumulative doses in these organs were assessed.

The above mentioned data were used to c a l c u l a t e absorbed doses in whole body and in ten t a r g e t o rgans . The c a l c u l a t e d v a l u e s were extrapolated for adul ts and infants. Table 3 summarizes our findings. The r e s u l t s are expressed in mRads per microcurie 0s-191. I t is assumed that the rad ia t ion dose per pCi of Os-191 i s 5 times and 15 times the adu l t dose for a one-year old and new born, r e spec t ive ly .

Table 3 Organ doses due to breakthrough of 0s-191 in diagnostic procedures using

* I r . Doses are given in mrad per microcurie of 0s-191.

Organ Liver Kidneys Spleen Lungs Genitals Bladder Bone Bone Gut Whole marrow Body

Adult 12 3.4 0.9 0.9 0.22 1.0 0.2 2.8 6.8 0.6 1 year old

infant 60 17 4.5 1.5 1.1 5.0 1.0 14 34 3-0 Newborn 180 51 14 14 3.3 15 3.0 42 102 9

From the tab le i t can be seen tha t the l i v e r is the highest exposed organ. If we want to l i m i t the i n f a n t dose to 100 mRad to the l i v e r , the Os-191 breakthrough must be lower than 10~ % of the generator a c t i v i t y . For a d u l t s , even i f the 0s-191 breakthrough i s about \Q~^%, the absorbed

162

dose i s much lower than the one r e c e i v e d by the procedure c u r r e n t l y used for i den t i ca l purposes where 20 mCi Tc-99m DTPA i s administered.

0s*191 BIODISTRIBUTION STUDIES IN MICE J . Weininger, J . Trumper and D. Issachar

One of the main r e a s o n s for r e p l a c i n g Tc-99m wi th Ir-191m for nuclear angiography is tha t the radia t ion l e v e l s to the pa t ient ( e spec ia l ly children) are expected to be s ign i f i can t ly reduced.

Extended tox ic i ty , body clearance and b iod i s t r ibu t ion s tudies with Os-191 were c a r r i e d out in mice. As I r~ l9 lm i s c a r r i e r - f r e e and a l s o e s s e n t i a l l y decays ( T 1 / 2 4.9 sec) within the blood pool, our s tud ies were performed by measuring t h e Os-191 uptake . The b i o l o g i c a l b e h a v i o r of Os-191 i s s imi la r to that of Ir-19lm. Because of the very short h a l f - l i f e of Ir-191m, the main rad ia t ion dose to the pa t ient i s due to Os-191.

The s o l u t i o n t o be i n j e c t e d was ob ta ined by e l u t i n g an Os-I r g e n e r a t o r wi th a 0.9? NaCl s o l u t i o n a t pH 1. The pH of t h i s s o l u t i o n was ad jus t ed with a phosphate buf fe r s o l u t i o n to 6 before i n j e c t i o n . Each mouse was i n j e c t e d in the t a i l ve in wi th 3.8 - 7.5 Ci Os-191 in a volume of 0.1 ml.

The body clearance s tudies showed r e l a t i v e l y rapid disappearance of the mater ia l from the body both by urinary and hepa tob i l i a ry pathways: the u r i n a r y c l e a r a n c e i s about 35$ ID ( i n j e c t e d dose) , w h i l e the c l e a r a n c e through feces i s about 53? 1° in ten days. The main t a rge t organs are the l i v e r and the gut. The maximal uptake in the l i v e r is 29? ID, while in the gut i t i s 25? ID - in both one hour af ter in ject ion. The l i v e r uptake i s about 6.4? ID and the gut uptake i s about 0.6? ID a f t e r t en days. The clearance curves are shown in the Fig. 4.

These r e s u l t s made poss ib le rad ia t ion dose ca l cu l a t i ons [ 1 ] , which are summarized in Table 4, for 20 mCi Tc~99m DTPA with 100 mCi Ir-191m for adu l t s and 2 mCi Tc-99m DTPA with 70 mCi Ir-191m for a one-year o ld ch i ld . The r e s u l t s ob ta ined make p o s s i b l e r e p e a t e d s t u d i e s which a re of ten necessary for accurate diagnosis .

Table 4 Radiation dose (mRad) per examination from Tc-99m-DTPA

and Ir-191m in adu l t s and chi ldren

Adul ts

Tc-99m-DTPA

Whole body 320 Liver Gut

Ir-191m

4.8 62.4 54.4

Ch i ld ren

Tc-99m-DTPA

124

Ir-191m

18.0 234.0 204.0

163

Fig. U Clearance curves

1 2 4 6 8 10 12 14 Days

REFERENCE: [1] Schlesinger, T. , t h i s annual repor t , p . 161.

CARDIAC STUDIES ON DOGS USING Ir-191m C. Helman, E. Lubin, J . Trumper, B. Abrashkin, A. Braun and D. Issachar

The u l t r a - s h o r t - l i v e d r a d i o n u c l i d e Ir-191m ob ta ined from an Os-191/I r -191 m g e n e r a t o r system was t r i e d for c a r d i a c s t u d i e s on dogs. F i r s t -pas s ventriculography using a d i g i t a l gamma camera was performed by inject ing a bolus of 80 mCi Ir-191m. The examination was performed under the following experimental condi t ions: a) the camera was set up to receive s igna ls from 60 to 130 keV b) the APC-H high resolu t ion coll imator was used c) the information was col lec ted on a 64x6H matrix.

The counting ra t e in the l e f t v e n t r i c l e was about 170 K/sec. The background was about 10-12? of the a c t i v i t y peak, lower than the 30? b a c k g r o u n d p r e s e n t i n t h e r o u t i n e l y pe r fo rmed Tc~99m f i r s t - p a s s examinations. The high counting ra te made poss ible good cardiac function e v a l u a t i o n ( e j e c t i o n f r a c t i o n c a l c u l a t i o n ) wi th e x c e l l e n t ana tomica l d e t a i l s .

These findings led us to apply for approval for experimental human use of our 0s-191/Ir-l91m generator. The Helsinki Committee of Beil inson Hospital approved a preliminary t r i a l in both adu l t s and infants. During the c l i n i c a l t r i a l the imaging q u a l i t y w i l l be improved by us ing a dual peak with 15% windowing around each of the c h a r a c t e r i s t i c energy peaks (65 and 129 keV). We w i l l a l s o c o l l e c t in format ion on a 128x128 mat r ix in order to achieve bet ter anatomical reso lu t ion .

164

*

Table 5

Magnetic resonance properties, water content and biochemical data

in different experimental groups

T, T 2 PW FB HF

Cortex

Control 466 ±6 49 ±2 76.2±0.7 0.112±008 0.358±0.02

(N-7) Gentamicin ARF 587.4±33-9* 74.3±7.2* 77.1+0.9 0.099+0.002 0.328±0.02

(N-13) Glycerol ARF 403 .5+27 .4* 58 .9+3-3* 71 .4+0 .4* 0.175 + 0.01* 0.436±0.03*

(N-13) O b s t r u c t i o n ARF (N=14) U r e t e r a l

l i g a t i o n 678 +12* 83-2+2.4* 8l .2±0.8* 0.079±0.007* 0.318±0.005 C o n t r a l a t e r a l

k i d n e y 523 +7 .9* 53 +2.1 75 +0.6 0.103±0O4 0.310±0.05*

Medulla C o n t r o l 654 +29 73 ±3 79.1+1.7 0.073+004 0.276±0.015

(N-7) Gentamicin ARF 666.9±20 81.3+4.4 79 ±0.4 0.078+009 0.290±0.25

(N-13) G l y c e r o l AR 527 .6+15 .9* 82 .1+2 .2* 76 ±0.4* 0.098+0.02 0.313±0.03*

(N-13) Obs t ruc t i on ARF (N=14)

U r e t e r a l l i g a t i o n 873-2+13* 111.7 + 3-9* 82.1+0.7* 0.052±0.003* 0.237+0.01*

C o n t r a l a t e r a l k idney 677 ±16 69 .8+2.8 76 .8±0 .5 0.078+0.003 0.258±0.02

Control

Gentamicin ARF

Glycerol ARF

Obstruction ARF

The numbers are given in MEAN ± SE. T1, T2 are given in msec.

PW = Tissue total water in %; FB = Fraction bound; HF = Hydration fraction. Blood urea and creatinine in mg/dl.

Urea

36.5+4

11.2+19.2*

153 ±13* *

52 +2

Creatinine

0.41+0.04

1.30+0.20*

1.75+0.19*

0.61+0.06*

165

PROTON MR STUDY OF DIFFERENT TYPES OF EXPERIMENTAL ACUTE RENAL FAILURE (ARF)

IN RATS

A. I a i n a , S . Abrashkin and J . Weininger Kidney c o r t i c a l and m e d u l l a r y s p i n - l a t t i c e (T^) and s p i n - s p i n (T2)

r e l a x a t i o n t imes were measured in s e v e r a l types of expe r imen ta l a c u t e r e n a l f a i l u r e (ARF) i n r a t s w i t h a Bruker PC " M u l t i s p e c " a t 20 MHz. We o b t a i n e d : Gentamicin ARF a f t e r one i.p. i n j e c t i o n of 100 mg Gentamicln/kg BW/day for 8 d a y s , g l y c e r o l ARF: 21 h o u r s a f t e r one i.m. i n j e c t i o n of 10 ml 50$ g l y c e r o l / k g BW, o b s t r u c t i o n ARF: 3 days a f t e r comple te u r e t e r a l l i g a t i o n . Renal t i s s u e t o t a l water con ten t , h y d r a t i o n f r a c t i o n , f r a c t i o n bound, b lood u rea and c r e a t i n i n e were measured a t t h e end of the exper iments . Shor tened T1 and pro longed T2 were found in both c o r t e x and medu l l a in the g l y c e r o l ARF group. Gentamicin r e n a l t o x i c i t y and the non- func t ion ing kidney wi th u r e t e r a l o b s t r u c t i o n a r e c h a r a c t e r i z e d by s i g n i f i c a n t p r o l o n g a t i o n of T1

and T- i n c o r t e x , w h i l e t h e m e d u l l a r y T. and T~ were p r o l o n g e d o n l y i n o b s t r u c t i o n ARF. The h i g h e s t T^ and T-, were found i n t h e o b s t r u c t e d n o n f u n c t i o n i n g kidney. The r e s u l t s a re g iven in Table 5. -

The t o t a l water con t en t dec reased in t he g l y c e r o l ARF, i n c r e a s e d in t h e o b s t r u c t i o n ARF and r ema ined unchanged i n t h e G e n t a m i c i n ARF. The h y d r a t i o n f r a c t i o n and t h e f r a c t i o n bound changed s i g n i f i c a n t l y i n a d i r e c t i o n o p p o s i t e to t h a t of the change in t he t o t a l water c o n t e n t .

D i f f e r e n t p r o f i l e s of r e n a l c o r t i c a l and m e d u l l a r y m a g n e t i c resonance p r o p e r t i e s found i n s e v e r a l models of expe r imen ta l ARF in r a t s i n d i c a t e t h a t MR p r o p e r t i e s may p r o v i d e e t i o p a t h o g e n e t i c d i a g n o s t i c p o s s i b i l i t i e s .

A MONTE CARLO MODEL FOR THE ABSORPTION AND FLUX DISTRIBUTIONS OF LIGHT IN

TISSUE C1] G. Adam and B. Wilson

A Monte Car lo computer model was deve loped to s tudy t h e p ropaga t ion of l i g h t in t i s s u e . L igh t a t t e n u a t i o n i s assumed to r e s u l t from a b s o r p t i o n and i s o t r o p i c s c a t t e r i n g . The parameters of t he model a r e a s f o l l o w s . A beam of l i g h t i s in t roduced i n t o a volume of t i s s u e hav ing a b s o r p t i o n and s c a t t e r i n g c o e f f i c i e n t s v^ and p s , r e s p e c t i v e l y . Two g e o m e t r i e s were s t u d i e d . I n the f i r s t , i l l u m i n a t i o n i s by an e x t e r n a l p a r a l l e l beam, and in the second, the l i g h t i s in t roduced v i a an implan ted o p t i c a l f i b e r wi th a g i v e n n u m e r i c a l a p e r t u r e . Each i n c i d e n t pho ton was g e n e r a t e d v i a a random number a l g o r i t h m so as t o p r o d u c e an i n i t i a l u n i f o r m i n t e n s i t y d i s t r i b u t i o n , and the r a y was then " t r a c e d " through the t i s s u e volume. The pa th l e n g t h between s u c c e s s i v e i n t e r a c t i o n s was c a l c u l a t e d as

L = - l n ( R ) / u t

B a r z i l a i H o s p i t a l , Ashkelon O n t a r i o Cancer T r e a t m e n t and R e s e a r c h F o u n d a t i o n , H a m i l t o n , O n t a r i o , Canada

166

where R is a uniformly distributed pseudo-random number between 0 and 1 , and yfc = vA + u is the total attenuation coefficient. This formalism generates an exponential distribution of interaction path lengths.

At the interaction point, the photon was assumed to deposit a fraction, y^Pf o f * t s c u r r e n t w e i g h t , WT i t a s a b s o r b e d e n e r g y , and t o emerge from the i n t e r a c t i o n wi th a new we igh t ing f a c t o r WT i+1 = ( ^ / ^ W T ^ The d i r e c t i o n of t h e s c a t t e r e d p h o t o n was s e l e c t e d from a random d i s t r i b u t i o n such t h a t t he p r o b a b i l i t y per u n i t s o l i d a n g l e was the same in a l l d i r e c t i o n s . A new p a t h l e n g t h was c a l c u l a t e d a s b e f o r e , and t h e r a y t r a c i n g cont inued.

The model was u sed t o p r e d i c t t h e d i s t r i b u t i o n o f a b s o r b e d l i g h t dose in homogeneous t i s s u e s of d i f f e r e n t a b s o r p t i o n / s c a t t e r i n g r a t i o s , for i l l u m i n a t i o n i n b o t h g e o m e t r i e s . The p h o t o n f l u x i n t o o p t i c a l f i b e r s p l a c e d i n t h e t i s s u e s a s d e t e c t o r s was a l s o i n v e s t i g a t e d . In t h i s c o n f i g u r a t i o n a d e t e c t o r f i b e r w i t h a g iven numer i ca l a p e r t u r e was "p laced" i n t h e t i s s u e , and t h e number of p h o t o n s e n t e r i n g i t was c o u n t e d d u r i n g a r u n . The d e t e c t o r s were " p l a c e d " i n t h e t i s s u e i n t h r e e d i f f e r e n t p o s i t i o n s r e l a t i v e t o t h e i n c i d e n t l i g h t . One d e t e c t o r was p l a c e d " l o o k i n g " s t r a i g h t a t the l i g h t source , the second a t r i g h t a n g l e s t o the s o u r c e and t h e t h i r d , " l o o k i n g " away from t h e s o u r c e . I n t h i s way an e s t i m a t e c o u l d be made of t h e r e l a t i v e c o n t r i b u t i o n s o f t h e s c a t t e r e d v e r s u s t h e d i r e c t l i g h t t o t h e a b s o r b e d dose i n t h e t i s s u e . T h i s was e s p e c i a l l y i m p o r t a n t , b e c a u s e i n a c t u a l c l i n i c a l c a s e s , i m p l a n t i n g such d e t e c t o r f i b e r s i s t h e o n l y way t o e s t i m a t e t h e l i g h t i n t e n s i t y a t d i f f e r e n t p o i n t s i n the body.

The r e s u l t s were i n t e r p r e t e d i n r e l a t i o n t o the use of v i s i b l e l i g h t i r r a d i a t i o n for p h o t o - r a d i a t i o n t h e r a p y . REFERENCE: [1] Adam, G. and Wilson, B . , Med. Phys . H), 82H (1983) .

EXPERIMENTAL INVESTIGATION OF THE APPLICATION OF THE HOLMIUM LASER TO SOLID ORGANS

S. G i l e r , I . Kap lan , J . Kagan, H, Lotem, A. Dikman, D. S a g i e and L. A. L e v i n I n o r d e r t o d e t e r m i n e w h e t h e r t h e holmium l a s e r h a s an a d v a n t a g e

o v e r o t h e r l a s e r s used i n s u r g e r y , we embarked on a p r e l i m i n a r y s t u d y of i t s e f f e c t on l i v e r and s p l e e n in r a t s . I t a p p e a r s t h a t , a s e x p e c t e d , the ho lmium l a s e r i s l e s s e f f i c i e n t compared w i t h t h e C0 2 l a s e r and c o m p a r a b l e t o t he Nd:Yag l a s e r a s a p h o t o c o a g u l a t o r . Whether o r n o t t h e holmium l a s e r w i l l p rove advan tageous in humans over the o t h e r two l a s e r s , s t i l l remains to be determined. I t i s p o s s i b l e , however, t h a t s i nce i t can be t r a n s m i t t e d through an o p t i c a l f i b e r , i t w i l l have decided a p p l i c a t i o n s in endoscopy.

B e i l i n s o n Medical Center , P e t a h - T i k v a

167

COPPER VAPOR LASER ^ POSSIBLE CLINICAL APPLICATIONS IN OPHTHALMOLOGY S. Gabay, A.Dikman, D. Sag i e , I . Ben-S i ra and S . Cohen

The c o p p e r v a p o r l a s e r i s a p u l s e d l a s e r w h i c h e m i t s two wave l eng ths : 510 (green) and 578 (yel low) nm. This l a s e r ope ra t e s in the r a n g e o f a few kHz r e p e t i t i o n r a t e , 20 n s p u l s e d u r a t i o n . The two l i n e s a r e w e l l a b s o r b e d b o t h by h e m o g l o b i n and p igment e p i t h e l i u m , b u t no t by x a n t h o p h i l . The high peak power (100 kW) makes the l a s e r i d e a l for c u t t i n g pigmented membranes w i th in the eye. At tenua t ion of the average power w i l l a l l o w i t s use for p h o t o c o a g u l a t i o n in the r e t i n a .

THE INFLUENCE OF NONUNIFORM SPATIAL DISTRIBUTION ON LUNG COUNTING A. Talmor, Y. L a i c h t e r , Y. Ben-Haim and A. Kushelevsky

Lung c o u n t i n g p r o c e d u r e s a r e i n f l u e n c e d by t h e i n t e r - o r g a n d i s t r i b u t i o n . A l t h o u g h t h e s p a t i a l d i s t r i b u t i o n w i t h i n t h e l u n g i s nonuniform, c a l i b r a t i o n s g e n e r a l l y assume a uniform d i s t r i b u t i o n s ince the m a g n i t u d e of n o n u n i f o r m i t i e s i s unknown . I t was p o i n t e d o u t , t h e o r e t i c a l l y [ 1 ] , t h a t " r ea sonab le" nonuniform d i s t r i b u t i o n s could lead to c h a n g e s of 20O~30O? i n t h e c a l i b r a t i o n f a c t o r a s compared t o a un i fo rm d i s t r i b u t i o n . The p u r p o s e of t h i s work was t o show t h a t a nonuni form d i s t r i b u t i o n i s a r e a sonab l e expec ta t ion and to i n d i c a t e , e x p e r i m e n t a l l y , the maximum e r ro r in the i n - v i v o lung count ing c a l i b r a t i o n f a c t o r assuming uniform s p a t i a l d i s t r i b u t i o n . Data from animal s t u d i e s and postmortem lung a n a l y s e s of w o r k e r s , p o t e n t i a l l y e x p o s e d t o p l u t o n i u m a e r o s o l i n d i c a t e [2~5] concen t r a t ion of m a t e r i a l in s u b p l e u r a l r e g i o n s long a f t e r e x p o s u r e . A s e t of measu remen t s for d i f f e r e n t s p a t i a l d i s t r i b u t i o n s of 2 r a d i o n u c l i d e s of low p h o t o n e n e r g y : 2^^Pu(T 7 keV), and 2^1Am(60 keV), were p e r f o r m e d , u s i n g s e a l e d s o u r c e s , w i t h a sys tem b a s e d on an e x t e r n a l Nal-Csl phoswich d e t e c t o r [6 ] and a Lawrence Livermore R e a l i s t i c Phantom.

The r e s u l t s for f i v e extreme s p a t i a l d i s t r i b u t i o n s compared to the uniform d i s t r i b u t i o n a r e shown in Table 6.

Table 6 Lung counting r e s u l t s (?) for d i f f e r e n t s p a t i a l d i s t r i b u t i o n s

Radionucl ide S p a t i a l d i s t r i b u t i o n

Uniform A B C D E 2 3 9 P u 100 322.7 10.8 37.9 13.9 53.8

24lAm 100 279.5 25.1 60.6 1)8.3 -95.5

The m a t e r i a l c o n c e n t r a t e s in the lung: f ront (A), back (B), apex (C), bottom (D), cen te r (E).

— T ; Bei l in son Medical Center , Petah-Tikva Technlon, I s r a e l I n s t i t u t e of Technology, Haifa Ben-Gurion Univers i ty of the Negev, Beer -Sheva

168

I t was concluded t h a t : a) the nonuniform s p a t i a l d i s t r i b u t i o n causes an error in the lung counting

c a l i b r a t i o n factor up to 1000?, compared with uniform d i s t r ibu t ion . b) t h e c a l i b r a t i o n e r r o r d e c r e a s e s s h a r p l y a s t h e r a d i a t i o n e n e r g y

i n c r e a s e s . REFERENCES: [1 ] S w i n t h , K. L. , H a d l e y , R. T. and Rhoads , K., The e f f e c t s o f p l u t o n i u m

r e d i s t r i b u t i o n on l u n g c o u n t i n g , 6 t h I n t e r n a t i o n a l Congress of IRPA, B e r l i n (West) , May 1984.

[2 ] McShane, J . F. , D a g l e , G. E. and P a r k , J . F . , P u l m o n a r y d i s t r i b u t i o n o f i n h a l e d 2 ^ ^ P u 0 2 i n Dogs, 19 A n n u a l Hanfo rd L i f e S c i e n c e s Symposium, Rich land , WA, Oct . 1979, CONF-791002.

[33 R h o a d s , K., Mahaf fey , J . A. and S a n d e r s , C. L., H e a l t h P h y s . i|_2, 645 (1982) .

[4] M c l n r o y , J . F . , Boyd, H. A., S t e w a r t , M. W., E u t s l e r , B. C. and T i e t j e n , G. L., D e t e r m i n a t i o n of p l u t o n i u m i n man, Los Alamos R e p o r t

LA-6313-PR, 1975. [5] N e l s o n , I . C , He id , K. R., Fugua, P. A. and Mahony, T. D., H e a l t h

P h y s . 2_2, 925 ( 1 9 7 2 ) . [6] L a i c h t e r , Y., German, U., Romm, E. a n d W e i s e r , G., NRCN(TN)-075, 1 9 8 4 ,

in Hebrew.

DEVELOPMENT OF A NEW TECHNIQUE FOR PYROGENICITY TESTING D. R i n t l e r

Apyrogen ic i ty i s a s i n e ±ua non c o n d i t i o n for p a r e n t e r a l s o l u t i o n s . The i n j e c t i o n of p y r o g e n i c d r u g s ( i . e . d r u g s c o n t a i n i n g g r a m - n e g a t i v e b a c t e r i a l e n d o t o x i n ) can p r o d u c e h y p o t e n s i o n , f e v e r and i n t r a v a s c u l a r c o a g u l a t i o n of the blood.

The methods for the d e t e c t i o n of g ram-nega t ive b a c t e r i a l endo tox in c u r r e n t l y u s e d a r e t h e r a b b i t t e s t and t h e g e l - c l o t method of Lymulus Amebocyte L y s a t e . The r a b b i t t e s t m o n i t o r s t h e r e c t a l t e m p e r a t u r e of r a b b i t s f o l l o w i n g t h e i n t r a v e n o u s i n j e c t i o n o f t h e t e s t m a t e r i a l . The method i s not compl i ca t ed , however i t r e q u i r e s r i g o r o u s t r e a t m e n t of t h e r a b b i t s and v e r y s t r i c t t e s t c o n d i t i o n s . The g e l - c l o t method i s a s e m i q u a n t i t a t i v e t e s t which r e q u i r e s s e r i a l d i l u t i o n s . The r e s u l t s vary wi th l y s a t e s e n s i t i v i t y .

R e c e n t l y , W h i t t a k e r M.A. B i o p r o d u c t s came o u t w i t h what t h e y c a l l t h e " T h i r d G e n e r a t i o n P y r o g e n T e s t i n g " p r o c e d u r e , which c o n s i s t s of a q u a n t i t a t i v e Chromogenic Limulus Amebocyte Lysa te d e t e r m i n a t i o n . Based on the pub l i shed da t a , we deve loped a v a r i a t i o n of t h i s q u a n t i t a t i v e and ve ry s e n s i t i v e t e s t for d e t e r m i n a t i o n of low l e v e l s of g r am-nega t i ve b a c t e r i a l endotoxin in aqueous s o l u t i o n s for p a r e n t e r a l a d m i n i s t r a t i o n and in o t h e r b i o l o g i c a l f l u i d s . T h i s m e t h o d d e t e c t s t h e e n d o t o x i n s p e c t r o p h o t o m e t r i c a l l y a t 405 nm us ing a c o l o r producing s u b s t r a t e . As t h e absorbance i s p r o p o r t i o n a l t o the amount of endotoxin , the c o n c e n t r a t i o n can be c a l c u l a t e d by means of a s t anda rd c a l i b r a t i o n cu rve . Four d i f f e r e n t

169

c o n c e n t r a t i o n s of endotoxin a re used for p l o t t i n g the ca l i b r a t i on curve. From the absorbance of the measured sample, i t s endotoxin con ten t i s c a l c u l a t e d . Va lues lower than 0.2 EU (endotoxin u n i t s ) a r e cons idered pyrogen free.

We a re now t e s t i n g t h i s new techn ique on our p r o d u c t s s u p p l i e d t o hosp i t a l s . Cross checks with the two current ly used methods showed very good agreement. We consider the use of the Chromogenic Lymulus Anebocyte Lysate t e s t to be very promising for the assurance of apyrogeneicity.

170

DETERMINATION OF PENETRATION DEPTH OF AIRBORNE IODINE ON GRANULAR BEDS UNDER DYNAMIC FLOW CONDITIONS [ 1 ] H. Rotem and Z. A l f a s a i

In t h i s s tudy the a b s o r p t i o n c o n s t a n t s of a d s o r p t i o n beds (gas >-f i l t e r s ) used in the n u c l e a r i n d u s t r y were determined. An expe r imen ta l set-up wa3 developed with the following features : a) highly safe in operation with radioiodine (as t r a c e r ) . b) s table airborne iodine output throughout the run (up to 6 h ) . c) c o n t r o l l e d s t a b l e t e s t c o n d i t i o n s ( s i m u l a t i o n of env i ronmen ta l

conditons). d) v e r s a t i l i t y . e) low cost: u t i l i z a t i o n , as much as poss ible of, "on the shelf" equipment

and mater ia l s . Figure 1 shows the g e n e r a l l ayout of the expe r imen ta l s e t u p . The

major components a re : iodine generator (1); environmental conditioning unit (1H-16); d i lu t ion/mixing t r a in (2, 3, k); adsorbent pack (8).

Fig. 1 Test bench

The a n a l y t i c a l unit cons is t s of a Nal (Tl) wel l - type gamma detector, e l ec t ron i c s and a s ing le channel analyzer. The samples were prepared by a thin layer s l i c e r .

F igure 2 shows t h a t the adsorbed amount in a s l i c e , l o c a t e d a t a distance x from the or igin, i s an exponential function of the distance of


173

the layer from the origin and can be expressed as

Q = Ae~kx (1)

This shows that the only observable step is adsorption and e lu t ion is negligible.

I00

— 10

c '•a ° I

O.I 0 2 4 6 8

Adsorbent depth (mm)

Fig. 2

Iodine on an adsorbent bed

REFERENCE:

[1] A l f a s s i , Z. and Rotem, H., in : Trans. Nucl. Soc. I s r a e l , v o l . 12, 1985, p. 120.

OCCUPATIONAL EXPOSURE TO IONIZING RADIATION IN ISRAEL IN THE YEAR 198*1 S. Malchi, Y. Shamai, M. I s r a e l i and T. Schlesinger

A s t a t i s t i c a l a n a l y s i s of the o c c u p a t i o n a l r a d i a t i o n exposure of 7820 rad ia t ion workers in I s r a e l in the year 1984 was carr ied out using a s p e c i a l l y prepared computer program. The a n a l y s i s r e f e r s to e x t e r n a l , whole-body exposure to penetra t ing ionizing rad ia t ion , including gamma, X-ray and f a s t and the rmal neu t ron r a d i a t i o n , as measured by c o n v e n t i o n a l moni tor ing d e v i c e s ( f i l m badges, TLD badges, t r a c k e tch d e t e c t o r s , e t c . ) worn on the upper part of the body of the worker.

Workers and working places were c l a s s i f i e d into 9 groups according to the type of source and radia t ion exposure t rends. The computer program allowed the c a l c u l a t i o n of the c o l l e c t i v e e f f ec t ive dose equiva lent to a l l workers and the average e f f ec t ive dose equivalent to the above subgroups. The r e s u l t s are shown in Table 1.

The c o l l e c t i v e annual e f fec t ive dose equivalent for the whole group of radia t ion workers analyzed was 1.9 Man-Sievert. Only 9.1 % (710 out of 7820) of a l l workers monitored were exposed to r a d i a t i o n which could be de t ec t ed . The d e t e c t i o n s e n s i t i v i t y was about 0.15 mSv for gamma and X-radia t ion , 0.1 mSv for thermal neutrons and 0.7 mSv for fast neutrons. The r e s u l t s indicate that the exposure is not d i s t r ibu ted uniformly among the d i f f e r e n t working groups. The groups most exposed a re i n d u s t r i a l radiographers, nuclear medicine and cardiology department s ta f f and workers

174

in research inst i tutes . Table 1 also indicates that nuclear medicine staff i s the group tha t has the l a rges t number of exposed workers (28% of those monitored were exposed).

Table 1 Distribution of the annual effective dose equivalent

according to working place

Average annual No. of Exposed workers effective dose workers equivalent (mSv)

No. % of exposed workers

Research institutes (including medical laboratories)

Diagnostic radiology

Dental clinics

Nuclear medicine

Cardiology

Oncology (radiotherapy)

Industry (NDT)

Industry (nuclear gauges)

1353

1798

660

3*»9

922

376

1382

899

118

169

21

97

71

69

83

62

8.7

9.4

3.2

28

8.0

18.4

6.0

6.9

2.5

1.9

1.0

3.4

2.2

1.9

4.1

2.2

Workers exposed beyond the detection limit at least once during the year

The average exposure of a l l working groups was below 5 mSv, the value recommended by the ICRP as the annual dose equivalent limit for members of the public.

GAMMA RADIATION MEASUREMENTS IN ISRAEL B. Ben-Shachar, Y. Laichter, U. German and G. Weiser

The natural background in Israel was measured with LiF:Ti,Mg (TLD-100) and CaF2:Dy (TLD-200) crystals. The measurements were performed at five locations: two at the Mediterranean sea coast (Ashquelon and Netanya), one in the Negev desert (Beer-Sheva), one at an altitude of

175

900 meters ( Je rusa lem) and t h e l a s t a t an a l t i t u d e of 600 meters (Arad) in t h e Negev d e s e r t . F i v e G-1 c a r d s and f i v e G-2 c a r d s were u sed a t each p l a c e . Two of e a c h of t h e c a r d s were" p r e - i r r a d i a t e d t o 5 mGy b e f o r e t h e measurements began and t h e s e ca rds were used for a s s e s s i n g the fading . The n a t u r a l background a t each s t a t i o n was measured for a per iod of 300 days. The c a r d s were changed e v e r y 30 days a t e a c h l o c a t i o n . The t o t a l a n n u a l dose a t sea l e v e l i s about 0.60 mGy, f i t t i n g the r e s u l t s ob ta ined by o t h e r s in Europe and the U.S.A. The n a t u r a l background i n c r e a s e s w i th a l t i t u d e , a s was s e e n from t h e r e s u l t s measured i n J e r u s a l e m (0.83 mGy) and i n Arad (0 .71 mGy).

IMPROVED FADING ESTIMATION IN ENVIRONMENTAL DOSIMETRY WITH CaF2:Tm THERMOLUMINESCENT CARDS

B. Ben-Shachar, Y. L a i c h t e r , U. German and G. Weiser In t h e l a s t d e c a d e , CaF~:Trn (TLD-300) c r y s t a l s h a v e been used i n

fin env i ronmen ta l and pe r sonne l dos imetry . The s e n s i t i v i t y of CaF2:Tm t o Co photons i s h igher than t h a t of LiF by a f a c t o r of ten . I t s glow curve has t h r e e main peaks, the t h i r d one s e p a r a t e d from the f i r s t two, and t h e r e f o r e i t s a r e a can be measu red w i t h h i g h a c c u r a c y . We h a v e m e a s u r e d s e v e r a l p r o p e r t i e s , i .e . r e p r o d u c i b i l i t y , l i n e a r i t y and fading of CaF2:Tm us ing the s t a n d a r d Harshaw G-3 c a r d s , each of which c o n t a i n s two TLD-300 c r y s t a l s . The f a d i n g was found t o be h i g h d u r i n g a month, b u t a p o s t p o n e m e n t o f H days i n r ead ing t h e c a r d s r educes t he u n c e r t a i n t y due t o t h e f ad ing t o l e s s t h a n H%.

THE CHARACTERISTICS OF CaF 2 :Tm CRYSTALS ( T L D - 3 0 0 ) IRRADIATED BY ELECTROMAGNETIC RADIATION [1 ] B. Ben-Shachar, S . Yona, Y. L a i c h t e r , U. German and G. Weiser

The main c h a r a c t e r i s t i c s of t h e CaF2:Tm c r y s t a l s (TLD-300), a s a dos imeter , were measured: t h e glow c u r v e , s e n s i t i v i t y , l i n e a r i t y , fading and energy dependence for photons; and compared t o t hose of LiF (TLD-100) and CaF2:Dy (TLD-200). I t was found t h a t CaF2:Tm can be used fo r env i ronmen ta l dos imetry by r ead ing the c r y s t a l s a f t e r four days. REFERENCE: [ 1 ] B e n - S h a c h a r , B. , Yona, S. , L a i c h t e r , Y., German, U. and W e i s e r , G.,

NRCN-562, in Hebrew.

MEASUREMENT OF SOME PROPERTIES OF LiF AND CaF2:Dy CRYSTALS IRRADIATED BY M0N0ENERGETIC THERMAL NEUTRONS [1] B. Ben-Shachar, U. German and G. Weiser

A few p r o p e r t i e s of LiF and CaF2:Dy c r y s t a l s , i r r a d i a t e d by monoenergetic thermal n e u t r o n s , were measured. I t was found t h a t by us ing a p a i r of TLD-600 and TLD-700 c r y s t a l s , t h e t h e r m a l n e u t r o n dose from a mixed f i e l d of gamma r a y s and thermal n e u t r o n s can be measured. REFERENCE: [ 1 ] Ben-Shachar, B . , German, U. and Weiser , G., NRCN-552, 1985, in Hebrew.

1 76

LOSS AND RECOVERY OF A 10 mCi 6 0 Co INDUSTRIAL SOURCE [ 1 ] Y. Keren, T. S c h l e s i n g e r and M. I s r a e l i

I n O c t o b e r 1985 , a 10 mCi ""Co i n d u s t r i a l s o u r c e was l o s t and r e c o v e r e d . The s o u r c e was p a r t of an i n d u s t r i a l d e n s i t y gauge u s e d i n a f e e d b a c k s y s t e m c o n t r o l l i n g a raw m a t e r i a l f e e d c o n v e y o r . The l o s s was d i s c o v e r e d when t h e m a i n t e n a n c e e n g i n e e r t r i e d t o c a l i b r a t e t h e s y s t e m a f t e r i t was assembled.

An emergency team from t h e R a d i a t i o n S a f e t y D e p a r t m e n t a t S o r e q N u c l e a r R e s e a r c h C e n t e r was c a l l e d i n and, a f t e r a s h o r t i n q u i r y and a r a d i a t i o n s u r v e y , t h e s o u r c e was found i n t h e g r o u n d n e a r t h e g a u g e , and r e c o v e r e d . During the i n q u i r y the fo l lowing f a c t s were r e v e a l e d .

a) Four s i m i l a r d e n s i t y g a u g e s were p u r c h a s e d by t h e f a c t o r y and were assembled, a f t e r a r r i v a l , by a person u n q u a l i f i e d to h a n d l e r a d i o a c t i v e m a t e r i a l s and wi thou t t h e knowledge of t he r a d i a t i o n s a f e t y o f f i c e r of t h e f a c t o r y . The p e r s o n who d i d t h e work d i d n o t u s e a r a d i a t i o n moni tor .

b) During t h e assembly one of the sources was de tached from i t s h o l d e r and f e l l i n t o t h e sand near the machine.

c) The s o u r c e was u n s h i e l d e d fo r a few d a y s , b u t t h e t i m e p e r s o n n e l were exposed t o t he source was s h o r t .

d) The s o u r c e was n o t damaged. A smear t e s t t a k e n a f t e r i t s r e c o v e r y d i d not show any e x t e r n a l con tamina t ion .

e) R e c o n s t r u c t i o n of p e r s o n n e l movements r e s u l t e d in a c a l c u l a t e d maximal dose of about 100 mRem t o t he person exposed to the h i g h e s t dose.

M e a s u r e s f o r p r e v e n t i o n of s i m i l a r i n c i d e n t s i n t h e f u t u r e were o u t l i n e d to t he company. REFERENCE: [1] Keren , Y., S c h l e s i n g e r , T. and I s r a e l i , M., i n : T r a n s . N u c l . Soc .

I s r a e l , v o l . 13 , 1986, p . 192.

RADIOLOGICAL IMPLICATIONS OF USING PH0SPH0GYPSUM AS A BUILDING MATERIAL IN ISRAEL [1 ]

M. Marga l io t , M. I s r a e l i , T. S c h l e s i n g e r , Y. Shamai and 0 . Even Gypsum (CaSOjj.nf^O) i s produced in I s r a e l a t a r a t e of about 100,000

t o n s / y as a b y - p r o d u c t o f t h e p h o s p h a t e i n d u s t r y . R e c e n t l y , a l o c a l m a n u f a c t u r e r s t a r t e d u s i n g t h i s phosphogypsum f o r t h e p r o d u c t i o n of i n t e r n a l p a r t i t i o n s i n b u i l d i n g s . The r a d i o a c t i v i t y i n phosphogypsum ( m a i n l y ^ D R a and i t s p r o g e n y ) p r o d u c t s i s known t o be h i g h e r t h a n normal [ 2 ] .

I n o r d e r t o e s t i m a t e t h e r a d i o l o g i c a l i m p l i c a t i o n s of u s i n g phosphogypsum as a b u i l d i n g m a t e r i a l , the 2 Ra con t en t of 7 phosphogypsum b o a r d s and of 2 n a t u r a l gypsum b o a r d s was measu red . The m e a s u r e m e n t s c o n s i s t e d of c rush ing the boa rds , s e a l i n g them in a i r - t i g h t b o t t l e s for two weeks ( for 2 2 2 Rn b u i l d - u p ) and then de te rmin ing the 2 2 t )Ra con t en t from the i n t e n s i t i e s of the 2 1 l | B i y ~ r a y s (0.61 and 1.76 MeV).

177

A 2 2 &Ra con ten t of 25 + 2.4 pCi /g was found in the phosphogypsum boards, versus 1 pCi/g in na tu ra l gypsum boards. The presence of Ra in the bui ld ing mater ia l has a two-fold r a d i o l o g i c a l s igni f icance: a) The gamma ray exposure r a t e in the building i s elevated. b) Rn i s re leased into the bui lding, exposing the lungs of the res iden ts

to elevated alpha r ad ia t ion l e v e l s . The exposure r a t e in a 3x3x2.5 m room, constructed of phosphogypsum (wal ls o n l y ) , wi th a 2 2 ° R a con ten t of 25 pCi /g , a w a l l d e n s i t y of 0.95 g/cm^, a wal l ha l f - th ickness of 1 cm, was computed (assuming the appropriate s e l f -a b s o r p t i o n c o e f f i c i e n t s ) . R e s u l t s of t h i s computat ion v e r s u s a c t u a l measu remen t i n a 3x3x2.5 nH room ( u s i n g a f l a t r e s p o n s e p l a s t i c s c i n t i l l a t o r - Automess Szintomat 613^A) are p resen ted in Fig. 3. The gamma dose increment r e s u l t i n g from a 100? occupancy of such a room i s thus ( t a k i n g an ave rage exposure r a t e enhancement of 20 uR/h) 175 mRem/y (e f fec t ive dose equiva lent ) .

40

JZ

ce 30

5.

Inte

nsity

0 •

10

—

O

I 50 I0O

Distance from wall (cm) I50

Fig. 3 Exposure rate (in uR/h) in a 3x3x2.5 m' room constructed from phosphogypsum, along the main diagonal (1 m above ground), computed values (continuous line),

experimental values (circles)

For calculating 222Rn, we adopted the Krisiuk equation [3] which relates the 22°Ra content of the walls to the 222Rn concentration in the

P?P room air. From this equation we found that the average c"Rn concentration increment in the air is 0.19 pCi/£. Assuming 0.35 as the equilibrium factor F for 222Rn progeny, we obtain a radon exposure increment of 35 mWLM/y corresponding to 32 mRem/y (effective dose equivalent).

As a result of this work, some changes in the production process were recommended in order to reduce the 22bRa content in the finished product to less than 10 pCi/g, and the exposure increment to less than

178

90 mRem/y (for a 100? occupancy) in accordance with the ICRP recommendation tha t the incremental dose to the population should not exceed 100 mRem/y. REFERENCES: [1] M a r g a l i o t , M., I s r a e l i , M.f S c h l e s i n g e r , T., Shamai, Y. and Even, 0.,

in : Trans. Nucl. Soc. I s r a e l , vol . 13, 1986, p . 176. [2] Nathan, Y. e t a l . , EAEA-SM-208/29, 1976, p . 645-655. [3] Kr i s iuk , Y. e t a l . , A s tudy on r a d i o a c t i v i t y in b u i l d i n g m a t e r i a l s .

Research I n s t i t u t e for Radiation Hygiene, Leningrad (1971).

RECOVERY OF A CONTAMINATED SITE [1] E. Sberlo, Y. Bashary and E. Nairn

In August 1985 a warehouse of the t e x t i l e complex Polgat burned down comple te ly . This warehouse had been p rov ided with 16 smoke d e t e c t o r s

p h i

containing Am sources. For fear of radioactive exposure, our radiation ->hi

safety team was c a l l e d upon to monitor the s i t e , locate the c Am sources, supervise the removal of the debris by a c i v i l works contractor and proceed to f u l l decontamina t ion . A v a r i e t y of means was used for t h i s purpose . The task was completed in 6 days. REFERENCE: [1] S b e r l o , E., Bashary, Y. and Nairn, E., i n : Trans . Nucl . Soc. I s r a e l ,

vol . 13, 1986, p . 186.

EFFECTIVENESS OF PROTECTIVE MEASURES IN REDUCING THE RADIOLOGICAL EFFECTS DUE TO AN ACCIDENT IN A NUCLEAR POWER PLANT J . Koch and J . Tadmor

The s tudy of the e f f e c t i v e n e s s of s h e l t e r i n g ( in c i v i l defense s h e l t e r s , as w e l l a s in r e g u l a r b u i l d i n g s ) in r educ ing the r a d i o l o g i c a l consequences following an atmospheric r ad ioac t i v i t y re lease from a nuclear power plant was continued [ 1 ] . The REMAND consequence model [2] was used to c a l c u l a t e indiv idual and c o l l e c t i v e rad ia t ion doses and hea l th effects for unprotected and shel tered populations. Computations were performed on a r b i t r a r i l y chosen reference cases (PWR1 and PWR3 type accidents) occurring a t a 1 ,000 MWe n u c l e a r power p l a n t , h y p o t h e t i c a l l y l o c a t e d a t d i f f e r e n t s i t e s in I s r a e l .

I t was found (Table 2) tha t she l t e r i ng in c i v i l defense s h e l t e r s or even in regular ( I s r a e l i ) bui ldings is highly e f fec t ive in reducing ear ly f a t a l i t i e s and o ther n o n - s t o c h a s t i c e f f e c t s , and i s l e s s e f f e c t i v e in m i t i g a t i n g s t o c h a s t i c e f f e c t s . The eff ic iency of she l t e r ing i s s t rongly dependent on how soon a f t e r the acc iden t these measures a re taken and t h e r e f o r e the i n s t a l l a t i o n of a f a s t a l a rm system for the p o p u l a t i o n i s j u s t i f i e d .

Large u n c e r t a i n t i e s a re i n v o l v e d in the c a l c u l a t i o n s , due to the uncer ta in t i es in the numerous parameters and assumptions of the consequence model, and due to the question of accep tab i l i t y and a p p l i c a b i l i t y of the p ro tec t ive measures. An uncertainty ana lys i s i s therefore needed to permit

179

Table 2 S h e l t e r i n g e f f e c t i v e n e s s

% r e d u c t i o n i n h e a l t h e f f e c t s by Heal th e f f e c t b u i l d i n g s s h e l t e r s

Ear ly f a t a l i t i e s 98 99 Microcephaly 58 66 Male s t e r i l i t y 100 100

Late f a t a l i t i e s 39 40 Thyroid c a n c e r s 32 32

^Re lea se t y p e : PWR1, 30 min long , 20-l45m e f f e c t i v e r e l e a s e h e i g h t ( a c c o r d i n g t o m e t e o r o l o g i c a l c o n d i t i o n s ) .

M e t e o r o l o g y : p r o b a b i l i s t i c t r e a t m e n t a cco rd ing t o t h e a n n u a l f r e q u e n c i e s o f t h e v a r i o u s combina t ions of a tmospher ic s t a b i l i t y and wind v e l o c i t y .

sound dec is ion-making concerning the use of o f f s i t e p r o t e c t i v e measures and i t i s c u r r e n t l y being under taken .

A s u r v e y of t h e d i f f e r e n t u n c e r t a i n t i e s e x i s t i n g i n t h e compu te r model i s be ing conducted, focusing on the paramete rs and the submodels t h a t i n f l u e n c e the e f f e c t i v e n e s s of p r o t e c t i v e measures (e.g. e f f e c t i v e r e l e a s e h e i g h t , p r o t e c t i o n f a c t o r s ) . The p r o p a g a t i o n of i n p u t u n c e r t a i n t i e s t o ou tpu t u n c e r t a i n t y i s being performed v i a the r e sponse s u r f a c e method [ 3 3 , which i n v o l v e s the f i t t i n g of a r e g r e s s i o n s u r f a c e t o r e p l a c e t he complex o u t p u t f u n c t i o n , and t h e a p p l i c a t i o n o f Monte C a r l o s i m u l a t i o n t o t h e r e s p o n s e sur face . REFERENCES:

[1] Tadmor, J . and Koch, J . , i n : I A - 1 4 1 2 , 1985 , p. 161 . [2] S t e r n , E., C o v a l i u , Z. , Kaufman, J . and S t a r k , M., REMAND - A Computer

Code f o r A s s e s s i n g t h e C o n s e q u e n c e s of an A c c i d e n t i n N u c l e a r Power P l a n t s . Pa r t B - User 's Guide, I s r a e l AEC Report LDI 85~57, 1985.

[33 Commission of t he European Communities, Response Surface Methodology -Handbook for N u c l e a r R e a c t o r S a f e t y , e d i t e d by L. O l i v i , R e p o r t EUR9600EN, 1984.

RECLEAR .- AN EVACUATION SIMULATION MODEL WHICH CALCULATES RADIATION DOSES TO THE EVACUATED POPULATION E. Gants and J . Tadmor

RECLEAR - a s i m u l a t i o n model - was deve loped to c a l c u l a t e p o p u l a t i o n e v a c u a t i o n t i m e s , a s w e l l a s r a d i a t i o n d o s e s c a u s e d t o t h e e v a c u a t e d

180

p o p u l a t i o n , f o l l o w i n g an a c c i d e n t a l a tmospher ic r e l e a s e of r a d i o a c t i v i t y from a n u c l e a r p l a n t [ 1 ] .

The mode l was used t o a s s e s s t h e e v a c u a t i o n e f f i c i e n c y f o r two h y p o t h e t i c a l n u c l e a r power p l a n t s i t e s in I s r a e l . Va r ious pa r ame te r s were i n v e s t i g a t e d , e.g. d i r e c t i o n of e v a c u a t i o n r o u t e , number of l a n e s , type of v e h i c l e s and d e p a r t u r e t ime. The r e s u l t s r e v e a l t h a t e v a c u a t i o n i s h i g h l y e f f e c t i v e i n r educ ing the r a d i o l o g i c a l e f f e c t s f o l l o w i n g an a c c i d e n t in a n u c l e a r power p l a n t . Fo r e x a m p l e , t h e number of e a r l y f a t a l i t i e s i s r e d u c e d by up t o 1 00$ compared w i t h t h a t e n c o u n t e r e d i n an u n p r o t e c t e d s t a t i o n a r y p o p u l a t i o n .

Among t h e e v a c u a t i o n p a r a m e t e r s which were s t u d i e d , p a r a m e t e r s a f f e c t i n g t h e t r a f f i c load and t h e e v a c u a t i o n r o u t e d i r e c t i o n were found to be most e f f e c t i v e i n r e d u c i n g r a d i a t i o n doses and r a d i o l o g i c a l e f f e c t s . T a b l e 3 shows t h e i n f l u e n c e of t h e s e p a r a m e t e r s on t h e e v a c u a t i o n e f f i c i e n c y , as expressed by the r e d u c t i o n in e a r l y f a t a l i t i e s .

Table 3 I n f l u e n c e of evacua t ion p l ann ing paramete rs on evacua t ion e f f i c i e n c y

Case R e l a t i v e pe rcen tage of e a r l y f a t a l i t i e s

Reference case 100 Two l a n e s 72 Evacua t ion by buses 74 P e r p e n d i c u l a r evacua t ion r o u t e 67

One l a n e , evacua t ion by p r i v a t e c a r s , r a d i a l evacua t ion r o u t e

REFERENCE:

[1] G a n t s . E . and Tadmor, J . , i n : IA-1H12, 1985 , p . 159.

THE STUDY OF IMPACTS OF DISASTERS AND THEIR MITIGATION: A SURVEY OF IMPACT ASSESSMENT METHODS AND A PROPOSED QUANTITATIVE METHODOLOGY FOR THE ISRAELI SYSTEM

S. Amir This study considers several quantitative methodologies that may

be effective in assessing the impacts of disasters and the benefits derived

from alternative mitigating measures. The methodologies examined differ in

several respects, such as: how and to what extent they quantify impacts,

how they deal with the spatial and temporal dimensions of impacts, how

various impacts are weighted, how uncertain outcomes are introduced and

compared, and how they refer to the distribution of costs and benefits

among different groups in the population.

The proposed methodology specifically refers to the primary features

of disasters. It is based on principles derived from the general theory of

181

s y s t e m s a n a l y s i s . The i m p a c t s of d i s a s t e r s a r e t r a c e d d y n a m i c a l l y and q u a n t i t a t i v e l y u s i n g sys tems models . The proposed methodology i s unique i n d e f i n i n g a space for the system d e s c r i p t o r s t h a t i n c l u d e s b o t h e x t e n s i v e and i n t e n s i v e s t a t e v a r i a b l e s . The i n t e n s i v e v a r i a b l e s q u a n t i f y t y p i c a l c h a r a c t e r i s t i c s of t h e s t a t e o c c u p i e d by t h e s y s t e m . They a r e used t o weigh m a t e r i a l f lows which a r e d e s c r i b e d by t h e e x t e n s i v e v a r i a b l e s .

The s t u d y p r e s e n t s s e v e r a l s y s t e m i c m o d e l s , e a c h s i m u l a t i n g t h e dynamic b e h a v i o r assumed by a d i f f e r e n t component of the I s r a e l i system; e.g., i t s human, economic and n a t u r a l r e s o u r c e s .

MEASURES TO CURB S02 EMISSIONS FROM THE ESHROL POWER PLANT: COST AND EFFECT ON S02 AMBIENT CONCENTRATIONS IN THE ASHDOD REGION S. Amir

In t h i s s tudy t h e c o s t s and b e n e f i t s of measures i n s t a l l e d t o curb S02 emiss ions from p o l l u t i n g s o u r c e s i n t h e Ashdod r e g i o n were examined. 3 e n e f i t s of each measure were a s s e s s e d through i t s expected e f f e c t on the d e n s i t y d i s t r i b u t i o n f u n c t i o n of SO,, amb ien t c o n c e n t r a t i o n i n t h e a r e a . Data g l e a n e d over 13 y e a r s of m o n i t o r i n g were examined and t h e e f f e c t s on s e v e r a l pr imary pa rame te r s of t h e r e s u l t i n g d i s t r i b u t i o n s were es t ima ted . Among t h e s e p a r a m e t e r s a r e : e x t r e m e v a l u e s of t h e d i s t r i b u t i o n , p r o b a b i l i t i e s of exceeding extreme v a l u e s , the number of days and months per year i n which extreme v a l u e s a r e expected, t he mean and v a r i a n c e of the d i s t r i b u t i o n . The r e s u l t i n g a n a l y s i s enab led u s t o e v a l u a t e t he economic s i g n i f i c a n c e of p o s s i b l e m o d i f i c a t i o n s o f t h e S 0 2 a i r q u a l i t y ambien t s t a n d a r d s in I s r a e l .

ANALYSIS OF POLLUTION DISPERSION FROM PAMA'S DEMONSTRATION PLANT FOR THE ENVIRONMENTAL IMPACT STATEMENT

D. S k i b i n , M. Calaf and H. Ohaion The c o n s t r u c t i o n p l a n s for PAMA's demons t ra t ion p l a n t were examined

in the framework of p r e p a r i n g the Envi ronmenta l Impact S ta tement . The main s o u r c e f o r g a s e o u s a i r p o l l u t i o n was i d e n t i f i e d as t h e b u r n e r s t a c k . A haza rds e v a l u a t i o n method was d e v e l o p e d , based on t h e normal i zed i n t e g r a t e d c o n c e n t r a t i o n c o n c e p t . An i n t e r a c t i v e computer program was prepared for c a l c u l a t i n g t h e c o n c e n t r a t i o n s of p o l l u t a n t s e m i t t e d from t h e s t a c k a t v a r i o u s d i s t a n c e s from the s t a c k , under va r ious m e t e o r o l o g i c a l c o n d i t i o n s .

At f i r s t we r e c o m m e n d e d , a c c o r d i n g t o t h e r e s u l t s o f t h e c a l c u l a t i o n s , t h e b u i l d i n g of a h i g h s t a c k . In a d d i t i o n , we s u g g e s t e d l o w e r i n g t h e r e t o r t b u i l d i n g and c h a n g i n g t h e p o s i t i o n o f t h e s t a c k r e l a t i v e to i t . T h i s r e c o m m e n d a t i o n was a c c e p t e d and t h u s p e r m i t t e d lower ing t h e s t a c k by t e n me te r s . I t was recommended t o p l a n and b u i l d the s t a c k so t h a t i t s d iameter w i l l be t h e minimum p o s s i b l e .

We recommended e r e c t i n g a s t a c k t h a t w i l l be H m t a l l e r t h a n t h e r e t o r t b u i l d i n g , i . e . -16 m h i g h . Th i s w i l l e n s u r e t h a t p o l l u t i o n c o n c e n t r a t i o n around PAMA, under a l l m e t e o r o l o g i c a l c o n d i t i o n s , w i l l not exceed h a l f t h e I s r a e l i a i r q u a l i t y s t anda rd for 99? of t he t ime. I t w i l l

1 82

a l s o ensure t h a t no aerodynamic, topograph ic or b u i l d i n g e f f e c t s w i l l cause v i o l a t i o n of t h e s e s t a n d a r d s .

P rov ided t h a t t he p l a n t w i l l be p lanned so t h a t emiss ions from the s t a c k could be s topped w i t h i n an hour , in case of bu rne r f a i l u r e , and t h a t no more t h a n s e v e r a l f a i l u r e s p e r y e a r w i l l o c c u r , n o n - v i o l a t i o n o f t h e s t a n d a r d s i s guaran teed a l s o i n ca se of f a i l u r e s .

Coincidence of the p o l l u t i o n plumes from PAMA and Rotem F e r t i l i z e r s was a l s o examined. Peak c o n c e n t r a t i o n s w i l l be ob t a ined o u t s i d e t he ARAD complex fence. They w i l l no t exceed the I s r a e l i s t a n d a r d for 100% of t he time- PAMA's c o n t r i b u t i o n w i l l be l e s s than 20?. Exposure of d r i v e r s and highway t r a v e l e r s a r o u n d FAMA was a l s o c o n s i d e r e d . No v i o l a t i o n of t h e s t a n d a r d s i s expec ted .

The p r e s e n t haza rds e v a l u a t i o n i s c a r e f u l and c o n s e r v a t i v e , bu t i t s i m u l t a n e o u s l y ach i eved c o n s i d e r a b l e s a v i n g s by p e r m i t t i n g a d e c r e a s e i n the planned s t a c k h e i g h t by - 2 0 ? .

COULD THE VERTICAL VELOCITY EXPLAIN DISCREPANCY BETWEEN THEORY AND MEASUREMENTS OF AIR P0LLUTI0N?+ [ 1 ]

D. Sk ib in , J . C. Kaimal and J . E. Gaynor The v e r t i c a l v e l o c i t y (w) in the p l a n e t a r y boundary l a y e r (PBL) i s

10HO0 t i m e s s m a l l e r t h a n t h e h o r i z o n t a l wind s p e e d . The d i f f i c u l t y i n m e a s u r i n g w can be o v e r c o m e u s i n g t h e p r e s e n t g e n e r a t i o n s e n s i t i v e equipment e.g. s o n i c , ho t wi re , ho t f i l m anemometers, e t c . N e v e r t h e l e s s , though wide ly used in t he l a s t two decades, r e l i a b l e , r e p r e s e n t a t i v e l ong t e rm m e a s u r e m e n t s of w c a n n o t be found i n t h e l i t e r a t u r e . I n o r d e r t o compute momentum and h e a t f l u x e s , t h e a v e r a g e v e r t i c a l v e l o c i t y w i s u s u a l l y computed, s u b s t r a c t e d and no t r e p o r t e d .

Data from the e i g h t son ic anemometers mounted on the 300 m BA0 tower were ana lyzed . The v e r t i c a l v e l o c i t y was found t o be n e g a t i v e l y b i a s e d and to depend upon t h e t e m p e r a t u r e , wind d i r e c t i o n and s p e e d . The a n a l y s i s showed t h a t , be ing very s e n s i t i v e equipment, even i n f l u e n c e s cons ide red t o be n e g l i g i b l e a r e i m p o r t a n t when one w i s h e s t o m e a s u r e w w i t h -1 cm/s a c c u r a c y . Even s m a l l i n s t r u m e n t s p o s i t i o n e d downwind o f t h e m e a s u r i n g s enso r s , and s m a l l topography s l o p e s ~100m below, can s i g n i f i c a n t l y a f f e c t w. Appropr ia te c o r r e c t i o n s were found and a p p l i e d , g i v i n g W with ~1 cm/s accuracy. We a r e now a b l e t o show t h a t s i g n i f i c a n t v e r t i c a l v e l o c i t i e s , of t h e o r d e r -10 c m / s , a r e p r e s e n t most of t h e t i m e , f o r a v e r a g i n g t i m e s of -20 minutes , a t 10 me te r s and h ighe r above the ground [ 2 ] .

This f a c t has a tremendous i n f l u e n c e on t h e p o l l u t i o n c o n c e n t r a t i o n f i e l d c l o s e t o t h e g r o u n d . An a v e r a g e w of 10 c m / s , p e r s i s t i n g f o r 20 minutes , w i l l i n c r e a s e or decrease , t h e p o l l u t i o n plume a x i s by -120 me te r s .

+This work was performed a t N0AA/WPL, Boulder , CO, U.S.A. *NOAA/WPL, Boulder , CO, U.S.A.

183

Such c h a n g e s may d r a s t i c a l l y a l t e r t h e p r e d i c t e d g round l e v e l concentrations. This effect w i l l be e s p e c i a l l y pronounced under s t a b l e s t r a t i f i c a t i o n , when the po l lu t i on clouds are narrow and concentrated. We argue t h a t even s m a l l e r w v a l u e s , of the o rde r of a few cm/s, a r e suff ic ient to explain the factor of 2-10 discrepancy (and more) between the predic t ions and the r e s u l t s of the measurements of p o l l u t i o n concentrations in numerous d i s p e r s i o n exper iments . The i m p l i c a t i o n s of t h e s e f i nd ings were considered. REFERENCES: [1] Sk ib in , D., Kaimal, J . C. and Gaynor, J . E., in : 7 th Symposium on

Turbulence and Diffusion, November 1985, Boulder, CO, U.S.A., American Meteorological Society, p. 11-13.

[2] Sk ib in , D., Kaimal, J . C and Gaynor, J. E., J . Atmos. Oceanic Techno 1.

2, 598 (1985).

QUANTITATIVE AND QUALITATIVE ASPECTS OF THE RECENT CLIMATIC FLUCTUATIONS [1]

H. L. Striem

Systematic observations of p rec ip i t a t ion , temperature and barometric pressure have been made in Jerusalem since the middle of the 19th century, and these c o n s t i t u t e the l o n g e s t r ecord of c l i m a t i c parameters i n the Middle East. The mean monthly values were published in the World Weather Records [2] and served as a basis for the various c l imat ic inves t iga t ions by the author.

The f l u c t u a t i o n s which have l a t e l y a f f ec t ed the c l i m a t e in our region are of two kinds:

( i ) Q u a n t i t a t i v e changes i n t h e p a r a m e t e r s , e .g . , h i g h e r temperatures and l e s s ra in in winter, or higher barometric pressure.

( i i ) Q u a l i t a t i v e changes in the regime by s h i f t s in t h e t imes of occurrence, e.g., the maxima or minima tend nowadays to occur l a t e r in the calendar year.

When considering averages for c l imat ic parameters for periods which c o n s t i t u t e a s i g n i f i c a n t f r a c t i o n ( 1 / 3 - 1 / 2 ) of the t o t a l l eng th of t h e o b s e r v a t i o n a l r eco rd , the dominant q u a n t i t a t i v e r e c e n t changes in the climate were:

( i ) The win te r (Dec.-March) t empera tu res r o s e by more than 1 °C, whi le the summer (June-Sept . ) t empera tu res remained s t eady during the period of observations [ 3 . 4 ] .

( i i ) The mean monthly barometric pressure rose by about 1 mb [ 5 ] . ( i i i ) The annual r a i n f a l l decreased from about 600 mm in the second

hal f of the 19th century to about 500 mm in the f i r s t ha l f of t h i s century, and there is at present a trend of increased r a i n f a l l [4 ,6] .

The q u a l i t a t i v e change in the c l i m a t i c regime i s expressed i n a change in the t imes of occurrence of the extrema of mean monthly v a l u e s , mostly thei r re ta rda t ion .

( i ) The maximum in mean monthly t empera tu re occurs in summer nowadays about one t h i r d of a month l a t e r ( i n the l a s t cen tu ry 68? of the

184

ANNUAL RAINFALL

1860 1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970

e l i l t H1IIUR MAXIMUM OF BAROMETRIC PRESSURE MEAN DECENNIAL VALUES

Fig. JJ

The chronological sequence of climatic parameters in Jerusalem.

Mean decadal values.

maxima occurred in August and later, versus 76? in the first half of this

century; and the occurrence of the maximum in July or earlier, decreased

from 28? to 21?).

(ii) There is also a retardation in the regime of barometric

pressure: the occurrence of the minimum of mean monthly pressure, which

was mainly (68?) in July in the second half of the previous century,

decreased to less than 50? in the middle of this century.

Regarding the pressure maximum, that which used to occur before

November decreased from It? (1861-1885)to 17? (1946-1970), and its

occurrence in November became more frequent (an increase from 21? to 16?).

The retardation in the occurrence of the barometric pressure maximum is

characteristic of drought years [5].

(iii) There was also a change in the occurrence of the rainiest

month. During the first half of this century the highest monthly

1 85

p r e c i p i t a t i o n d u r i n g a w i n t e r o c c u r r e d on four o c c a s i o n s a s e a r l y a s November , s o m e t h i n g wh ich n e v e r h a p p e n e d i n t h e s e c o n d h a l f o f t h e l a s t cen tu ry . As a r u l e , however, the h i g h e s t monthly p r e c i p i t a t i o n i s nowadays r e t a r d e d , i t s occur rence in February or l a t e r has become more f r equen t (43$ in t h i s cen tu ry v e r s u s 37% in the l a s t ) .

The c l i m a t i c f l u c t u a t i o n can be i l l u s t r a t e d (Fig. 4) by t he graph of t h e t i m e s e r i e s of t h e p a r a m e t e r s , where t h e means fo r t h e d e c a d e s h a v e a l s o been marked and j o i n e d up, f o r t h e t h r e e p a r a m e t e r s d i s c u s s e d : t h e annua l r a i n f a l l , t h e maximum of the mean monthly ba rome t r i c p r e s s u r e and the mean s e a s o n a l ( w i n t e r : December to March) t empera tu re ( the two l a t t e r pa ramete r s a r e n e g a t i v e l y c o r r e l a t e d wi th r a i n f a l l C3.7L

The r i s e s and f a l l s in the t h r e e r e s u l t i n g c u r v e s a r e in very c l o s e agreement, and may be cons ide red a r e l i a b l e r e p r e s e n t a t i o n of t he c l i m a t i c f l u c t u a t i o n s a f f e c t i n g Je rusa lem. REFERENCES:

[ 1 ] S t r i em, H. L . , I s r . J . E a r t h - S c i . 3_4, 47 (1985) . [ 2 ] World Weather Records (1951-60), Vol . 2, Europe, US Dept. of Commerce,

Envi ronmenta l Sc i ence S e r v i c e Admin i s t r a t i on , Washington, DC, 1966. [33 S t r i e m , H. L . , I s r . J . E a r t h - S c i . 23 , 55 (1974) . [ 4 ] S t r i e m , H. L., Arch. M e t e o r o l . Geophys. B i o k l i m a t o l . S e r . B ^ 9 , 357

(1981) . [ 5 ] S t r i em, H. L . , I s r . J . E a r t h - S c i . .26, 24 (1977) . [ 6 ] S t r i e m , H. L . , I s r . J . E a r t h ^ S c i . J_6, 22 (1967) . [73 S t r i e m , H. L . , C l i m a t i c Change 2 , 69 (1979) .

EVALUATING WATER RESOURCES IN THE LIGHT OF CLIMATIC FLUCTUATIONS IN ISRAEL [1 ] H. L. S t r i e m

The c l i m a t i c f l u c t u a t i o n s i n I s r a e l , a s shown by t h e 1 2 0 - y e a r r e c o r d s for Je rusa lem, a r e c l e a r l y i l l u s t r a t e d by the correspondence of the u p s ^ a n d - d o w n s of d e c e n n i a l means fo r a n n u a l p r e c i p i t a t i o n , w i n t e r t e m p e r a t u r e s and t h e maxima of b a r o m e t r i c p r e s s u r e ( t h e two l a t t e r in n e g a t i v e c o r r e l a t i o n ) . The f l u c t u a t i o n s occur in an i r r e g u l a r p a t t e r n , the minimal c y c l e of which i s a t l e a s t 20 y e a r s . The long - t e rm ave rage for the range between decada l maxima and minima i s l e s s than h a l f t h e range of the known e x t r e m e s . A band a t +215 mm d i s t a n c e from t h e c u r v e j o i n i n g d e c e n n i a l means w i l l e n v e l o p 90? of a l l c a s e s of t h e a n n u a l r a i n f a l l s e r i e s , and i t s ups-and-downs show the v a l i d i t y of the a b s t r a c t i o n of wet and dry subper iods . Hence the frequency d i s t r i b u t i o n of annual r a i n f a l l s w i t h i n t h e subper iod l e a d i n g up to t he p r e s e n t i s a much b e t t e r guide t o an e x t r a p o l a t i o n fo r t h e oncoming, s a y , f i v e y e a r s , t h a n t h e l o n g - t e r m d i s t r i b u t i o n . The u n c e r t a i n t i e s of the e x t r a p o l a t i o n were e v a l u a t e d . REFERENCE:

[1 ] S t r i e m , H. L., S c i e n t i f i c B a s i s f o r Water R e s o u r c e s Management ( P r o c e e d i n g s of t h e J e r u s a l e m Symposium, S e p t e m b e r 1985) , IAHS P u b l . No. 153, 1985, p. 4 1 1 .

186

IMAGING PROPERTIES OF A CONVEX SPHERICAL SURFACE EMITTING A SPACE CHARGE LIMITED ION CURRENT

I . Chavet The t r a j e c t o r i e s of i o n s e m i t t e d u n d e r s p a c e c h a r g e l i m i t e d

c o n d i t i o n s by a s p h e r i c a l convex su r face of r a d i u s rQ d i s t a n t by dfrom the a c c e l e r a t i o n e l e c t r o d e were s t u d i e d n u m e r i c a l l y by a s t e p - b y - s t e p procedure . The t r a j e c t o r y depends on the r a t i o < ^ / r , on the r a t i o <o of the i n i t i a l t o f i n a l e n e r g y of t h e ion and on t h e emergence a n g l e aQ. The t r a j e c t o r i e s emi t t ed from a s i n g l e po in t on t he emission s u r f a c e determine an image-point behind t h i s s u r f a c e . The p o s i t i o n and a b e r r a t i o n s of t h i s i m a g e - p o i n t were c a l c u l a t e d f o r t h e f o l l o w i n g r a n g e s : 0.1 „< d/v 4 1. 10" 7 « u ^ 10~ 3 and 0 ° « a 0 •£ 89°. The v i r t u a l e m i t t i n g s u r f a c e of minimal width i s s i t u a t e d a t the c u r v a t u r e cen te r and i t s width was determined for the ranges of d/rQ and w mentioned.

ENHANCED ADHESION OF THIN FILMS BY THE ION MIXING FACILITY IN THE ELECTROMAGNETIC ISOTOPE SEPARATOR, MEIRA I . Chavet and G. Lempert

The MEIRA e l e c t r o m a g n e t i c i so tope s e p a r a t o r has been e x p l o i t e d in r e c e n t yea r s as an a c c e l e r a t o r for i m p l a n t i n g n i t r o g e n ions i n t o v a r i o u s s t e e l and t u n g s t e n c a r b i d e t o o l s , on an e x p e r i m e n t a l b a s i s , i n o r d e r t o a s s e s s t h e i m p r o v e m e n t t h u s a c h i e v e d on t h e i r s u r f a c e m e c h a n i c a l p r o p e r t i e s [1 ] .

A l t h o u g h d i r e c t ion i m p l a n t a t i o n h a s s e v e r a l d i s t i n c t advan tages o v e r o t h e r s u r f a c e t r e a t m e n t t e c h n i q u e s , one of i t s l i m i t a t i o n s i s t h e s p u t t e r l i m i t of t h e maximum s u r f a c e c o n c e n t r a t i o n of t h e i m p l a n t e d s p e c i e s , u s u a l l y of t h e o r d e r of t e n s of a p e r c e n t , a t t h e s u r f a c e . T h i s l i m i t a t i o n can be overcome by the technique of ion-mixing, whereby an ion beam i s used to t r a n s f e r e n e r g y t o t h e a toms a t t h e i n t e r f a c e of a t h i n f i l m on a s u b s t r a t e . The t r a n s f e r r e d energy r e s u l t s in the mixing of a few a t o m i c l a y e r s of t h e f i l m and s u b s t r a t e a t t h e i r i n t e r f a c e . T h i s m i x i n g of ten r e s u l t s in e x c e l l e n t adhesion, where o t h e r c o a t i n g t e c h n i q u e s have f a i l e d . In a d d i t i o n t o t h e ion beam e n h a n c e d a d h e s i o n , 100% s u r f a c e c o n c e n t r a t i o n of t h e t h i n f i l m c o a t i n g r e m a i n s on t h e s u r f a c e . By s u c h means , m e t a l c o a t i n g s h a v e been s u c c e s s f u l l y d i r e c t l y a d h e r e d t o ceramics [ 2 ] and g l a s s e s [ 3 ] , as w e l l as t o o t h e r m e t a l l i c s u b s t r a t e s .

If r e a c t i v e ion s p e c i e s a r e employed, in a d d i t i o n to the t r a n s f e r of e n e r g y and r e s u l t i n g e n h a n c e d b i n d i n g , c h e m i c a l r e a c t i o n s may r e s u l t i n compound c o a t i n g s on t h e s u r f a c e . T h i s t e c h n i q u e i s b e g i n n i n g t o be e v a l u a t e d to produce very hard ceramic c o a t i n g s on m e t a l s . Examples which have been demonstrated i n c l u d e imp lan t ing n i t r o g e n i n t o t i t a n i u m f i l m s t o produce t i t a n i u m n i t r i d e [4] and imp lan t ing n i t r o g e n i n t o boron f i l m s t o produce a c o a t i n g c o n t a i n i n g cubic boron n i t r i d e [ 5 ] .

To p r o v i d e the f a c i l i t y for ion-mixing in the MEIRA s e p a r a t o r , t he l a r g e c o l l e c t o r chamber was modified to a l l o w e v a p o r a t i o n of t h i n f i l m s

189

without in te r fe r ing with the ion implantation process. The r a t e of film growth and i t s f i n a l t h i c k n e s s a re c o n t r o l l e d by a quar t z t h i c k n e s s monitor. The maximal thickness which can be achieved in a s ing le operation i s about 0.1 m. Appropr ia te e l e c t r o d e s a re f i t t e d to a l l o w c l e a n i n g of the s u b s t r a t e before the e v a p o r a t i o n by a glow d i s c h a r g e of about 100mA, 3500 V. REFERENCES: [1] Lempert, C, Chavet, I . , Melnick, M., T s a i d i , ¥., in : IA-1412, 1985,

p. 79. [2] Bag l i n , J . E. E. and C l a r k , G. J . , Nucl . Ins t rum. Methods 137/8 , 881

(1985). [3] C o l l i n s , L. E., P e r k i n s , J . C , S t roud , P. T., Thin S o l i d Fi lms jt, M

(1969). [4] Kant, R. A., S a r t w e l l , B. D.f S inger , I . L. and Vardiman, R. C , Nucl .

Instrum. Methods B7/8, 915 (1985). [5] Saton, M. and Fujmoto, F . , Jpn. J . Appl. Phys. 22, L171 (1983).

A NEW ION SOURCE FOR SEPARATION OF RARE-EARTH ISOTOPES E. Hevron and G. Engler

A new surface ionizat ion, integrated ta rge t - ion source was developed for the Soreq on- l ine isotope separator (SOLIS) in an ef for t to extend the

Acceleration power supply

•" 50 kV

,J

Electron bombardment power supply

I kV, IA

Extraction power supply

!5kV

Support structure_ (Tantalum)

Filament support. (Tungsten)

Filament • (Tantalum)

Insulation (Boron nitrate)

Filament power supply

30 V, 40 A

Entrar-ie electrode (Tantalum)

Support structure ' (Molybdenum)

Heat-shield '(Tantalum)

Ig Z 3 5 U onpyrolytic graphite leaves

-Rhenium foil -ZrC cathode - Focusing electrode

(Molybdenum)

j ) Extraction electrode (stainless steel)

Fig. 1

Schematic diagram of the new ion source for the SOLIS

190

r a n g e of i s o t o p e s t h a t can be e x t r a c t e d . The aim i s t o measu re y i e l d s of r a r ° e a r t h e l e m e n t s i n t h e t h e r m a l f i s s i o n of U-235. Due t o t h e i r low f i s s i o n y i e l d s , s l o w d i f f u s i o n r a t e s i n t h e t a r g e t m a t e r i a l , and h i g h i o n i z a t i o n p o t e n t i a l s , measurements of t he se i s o t o p e s a r e d i f f i c u l t .

To ove rcome t h e s e d i f f i c u l t i e s , t h e new s o u r c e was d e s i g n e d t o o p e r a t e a t t empera tu res c l o s e to 2400°C. To enhance d i f f u s i o n , p y r o l y t i c ( l a y e r e d ) g r a p h i t e s h e e t s h a v e r e p l a c e d the amorphous g r a p h i t e s h e e t s of p r e v i o u s des igns [ 1 ] . The new source is shown s c h e m a t i c a l l y in F ig . 1. A major f e a t u r e i s t h e i o n i z a t i o n a r r a n g e m e n t . An i n c a n d e s c e n t r h e n i u m shee t , on which su r f ace i o n i z a t i o n t akes p l a c e , i s enc lo sed in a t a n t a l u m c a v i t y wi th a s m a l l emiss ion o r i f i c e . This c o n s t r u c t i o n i s very e f f i c i e n t compared wi th s u r f a c e i o n i z a t i o n on an open hot s u r f a c e [ 2 ] . REFERENCES: [1] Shmid, M., N i r - E l , Y., E n g l e r , G. and A m i e l , S. , N u c l . I n s t r u m .

Methods JjUl, 601 (1977) . [2 ] Muyse, M., Nucl . Ins t rum. Methods 215, 1 (1983).

DESIGN OF A HIGH EFFICIENCY NEUTRON SPECTROMETER FOR NEUTRON MULTIPLICATION REACTIONS

U. German and G. Shani In the p r e s e n t work a neut ron spec t rometer was deve loped which can

be used t o measure d i r e c t l y t he neutron energy s p e c t r a of up to 3 neu t rons emi t ted s i m u l t a n e o u s l y from a n u c l e a r r e a c t i o n . The spec t rome te r i s based on an NE-213 o r g a n i c s c i n t i l l a t o r and c o v e r s the energy range from 0 t o 1 -4 MeV. The s p e c t r o m e t e r was d e s i g n e d i n an a n n u l a r form c o n s i s t i n g of 3 s e c t i o n s . A s a m p l e can be p l a c e d in i t s c e n t e r where i t can be i r r a d i a t e d by a c o l lima ted neut ron beam which does not i n t e r a c t wi th the s p e c t r o m e t e r . Only t h e s e c o n d a r y n e u t r o n s e m i t t e d from t h e s a m p l e a r e d e t e c t e d .

The o p t i m a l dimensions of the system and the spectromet/ jr response f u n c t i o n s were d e t e r m i n e d w i t h a Monte C a r l o compu te r code . The b a s i c v e r s i o n of t h e code u s e d , 05S, was expanded and t h e geome t ry s u b r o u t i n e s were r e p l a c e d t o f i t t h e c o n f i g u r a t i o n of t he s p e c t r o m e t e r . The s o u r c e geometry was a l s o expanded by adding an i s o t r o p i c neut ron source o p t i o n to the e x i s t i n g ones for p a r a l l e l beams. The op t imal c a l c u l a t e d dimensions were found t o be a b o u t 10 cm l e n g t h and 20-30 cm o u t e r d i a m e t e r fo r a 6.8 cm diameter c e n t r a l h o l e . The spec t romete r was b u i l t and t e s t e d employing PSD e l e c t r o n i c s . The p u l s e he igh t d i s t r i b u t i o n s were ana lyzed u s i n g the FORIST code , t h e r e s p o n s e m a t r i x of which was a l s o c a l c u l a t e d by t h e expanded 05S code.


191

ELECTRODYNAMIC THERMOGRAVI METRIC ANALYZER: I . THE POSITION CONTROL SYSTEM R. E. S p j u t , E. Ba r -Z iv , A. F. Sarofim and J . P. Longwell

The d e s i g n and o p e r a t i o n of a new d e v i c e f o r s t u d y i n g s i n g l e -a e r o s o l - p a r t i c l e k i n e t i c s a t e l e v a t e d t e m p e r a t u r e s , t h e e l e c t r o d y n a m i c t h e r m o g r a v i m e t r i c a n a l y z e r (EDTGA), was examined t h e o r e t i c a l l y and e x p e r i m e n t a l l y . The completed d e v i c e c o n s i s t s of an e l ec t rodynamic b a l a n c e modified to permit p a r t i c l e h e a t i n g by a CO., l a s e r , t empera ture measurement by a t h r e e - c o l o r i n f r a r e d pyrometry system, and con t inuous weighing by a p o s i t i o n c o n t r o l s y s t e m . I n t h i s work t h e p o s i t i o n - c o n t r o l s y s t e m and p a r t i c l e weight measurement were examined.

ELECTRODYNAMIC THERMOGRAVIMETRIC ANALYZER: I I . LASER HEATING AND TEMPERATURE MEASUREMENT

R. E. S p j u t * , E. Ba r -Z iv , A. F. Sarofim* and J . P . Longwell Laser h e a t i n g and t empera tu re measurement of 10 urn to 100 um s i n g l e -

a e r o s o l p a r t i c l e s in an e l ec t rodynamic t he rmograv ime t r i c a n a l y z e r (EDTGA) were e v a l u a t e d t h e o r e t i c a l l y and e x p e r i m e n t a l l y . I n t e r n a l g r a d i e n t s a r e u n i m p o r t a n t i n most c a s e s . T r a n s i e n t h e a t i n g t i m e s r a n g e from 0.1 ms t o 50 ms. The a c c u r a c y and speed of r e s p o n s e of t h e t w o - c o l o r p y r o m e t r y system was e v a l u a t e d . T r a n s i e n t d e t e c t o r r e sponses must be two o r d e r s of m a g n i t u d e f a s t e r t h a n t h e p a r t i c l e t r a n s i e n t s t o e n s u r e a c c u r a t e measurements.

IMPROVED ANALYTICAL PERFORMANCE IN MULTICHANNEL ATOMIC EMISSION SPECTROMETRY BY GENERALIZED INTERNAL REFERENCE PROCEDURES

A. Lorber and Z. Goldbar t I n t e r n a l r e f e r e n c e methods (IRM) a r e wide ly employed for c o r r e c t i n g

non-random f l u c t u a t i o n s in m u l t i c h a n n e l a n a l y s i s . The a p p l i c a b i l i t y of IRM i s l i m i t e d , h o w e v e r , by t h e need t o f i n d a r e f e r e n c e c h a n n e l t h a t mimics the f l u c t u a t i o n s of t he a n a l y t i c a l s i g n a l s . In a p r e v i o u s I n v e s t i g a t i o n [ 1 , 2 ] we desc r ibed a g e n e r a l i z e d i n t e r n a l r e f e r e n c e method (GIRM), for the compensation of non-random f l u c t u a t i o n s in a n a l y t i c a l channe l s r e g a r d l e s s of the parameters a f f e c t i n g them. However, implementa t ion of the GIRM to " r e a l t ime" a n a l y t i c a l systems n e c e s s i t a t e s c o n s i d e r a b l e computat ion t ime (20 s on a D i g i t a l PDP 11 /34 minicomputer, for a s i n g l e measurement) which cannot be met by l a b o r a t o r y computers .

A new mathemat ica l t echn ique based on f a c t o r a n a l y s i s t h a t pe rmi t s computat ion of t he GIRM in " r e a l - t ? ,ie" was deve loped . An e v a l u a t i o n us ing the JY48 d i r e c t r e a d i n g spec t romete r wi th i n d u c t i v e l y coupled plasma (ICP) shows t h a t t h e t e c h n i q u e (a) e l i m i n a t e s non-random n o i s e from a n a l y t i c a l s i g n a l s , (b) a l l o w s c h a r a c t e r i z a t i o n of low and very low frequency n o i s e , and (c) pe rmi t s a c c u r a t e background s u b t r a c t i o n .

Massachuse t t s I n s t i t u t e of Technology, Cambridge, MA, U.S.A.

1 92

A p p l i c a t i o n s of the t echn ique i n c l u d e (a) improvement of d e t e c t i o n l i m i t s (up t o t w e n t y f o l d ) i n u ran ium m a t r i c e s by a c c u r a t e b a c k g r o u n d s u b t r a c t i o n ; (b) d e t e r m i n a t i o n o f ma jo r , minor and t r a c e e l e m e n t s i n s t a n d a r d r e f e r e n c e m a t e r i a l s wi th 0.1-0.2? RSN; and (c) c o r r e c t i o n of human e r r o r s in sample p r e p a r a t i o n . REFERENCES: [ 1 ] Lorber , A. and Goldbar t , Z . , Anal. Chem., j j6 , 37 (1984) . [2 ] Lorber , A., Go ldbar t , Z . and Eldan, M., Anal. Chem., j>5, 43 (1984) .

ANALYSIS OF SOLID SAMPLES IN ICP-ES BY DIRECT INSERTION OF A CARBON CUP INTO THE TAIL OF THE SOURCE A. Lorber and Z. Goldbar t

S o l i d s a m p l e s c a n b e i n t r o d u c e d i n t o t h e ICP u s i n g two t e c h n i q u e s : (a) t r a n s f e r t o t h e g a s s t r e a m e i t h e r by e v a p o r a t i o n or f l u i d i z a t i o n , (b) d i r e c t s o l i d s a m p l e i n t r o d u c t i o n i n t o t h e p l a s m a on a g r a p h i t e rod o r i n a g r a p h i t e cup , t h e r e b y c o m b i n i n g t h e e v a p o r a t i o n and e x c i t a t i o n s t a g e s . In the p r e s e n t i n v e s t i g a t i o n a g r a p h i t e cup was i n s e r t e d l a t e r a l l y i n t o the lower p a r t of the a n a l y t i c a l o b s e r v a t i o n zone, s e v e r a l m i l l i m e t e r s above the work c o i l . The d e v i c e was e v a l u a t e d for the m u l t i -t r a c e e l e m e n t a n a l y s i s o f u r a n i u m m a t r i c e s . The p r o p o s e d t e c h n i q u e overcomes the d i f f i c u l t i e s of s p e c t r a l l i n e i n t e r f e r e n c e s w i th r e s u l t a n t enhanced l i m i t s of d e t e c t i o n in the range 0.02-5 yg/g wi th RSD of l e s s than 10%. Sample th roughout is r e l a t i v e l y h igh and the same e x c i t a t i o n u n i t may be used for t he a n a l y s i s of l i q u i d and s o l i d samples .

APPLICATION OF THE GENERALIZED INTERNAL REFERENCE METHOD TO HIGH ACCURACY ASSAY OF METALLURGICAL SAMPLES BY INDUCTIVELY COUPLED PLASMA [ 1 ] A. Lorbe r , Z. Goldbar t , A. Hare l , E. S h a v i t and M. Eldan

Determinat ion of major c o n s t i t u e n t s r e q u i r e s accuracy of b e t t e r than \%, which i s n o t a c h i e v a b l e by i n d u c t i v e l y c o u p l e d p l a s m a ( ICP) . Use of t h e g e n e r a l i z e d i n t e r n a l r e f e r e n c e method (GIRM) t o a c h i e v e t h i s goa l was examined . The a d e q u a c y of t h e GIRM was t e s t e d for low a l l o y s t e e l s and a luminum a l l o y s . Major , minor and t r a c e e l e m e n t s were d e t e r m i n e d s i m u l t a n e o u s l y on a d i r e c t r ead ing spec t romete r . P r e c i s i o n of b e t t e r than 0.2? was a c h i e v e d . S p e c t r a of t h e major e l e m e n t and a r g o n were used a s i n t e r n a l r e f e r e n c e and no i n t e r n a l r e f e r e n c e e l e m e n t was added . S i n g l e p o i n t c a l i b r a t i o n was used to determine c o n c e n t r a t i o n s v a r y i n g up to two o r d e r s of magnitude. REFERENCE:

[ 1 ] L o r b e r , A., G o l d b a r t , Z. , H a r e l , A., S h a v i t , E. and E l d a n , M., Spec t rochim. Acta 4_VB, 105 (1986) .

COMPENSATION FOR BACKGROUND VARIATION BY GENERALIZED BACKGROUND SUBTRACTION A. Lorbe r , Z. Goldbart and A. Hare l

A c c u r a t e s u b t r a c t i o n of t h e b a c k g r o u n d s i g n a l a t t h e a n a l y t i c a l w a v e l e n g t h i s a c r i t i c a l s t e p in the d e t e r m i n a t i o n of the t r u e a n a l y t i c a l

193

s igna l . A mathematical treatment of mul t ip le point data tha t removes the background contr ibut ion to the data was developed. Each data point d i i s corrected by subtract ing the term bjE b^d^/ib^ where b< i s the background v a l u e and the summation i s taken over a l l p o i n t s . This background s u b t r a c t i o n method was a p p l i e d to the d e t e r m i n a t i o n of low amounts of uranium in phosphoric acid by induct ive ly coupled plasma ~ atomic emission spectrometry in the presence of spec t r a l in terferences . Several spec t r a l p o i n t s in the c l o s e v i c i n i t y of U I I 385.^66 nm were used to r e s o l v e the o v e r l a p p e d s p e c t r a . Complete s p e c t r a l r e s o l u t i o n and a f o u r - f o l d improvement of the detection l imi t were achieved by implementing the method introduced here.

NOVEL APPLICATIONS OF MTF MEASUREMENTS USING MOIRE DEFLECTOMETRY [ l ] 0. Kafri, I . Gla t t , E. Keren and A. Livnat

The e f f e c t of ob j ec t d i f f u s i v i t y on the MTF (modula t ion t r a n s f e r func t ion) measured in a moire d e f l e c t o m e t e r was demonstrated. The d i f f u s i v e MTF can be i s o l a t e d and measured independently of d i f f ract ion effects . A propagator which expresses the change in MTF with the path was def ined and demonstra ted on a c o l l o i d a l s o l u t i o n s e r v i n g as the t e s t e d object. Good agreement was found between the formalism and experimental r e s u l t s . REFERENCE: [1] Kafr i , 0., G l a t t , I . , Keren, E. and L ivna t , A., in Proceedings of the

Second I n t e r n a t i o n a l Techn i ca l Symposium on Appl ied Science and Engineering, Cannes, France, 1985 (SPIE), in press .

PHASE OBJECT MICROSCOPY USING MOIRE DEFLECTOMETRY+ [1] J . Krasinski*, D. F. Heller* and 0. Kafri

A new and s imple method for microscopic a n a l y s i s of phase o b j e c t s was proposed and demonstrated. The method, based on moire ray def lec t ion ana lys i s (deflectometry), combines the s impl ic i ty and low cost of sch l i e ren microscopy with c e r t a i n q u a n t i t a t i v e aspects of interference microscopy. This new method has severa l advantages in f l e x i b i l i t y and ease of use and in t e rp re t a t ion . REFERENCE: [1] Krasinski, J., Heller, D. F. and Kafri, 0., Appl. Opt. 24, 3032 (1985).

DIRECT BIREFRINGENCE MEASUREMENTS USING KOIRE RAY DEFLECTION TECHNIQUES'*" [1]

D. F. Heller*, 0. Kafri and J. Krasinski*

Moire ray deflection analysis techniques can provide fast, simple,

and sensitive quantitative methods for direct measurement of optical

This work was performed at Allied Corporation, Mount Bethel, NJ, U.S.A.

Allied Corporation, Mount Bethel, NJ, U.S.A.

194

b i r e f r i n g e n c e . Two of t h e s e t e c h n i q u e s were d e s c r i b e d , a n a l y z e d , and demons t ra ted . REFERENCE: [1] H e l l e r , D. F . , K a f r i , 0 . and K r a s i n s k i , J . , Appl. Opt. 24, 3037 (1985)

REAL-TIME MOIRE VIBRATION ANALYSIS OF DIFFUSIVE OBJECTS* [12

0. K a f r i , Y. B. Band*, T. Ch in** , D. F. H e l l e r * * and J. C. W a l l i n g An o p t i c a l moire t echnique for r e a l - t i m e m e t r o l o g i c a l measurements

was p r o p o s e d . T e m p o r a l b e h a v i o r of p e r i o d i c a s w e l l a s n o n p e r i o d i c v i b r a t i o n s can be a c c u r a t e l y d e t e r m i n e d . We d e m o n s t r a t e d t h e method by measuring the mechanical v i b r a t i o n of a d r iven speaker membrane. REFERENCE:

[ 1 ] K a f r i , 0. Band, Y. B., Chin, T., H e l l e r , D. F . and W a l l i n g , J . C ,

Appl. Opt. 24, 240 (1985) .

IMMUNITY TO SHOCK AND VIBRATION IN MOIRE DEFLECTOMETRY Cl] E. Keren

The supremacy of moire d e f l e c t o m e t r y over any form of i n t e r f e r o m e t r y r e g a r d i n g s u s c e p t i b i l i t y to shock and v i b r a t i o n was demonstrated. S e v e r a l expe r imen ta l c o n f i g u r a t i o n s of the s e tup a p p r o p r i a t e fo r envi ronments wi th va ry ing degrees of n o i s e were developed. REFERENCE: [1] Keren, E . , Appl. Opt. 2_4, 3028 (1985) .

MOIRE DEFLECTOMETRY - A RAY DEFLECTION APPROACH TO OPTICAL TESTING [1] 0 . Kafr i and I . G l a t t

A n o v e l t e c h n i q u e , moire d e f l e c t o m e t r y , for ray d e f l e c t i o n mapping was developed. Numerous expe r imen ta l t echn iques f o r d i a g n o s t i c s of phase o b j e c t s and s p e c u l a r s u r f a c e s , for s h e a r i n g a n a l y s i s , microscopy, and MTF d e t e r m i n a t i o n , b a s e d on mo i r e d e f l e c t o m e t r y were c o n s i d e r e d . The wide range of a p p l i c a t i o n s encompasses l a s e r beam d i a g n o s t i c s , c h a r a c t e r i z a t i o n of o p t i c a l componen t s , f l o w v i s u a l i z a t i o n i n wind t u n n e l s , t e m p e r a t u r e mapping of f lames , t u r b u l e n c e s tudy, and r e a l time t r a c k i n g of t r a n s i e n t phenomena l i k e thermal l e n s i n g . REFERENCE: [1 ] Kaf r i , 0. and G l a t t , I . , Opt. Eng. 24 , 944 (1985).

MOIRE DEFLECTROMETRY WITH PURE SINUSOIDAL GRATINGS [1] E. Keren, A. Livnat and I . G l a t t

The e f f e c t of us ing a s i n u s o i d a l g r a t i n g i n s t e a d of a Ronchi r u l i n g as the o b j e c t g r a t i n g in moire d e f l e c t o m e t r y was demonstrated. The method

This work was performed a t A l l i e d Corpora t ion , Mount B e t h e l , NJ, U.S.A. Ben-Gurion U n i v e r s i t y of the Negev, Beer-Sheva A l l i e d Corpora t ion , Mount B e t h e l , NJ, U.S.A.

195

r e d u c e s t h e d i f f r a c t i o n b l u r , wh ich h i n d e r s t h e u s e of t h e c o n v e n t i o n a l m o i r e d e f l e c t o m e t e r f o r o b j e c t s of l o c a l l y v a r y i n g f o c a l l e n g t h s . The t e c h n i q u e combines most of t h e a d v a n t a g e s of m o i r e d e f l e c t o m e t r y and shear ing i n t e r f e r o m e t r y . REFERENCE:

[1] Keren, E . , L i v n a t , A. and G l a t t , I . , Opt. L e t t . U>» 167 (1985) .

SLOPE AND DEFORMATION MAPPING BY GRATING PROJECTION TECHNIQUE [ l ] A. L ivna t and 0 . Kafr i

We demonst ra ted a s imple g r a t i n g p r o j e c t i o n t echn ique for s l o p e and deformation mapping of l a r g e d i f f u s i v e o b j e c t s . The method i s an e x t e n s i o n of t h e m u l t i s l i t l i c h t s c h n i t t v e r f a h r e n technique . REFERENCE: [1] L i v n a t , A. and Kaf r i , 0 . , Opt. Eng. 24 , 150 (1985) .

LINE THINNING ALGORITHM OF NEARLY STRAIGHT MOIRE FRINGES 0 . Kafr i and B. Ashkenazi

A s imple none i t e r a t i v e l i n e t h i n n i n g a l g o r i t h m which i s s u i t a b l e for n e a r l y s t r a i g h t i n t e r f e r o m e r t r i e and moire f r i n g e s was proposed. The a l g o r i t h m was found t o be f a s t and a c c u r a t e . An e r r o r a n a l y s i s was a l s o made.

DETERMINATION OF COLLOID CONCENTRATION FROM RADIATION TRANSVERSE MODES MULTIPLICATION 1 . G l a t t , H. Tob i a s , H. Cohen and 0 . Kaf r i

A n o v e l o p t i c a l method f o r d e t e r m i n i n g t h e c o n c e n t r a t i o n of c o l l o i d s , c o n s i s t i n g of p a r t i c l e s l a r g e r than the wave leng th of l i g h t , was p r o p o s e d . The method e m p l o y s m o i r e d e f l e c t o m e t r y f o r m e a s u r i n g t h e i n c r e a s e of t h e d i v e r g e n c e of a l i g h t beam, p a s s i n g t h r o u g h a c o l l o i d a l s o l u t i o n , which r e s u l t s from the augmentat ion of the number of t r a n s v e r s e modes of r a d i a t i o n .

DERIVATION OF THE GOVERNING EQUATIONS FOR MOIRE INTERFEROMETRY PATTERNS* [ 1 ]

A. Livnat and D. Pos t* The e q u a t i o n s d e s c r i b i n g t h e g r a d i e n t and i n c l i n a t i o n of f r i n g e s in

moire i n t e r f e r o m e t r y were d e r i v e d from the b a s i c laws of d i f f r a c t i o n and i n t e r f e r e n c e . A v e c t o r i a l r e p r e s e n t a t i o n of t h r e e - d i m e n s i o n a l d i f f r a c t i o n employs inc idence and emergence v e c t o r s in t h e p l a n e of the g r a t i n g ; the r e p r e s e n t a t i o n i s e s p e c i a l l y w e l l s u i t e d for t h i s type of a n a l y s i s . The

T h i s work was p e r f o r m e d a t V i r g i n i a P o l y t e c h n i c I n s t i t u t e and S t a t e U n i v e r s i t y , Blaoksburg , VA, U.S.A. V i r g i n i a P o l y t e c h n i c I n s t i t u t e and S t a t e U n i v e r s i t y , B l a c k s b u r g , VA, U.S.A.

196

analysis proves that the patterns of moire interferometry and geometrical

moire are governed by identical relationships.

REFERENCE:

[ 1 ] L ivna t , A. and P o s t , D. , Exp. Mech. 2 5 , 360 (1985) .

USE OF A Hglg SOLID STATE DETECTOR IN GAMMARAY DENSIMETRY M. P a s i , 0 . Shahal and A. Matmor

Most of the y -dens ime te r s now in use have an i o n i z i n g chamber a s a d e t e c t o r . The r a t e measurement i s q u i t e s t a b l e , but the f a c t t h a t a l l the p h o t o n s a r e c o u n t e d , w i t h o u t e n e r g y s e l e c t i o n , l e a d s t o s e r i o u s p e r t u r b a t i o n s due t o t h e b u i l d - u p e f f e c t (a s e c o n d a r y r a d i a t i o n - m a t t e r i n t e r a c t i o n e f f e c t , g e n e r a t i n g low-energy photons, which competes wi th t he n o r m a l Beei—Lambert a b s o r p t i o n e f f e c t ) . The a l t e r n a t i v e use of a s c i n t i l l a t o r - d e t e c t o r ( p e r m i t t i n g t h e s e l e c t i o n of t h e d e s i r e d medium^ e n e r g y p h o t o n s ) s o l v e s t h e p r o b l e m , b u t h a s a n o t h e r d i s a d v a n t a g e , t h e i n s t a b i l i t y of t h e c o u n t i n g r a t e , due t o dependence on t h e h i g h - v o l t a g e a p p l i e d and the ambient t empera ture ( the b u i l t - i n p h o t o m u l t i p l i e r be ing the main source of i n s t a b i l i t y ) .

We h a v e b u i l t a new t y p e of y - d e n s i m e t e r , w o r k i n g w i t h a m e r c u r i c i o d i d e s o l i d s t a t e d e t e c t o r ( b u i l t by t h e Yissum Co. J e r u s a l e m ) . The count ing r a t e i s independent of the a p p l i e d high v o l t a g e and the ambient t empera tu re , w i th in the ranges 200 to 1100 V and 20 to 60°C.

The p o s s i b i l i t y of c o l l e c t i n g , d u r i n g weeks , r a t e f i g u r e s w i t h i n t e r n a l d e v i a t i o n s no g r e a t e r than ±2, p e r m i t t e d i n t r o d u c i n g improvements in the c a l i b r a t i o n of the ins t rument . The o f ten-used l i n e a r i z a t i o n of the d e n s i t y / c o u n t i n g - r a t e r e sponse cu rve i s of course i n c o r r e c t , the dependence b e i n g e x p o n e n t i a l . However , a l s o t h e improved method of b u i l d i n g an e x p o n e n t i a l curve between the two c a l i b r a t e d l i m i t s of the d e n s i t y - r a n g e i s i n a c c u r a t e , b e c a u s e t h e p - f a c t o r of t h e a b s o r p t i o n - e q u a t i o n ( = t h e m a s s -a b s o r p t i o n - c o e f f i c i e n t , MAC), which depends on the atomic composit ion of t h e medium, c h a n g e s c o n t i n u o u s l y w i t h i n t h e measu red d e n s i t y r a n g e . T h e r e f o r e , t h e b u i l d i n g of an a c c u r a t e r e s p o n s e - c u r v e r e q u i r e s t h e s p l i t t i n g of the range i n t o s e v e r a l s u b - s e c t i o n s ; the c o r r e l a t i v e v a l u e s of the d e n s i t y / c o u n t i n g - r a t e p a i r of each l i m i t between two s u b - s e c t i o n s a r e e x p e r i m e n t a l l y measu red , t h e mean MAC v a l u e w i t h i n each s u b - s e c t i o n i s c a l c u l a t e d and in t h i s way a new p o l y e x p o n e n t i a l cha in-shaped c a l i b r a t i o n c u r v e i s b u i l t ; such a cu rve a f fo rds inc reased p h y s i c a l accuracy.

We h a v e added a m i c r o p r o c e s s o r w i t h a s p e c i a l p rogram t o t h e i n s t r u m e n t . When p u t i n c a l i b r a t i o n mode, t h e i n s t r u m e n t a u t o m a t i c a l l y r e c o r d s t h e s e v e r a l c o r r e l a t i v e f i g u r e p a i r s , c a l c u l a t e s a l l t h e MAC v a l u e s , b u i l d s t h e p o l y - e x p o n e n t i a l c h a i n c u r v e and s t o r e s i t i n t h e memory. When put in m e a s u r i n g mode, t h e i n s t r u m e n t r e a d s t h e c o u n t i n g r a t e s , t r a n s f o r m s them t o d e n s i t y v a l u e s t h r o u g h t h e i n t e r n a l l y s t o r e d c a l i b r a t i o n t a b l e and d i r e c t l y d i s p l a y s t he d i g i t a l d e n s i t y f i gu re .

We have b u i l t a p r o t o t y p e of the ins t rument , which has s u c c e s s f u l l y passed f i e l d t e s t s . A commercial v e r s i o n w i l l be b u i l t soon.

197

CALIBRATION OF THE PROBE OF A HOT FILM ANEMOMETER FOR A LOW^-VELOCITY AND

VARIABLES-TEMPERATURE FLOW SYSTEM [1]

Y. Barnea and G. Oudiz

A measuring device based on a hot film anemometer was chosen for the

measurement of local low velocities in a variable-temperature medium. A

calibration facility was built for this probe. The measurement is made in

a tube with a fully developed velocity profile.

REFERENCE:

[1] Barnea , Y. and Oudiz, G., NRCN-538, 1985, in Hebrew.

A CONTACT.-rFREE NUCLEAR CONTINUOUS VOLUME-GAUGE, BASED ON NEUTRON SCATTERING M. P a s i , S . P i e s t u n and I . Caras

The cont inuous n u c l e a r volume^gauges, which a re base'? on the p r inc ip l e of cumulative gamma-radiation aDsorption by the measured medium suffer from quite low accuracy, owing to the exponential dependence of tha t absorption on the width of the i r rad ia ted medium-layer. This complicates the approximated l i n e a r i z a t i o n , e s p e c i a l l y towards the ends of the measuring range. In large ve s se l s , with heights of 10 meters and more, the accuracy of such a gauge may drop to + 5%, thus l e a v i n g an u n c e r t a i n t y range which can sometimes reach 1 meter.

In 1979, we r e p o r t e d on a p o r t a b l e l e v e l - g a u g e , based on neu t ron s ca t t e r i ng [ 1 ] . The heart of that gauge i s a chemical fast-neutron source (Am-Be type) l i nked to a t h e r m a l - n e u t r o n d e t e c t o r (BF , - type ) . If such a device i s moved along the outer wal l of a vessel containing some hydrogen bearing l iquid , a la rge difference in the counting-rate of the detector i s recorded between the l i q u i d and the l i q u i d - f r e e a r e a s , owing to the thermal-neutron generation and sca t t e r ing of the l iquid layer . We have now developed that por table gauge into a b u i l t - i n accurate i n d u s t r i a l volume-meter. In t h i s instrument, the neutron-source and the BF, detector move, l i n k e d t o g e t h e r , in a high l i f t running a long the e n t i r e w a l l of the v e s s e l , w e l l enc losed in a duct ; the d r iv ing -moto r of the l i f t i s run by the thermal _neutror i<-ra te coun te r , which p o s i t i o n s the s o u r c e - d e t e c t o r d e v i c e upwards or downwards, accord ing to i t s p o s i t i o n r e l a t i v e to the l iqu id l e v e l .

A prototype was b u i l t , which has been working continuously for a few months. The neutron source may be l inea r or annular, with a s trength of 50 to 200 mCi. The BF, detector i s 8 Inches in length and 1 inch in diameter. The device i s shielded by a spec i a l l y designed cadmium-paraffin p l a t e . The moving device comprehends the source-detector, the pre-amplif ier and the h igh-vol tage supply; the moving cable conveys the 9 v o l t supply to the device and re turns i t s amplified pulses to the counter, which dampers them through an 8 second time constant, in order to smooth the command reac t ions sen t to the motor. Under normal i n d u s t r i a l l i q u i d motion (speeds up to 3 cm/min), the device follows the l iqu id l e v e l with f i d e l i t y , be t t e r than t 1.5 cm, even i f the s t e e l w a l l of the v e s s e l i s 15 mm in t h i c k n e s s . An

198

e l e c t r o n i c s i t u a t i o n - b r o a d c a s t e r sends the p o s i t i o n of the d e v i c e t o the c o n t r o l room, where i t i s d i g i t a l l y d i s p l a y e d . REFERENCE:

[ 1 ] P a s i , M. and Ass ido , C. , i n : IA-1356, 1980, p . 235.

NOVEL DOUBLE REFLECTION POLARIZATION PRISM [ 1 ]

U. Laor , H. Lotem and M. Blumenfeld A n o v e l p o l a r i z a t i o n prism was made from a u n i a x i a l c r y s t a l . L igh t

p o l a r i z a t i o n i s ob ta ined by the double r e f l e c t i o n e f f e c t , an e f f e c t which i s e q u i v a l e n t t o t h e known e f f e c t of d o u b l e r e f r a c t i o n . I n d o u b l e r e f l e c t i o n t he v a l u e s of the r e f r a c t i v e index a s s o c i a t e d wi th a l i g h t wave a r e , In g e n e r a l , changed upon r e f l e c t i o n i n s i d e t he a n i s o t r o p i c m a t e r i a l . I n t h e g e n e r a l c a s e , where t h e i n c i d e n t wave i s u n p o l a r i z e d , upon r e f l e c t i o n t h e wave Is s p l i t I n t o two o r f o u r r e f l e c t e d w a v e s , e a c h r e s u l t i n g from a d i f f e r e n t chanre in the v a l u e of the r e f r a c t i v e ind°x.

I n t h i s work, we d e a l t wi t i i o i . n p l s c o n f i g u r a t i o n s of r e c t a n g u l a r double r e f l e c t i o n p o l a r i z a t i o n pr isms made of s apph i r e . In t he s i m p l e s t p r i s m , t h e o p t i c a x i s of t h e c r y s t a l was o r i e n t e d p a r a l l e l t o t h e p r i s m base and t o t h e p r i s m e n t r a n c e f a c e . I t i s e a s y t o show t h a t an i n c i d e n t p l a n e wave s p l i t s i n t h e p r i s m i n t o two p o l a r i z e d waves s e p a r a t e d by 69 = ( n e - n 0 ) / n e . Upon e x i t i n g t h e o u t p u t f a c e of t h e p r i s m , a d d i t i o n a l d i v e r g e n c e occurs due to the r e f r a c t i o n a t t he c r y s t a l / a i r i n t e r f a c e . The n e t s e p a r a t i o n angle i s fie = n e ~ n o ~ ^ m r a d -REFERENCE:

[1 ] Laor , U., Lotem, H. and B l u m e n f e l d , M., i n : M e e t i n g of O p t i c a l E n g i n e e r i n g in I s r a e l , 4 t h , T e l - A v i v , May 1985 , A s s o c i a t i o n of Engineers in I s r a e l , p . 26 .

AN AUTOMATIC SYSTEM FOR MEASURING THE LEVEL OF LOW DENSITY GUN POWDER IN FULLY ASSEMBLED BULLETS

Y. E i s e n , D. Kedem, E. Izak and E. Y e l l i n A c c u r a t e measuremen t of t h e l e v e l o f t h e gun powder i n 0 . 4 5 " and

0 .38" b u l l e t s , used fo r h a n d g u n s , i s e x t r e m e l y i m p o r t a n t . The n o m i n a l h e i g h t of t h e gun powder i n t h e s e b u l l e t s i s a b o u t 5 mm. An e x c e s s of s m a l l q u a n t i t i e s of gun powder cor responding t o 1.5 mm in h e i g h t may cause t he e x p l o s i o n of the gun b a r r e l . There fo re , s t r i n g e n t q u a l i t y c o n t r o l of the p roduc t s i s n e c e s s a r y .

An au tomat i c system for a c c u r a t e l y measur ing the gun powder l e v e l was b u i l t and a s s e m b l e d on t h e c o n v e y o r of a p r o d u c t i o n l i n e . The produc t ion r a t e of the l i n e was about 100 b u l l e t s per minute. The system i n s t a l l e d measured the l e v e l of the gun powder wi th an accuracy of ±1 mm w i t h a s t a t i s t i c a l a c c u r a c y of a c c e p t i n g d e f e c t i v e b u l l e t s or r e j e c t i n g good b u l l e t s of 1 i n 10^ and 1 i n 1 0 ^ , r e s p e c t i v e l y . These r e s u l t s were ob ta ined with a gun powder of d e n s i t y 0.65 g/cnH. Much b e t t e r performance was ach ieved wi th a common gun powder of d e n s i t y 0.95 g/crrP.

199

The system is comprised of a) a radia t ion source b) high e f f i c i e n c y s o l i d s t a t e d e t e c t o r s c) an amplification system d) a PC-type microcomputer.

The computer analyzes the data using e i ther predetermined or dynamic ca l i b r a t i on factors and a simple algorithm for re jec t ion or acceptance.

A WATER COOLED ELECTRON GUN FOCUSED AT 90°, 270° R. Avida and M. Friedman

A p r e v i o u s study [ 1 ] , demonstra ted the f e a s i b i l i t y of a long and symmetric e l e c t r o n gun focused a t 90° , 270°. In p r a c t i c e , only d i r e c t cooling of the gun anode su f f i c i en t ly guarantees low pressure at the high vacuum end of the d i f f e r e n t i a l l y pumped system. We therefore required a r e l a t i v e l y th i ck anode (21) ram), thp. i n t e r i o r of which accommodated the c i r cu l a t i ng cooling water. This c a l l e d for a readjustment of the optimal pa ramete rs , see Fig. 2. The performance of the r e s u l t i n g s e t of pa ramete rs , shown in Fig. 3, produced a narrow and long focus. I t a l s o turned out tha t the new to lerances were e a s i l y achieved.

T> 6 mm

32 mm

- 32 mm

J9,2mrn I 16mm !

16 mm

•filament 2.8mm

Fig. 2 A water-cooled e lec t ron gun

focused a t 90°, 270°

Fig. 3

Calculated electron trajectories

of the designed gun

REFERENCE:

[1] Avida, R., Friedman, M. and Erez, C , i n : IA-1112, 1985, p. 168.

200

A COMPENSATION DEVICE FOR THE NEGATIVE CHARGING OF THE MAIN CAPACITOR IN A

COPPER VAPOR LASER

G. Gal, S. Kamin and E. Miron

Typical copper-vapor laser performance is limited by impedance

mismatch between the laser plasma and the discharge circuit. Part of the

energy, transferred to the plasma, recharges the main capacitor negrtively,

so that the thyratron is subjected to a negative voltage during recovery

time. An excess of negative voltage disturbs the thyratron recovery. To

overcome this disturbance a compensation device for the negative charging

of the main capacitor was developed. The device permits a quick discharge

of the main capacitor to an acceptable level for thyratron recovery. This

development allowed the laser to operate with lower neon pressure, leading

to an increase of about 30? in output power.

HEATnTRANSFER LABORATORY - GOALS AND MEANS [1]

Y. Barnea, G. Oudiz and I. Shai

The infrastructure of a heat-transfer laboratory was laid down in

the framework of thermohydraulic studies around a research reactor. The

construction of the system permits flexibility in the treatment of subjects

, connected to normal and emergency operations. The system is first operated

in the one-phase (liquid) regime; future studies and operations will be

extended to the two-phase regime. Calculations on the experimental

characterization of the mixed convection regime (a combination of forced

and free convection) were made in the "infinite" lattice geometry. Similar

calculations will be performed for various experiments which require

substitution of the experimental region, using all the general auxiliary

systems.

REFERENCE:

[1] Barnea, Y., Oudiz, G. and Shai, I., NRCN(TN)-067, 1985, in Hebrew.

ERROR PROPAGATION AND FIGURES OF MERIT FOR QUANTIFICATION EY SOLVING MATRIX

EQUATIONS

A. Lorber

Quantification from one-dimensional data permits the simultaneous determination of a l l components contributing to a spectrum. However, the applicabil i ty of the procedure is limited because of the figures of merit; error propagation, s igna l - to -no i se , l imi t of detect ion, precision, accuracy, s e n s i t i v i t y and s e l e c t i v i t y are not determined for each component. I t was suggested that by considering the "net analyte signal", error propagation and other figures of merit are defined for each component. Net analyte signal is defined as the part of the signal which is orthogonal to the spectra of the other components. The mathematical resul ts were applied to absorbance data of r» four RNA nucleotide mixture, and i t was found that the prediction of both precision and accuracy are good.

201

ERROR PROPAGATION IN QUANTIFYING CHEMICAL COMPOSITION FROM TWO-DIMENSIONAL DATA ARRAYS BY THE RANK ANNIHILATION FACTOR ANALYSIS METHOD A. L o r b e r

T w o - d i m e n s i o n a l d a t a a r r a y s ( such a s those ob ta ined by the v i d e o f l u o r o m e t e r , LC/IR-UV-MS) are i n h e r e n t l y advantageous over one-d imens iona l da ta v e c t o r s (chromatograms, s p e c t r a ) for q u a n t i f i c a t i o n purposes. Quantification of an ind iv idua l component in a mixture which has a known re sponse , wi th no need to know the r e sponses of o the r components, i s p o s s i b l e from such a r r a y s . The mathemat ica l technique i s the rank a n n i h i l a t i o n f a c t o r a n a l y s i s (RAFA) method. The mechanism of e r r o r propagation, e r ror bounds for each component, and rank degeneracy indicator for the RAFA were considered. The r e s u l t s of a simulation study indicate that error propagation occurs only when there i s a rank degeneracy. The e r r o r bound s u c c e s s f u l l y p r e d i c t e d e r r o r a m p l i f i c a t i o n as w e l l as reduction. The advised rank degeneracy c r i t e r ion succeeded in determining rank degeneracy.

PROCESS PLANT FAULT DIAGNOSIS BY EXPERT SYSTEM TECHNIQUES M. Ben-Haim, D. Peled, and Z. Boger

On l i ne diagnostic t oo l s can he lp the operator of a process p l an t to i d e n t i f y and q u i c k l y c o r r e c t f a u l t s in the equipment or p r o c e s s , thus ma in ta in ing the sa fe and economical o p e r a t i o n of the p l a n t . Such a t o o l was developed, using expert system techniques, and implemented on an IBM PC microcomputer.

An advanced e lec t ron ic "spread-sheet" program was used, which proved to be very user - f r iendly at a l l phases: development of the software s h e l l , enter ing the expert diagnostic knowledge and t rouble-shoot ing r u l e s , and using the f a u l t diagnosis program by p lan t operators.

The program cons is t s of five d i s t i n c t modules: a) User interface - data input module using the spread-sheet i n t e r a c t i v e features and database f a c i l i t i e s for entering the observed f a u l t symptoms, as determined by the operator. To help the operator, process equipment and instrumentation block diagram is displayed. b) Knowledge base - da ta base which c o n s i s t s of the r u l e s g iven by the expert, for commonly observed symptoms of equipment or process malfunction, t o g e t h e r with numer ica l pe rcen tage e s t ima te of the conf idence in the r e l a t i o n between the symptom and the f a u l t . The r u l e s are g iven in the form of If-Then-Else sentences. c) Context - a module which cons is t s of a database, formed while keeping track of the solut ion process. d) In fe rence mechanism - which combines the con tex t module wi th the knowledge-base to diagnose f a u l t s by the observed symptoms. The diagnosed f a u l t s and sugges ted remedia l a c t i o n are p resen ted to the o p e r a t o r as a l i s t in descending probabi l i ty order. e) Explanation - th i s module l i s t s the symptoms which were used to reach each suggested cause. The explanation i s useful in increasing the operator

202

conf idence in the d i a g n o s i s and to e n a b l e t he expe r t t o monitor r u l e s and conf idence p e r c e n t a g e s .

The program was implemented for the f a u l t d i a g n o s i s of a l o w - l e v e l r a d i o a c t i v e w a s t e w a t e r e v a p o r a t o r i n s t e a d y s t a t e o p e r a t i o n w i t h 22 ins t rument reading.? and 12 v a l v e s and pumps s t a t e s . Four hundred r u l e s were i d e n t i f i e d , and once t h e symptoms were e n t e r e d , a l i s t of d i a g n o s e d f a u l t s was found i n 5 s e c o n d s . F u t u r e work i s p l a n n e d t o i m p l e m e n t a d i r e c t da ta l i n k for t r a n s f e r r i n g ins t rument r e a d i n g s and equipment s t a t e s to the micro-computer , w i thou t the need for o p e r a t o r i npu t .

RECOGNITION OF HANDPRINTED HEBREW CHARACTERS USING FEATURES SELECTED IN THE HOUGH TRANSFORM SPACE* [1 ] M. Kushnir , K. Abe and K. Matsumoto

A u t o m a t i c i d e n t i f i c a t i o n of h a n d p r i n t e d Hebrew c h a r a c t e r s was deve loped . The r e c o g n i t i o n model d e v i s e d c o n s t i t u t e s a m u l t i - s t a g e system. In the f i r s t s t a g e a coa r se c l a s s i f i e r a l l o c a t e s the inpu t p a t t e r n s i n t o one of 17 c a t e g o r i e s , b a s e d on t h e number and t h e l o c a t i o n of end p o i n t s w i t h i n p r e d e t e r m i n e d r e g i o n s i n t h e c h a r a c t e r s mat r ix . The second s t a g e uses f e a t u r e s e x t r a c t e d in the Hough t rans form space to c l a s s i f y c h a r a c t e r s a s s igned to each of 16 c a t e g o r i e s . The remaining one ca t ego ry , composed of s i m i l a r , s q u a r e - l i k e ( r o t a t e d L shape) c l a s s e s , i s r ecogn ized by s t r u c t u r a l a n a l y s i s and a s t a t i s t i c a l c l a s i f i e r . An a d d i t i o n a l s t e p of p o s t p r o c e s s i n g i s added t o c o m p e n s a t e f o r t h e s e n s i t i v i t y of t h e Hough t r a n s f o r m t o t h e e x i s t e n c e of s i m i l a r c l a s s e s w i t h i n some of the c a t e g o r i e s . Experiments were c o n d u c t e d w i t h a m u l t i - a u t h o r (^0 w r i t e r s ) d a t a b a s e . An a v e r a g e r e c o g n i t i o n r a t e of 8 6 . 9 ? was o b s e r v e d f o r t h e s y s t e m . T h i s compared f a v o r a b l y wi th the r e s u l t s of two o t h e r r e c o g n i t i o n methods. REFERENCE:

[1] K u s h n i r , M., Abe, K. and Matsumoto , K., P a t t e r n R e c o g n i t i o n 18 ,103 (1985) .

AVERAGER WITH ADAPTIVE THRESHOLDS

Y, Kaufman In some a p p l i c a t i o n s t h e measured i n p u t p a r a m e t e r i s r a n d o m l y

d i s t r i b u t e d . In t h e s e c a s e s i t i s v e r y i m p o r t a n t t o e s t i m a t e t h e mean v a l u e and the s t andard d e v i a t i o n . Sometimes t h e s e v a l u e s change ove r a few decades and for t h i s purpose the Averager wi th Adapt ive T h r e s h o l d s (AAT) was designed. In order to a v o i d ave rage r ou tpu t b l o c k i n g , t o o b t a i n f a s t t ime response and s m a l l ou tpu t f l u c t u a t i o n s , the AAT i n c l u d e s two a v e r a g e r s connected in s e r i e s . Because the t h r e s h o l d s adapt t h e m s e l v e s t o the inpu t s t a t i s t i c s , the a v e r a g e r t ime response i s s i g n i f i c a n t l y improved. The AAT

This work was performed a t Shizuoka U n i v e r s i t y , Hamamatsu, Japan Shizuoka U n i v e r s i t y , Hamamatsu, Japan

203

a l g o r i t h m i s based on s t a t i s t i c a l r u l e s and i t s r e s u l t s a re in good agreement with theory . F i n a l l y the e s t i m a t i o n a l g o r i t h m i s s imple and needs l i t t l e memory space, therefore i t can be implemented e f f ec t i ve ly in microcomputers.

AN INTERACTIVE COMPUTERIZED MECHANICAL TESTING SYSTEM ( I I ) G. Adam and R. Frenkel

The m&chanical m e t a l l u r g y l a b i s equipped with Instron un ive r sa l t e s t i n g machines and with an ins t rumented impact t e s t i n g dev ice (T in ius Olsen model 6H, p lus Dynatup 371). The f i r s t s tage of "computerizing" the laboratory was previously described [1 ] . The major changes in the system since then a re : a) The processor in the computer was changed and the computer's memory was

en l a rged so t h a t in e f f e c t the computer i s now a PDP11/23 with a core memory of 128k.

b) A hard disk (RL02) wi th a s t o r a g e c a p a c i t y of 10 megabytes was i n s t a l l ed .

c) A p lo t te r (HP model 7475A) was added. d) An RSX11 M PLUS o p e r a t i n g system was i n s t a l l e d as the main o p e r a t i n g

system of the computer, thus p e r m i t t i n g the system t o work in a r e a l multi-user mode.

e) A l l the r e l e v a n t programs which were e a r l i e r deve loped for the RT11 environment, were changed to run on the new system.

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204

I n t h i s new c o n f i g u r a t i o n , up t o 1 2 t e r m i n a l s can be c o n n e c t e d t o t h e c o m p u t e r , and a l l can work t o g e t h e r in a t ime s h a r i n g mode. Two (or more) INSTRON m a c h i n e s can be o p e r a t e d c o n c u r r e n t l y , w h i l e a t a t h i r d t e r m i n a l the r e s u l t s of a p r e v i o u s experiment can be ana lyzed . During the a n a l y s i s , u s i n g t h e YOUNG program [ 1 ] one can p r o d u c e a h a r d copy of t h e s t r e s s / s t r a i n c u r v e i n d i c a t i n g t h e c a l c u l a t e d Young Modulus and p r o p o r t i o n a l l i m i t . F i g u r e 4 shows a t y p i c a l summarizing s t r e s s - s t r a i n cu rve of a s t a t i c s t r a i n ag ing e f f e c t i n a s u b s t i t u t i o n a l a l l o y .

A f a s t (1 MHz) da ta logger i s now be ing deve loped which w i l l be a b l e t o s t o r e d a t a from t h e i m p a c t t e s t i n g m a c h i n e , and t r a n s m i t i t a t a r a t e a c c e p t a b l e to the computer for a n a l y s i s and s t o r a g e . REFERENCE:

[ 1 ] F r e n k e l , R. and Adam, G.f An I n t e r a c t i v e C o m p u t e r i z e d M e c h a n i c a l T e s t i n g Sys t em, i n : IA-1101, 1983, p. 227.

A SOFTWARE PACKAGE FOR COMPUTERIZED INSTRUMENTED IMPACT TESTING G. Adam, Y. Rosenthal and M. Mark~Markowitch

A sof tware package was deve loped for da ta a c q u i s i t i o n and a n a l y s i s of impac t t e s t i n g . The p a c k a g e c o n s i s t s of 3 p r o g r a m s . The package was w r i t t e n in FORTRAN and i s being used on a PDP11/23 computer.

The f i r s t p rogram, IMPACTl, a c c e p t s e x p e r i m e n t a l d a t a f r o m a 5 D l O waveform d i g i t i z e r , and s t o r e s i t a s a a d a t a f i l e i n t h e compu te r . The o t h e r two p r o g r a m s , IMPACT2 and IMPACT3, a c c e p t a s i n p u t t h e d a t a f i l e s c r e a t e d by IMPACT1, perform v a r i o u s da ta a n a l y s e s and r e d u c t i o n o p e r a t i o n s on t h e e x p e r i m e n t a l d a t a , and p r o d u c e a s an o u t p u t , p r i n t e d o r p l o t t e d r e s u l t s ,

ACCURATE DETERMINATION OF THE VOLUME OF HORIZONTAL CYLINDRICAL TANKS WITH DISHED ENDS

Y. Kaufman Determinat ion of the volume of a h o r i z o n t a l tank approx imate ly has

been r e p o r t e d [ 1 - 3 ] . However, us ing a computer program for s i m u l a t i o n of a p r o c e s s , one can, a t the same time, a c c u r a t e l y determine t he volume of the tank, i n c l u d i n g i t s d ished ends. In t h i s wc-k the unknown volume and o t h e r pa ramete rs were a c c u r a t e l y found by us ing a HP-H1 C programmable c a l c u l a t o r . The computed r e s u l t s a r e in good agreement wi th theory . REFERENCES:

[1 ] Kowal.G. , Chem. Eng. SO (13) 130, 132 (1973) ; M < 1 6 ) 5 (1977) . [2 ] Ga l l agher , T . , Chem. Eng. 90 (17) 100 (1983) . [3 ] Chen, J . J . J . , Chem. Eng. 92 (11) 154 (1985) .

SOFTWARE SAFETY USING THE FTA TECHNIQUE

R. Greenberg F a u l t t r e e a n a l y s i s (FTA) i s a w e l l known and e f f e c t i v e method for

a n a l y z i n g hardware systems. A p o s s i b l e use of FTA in a sof tware embedded s y s t e m for t e m p e r a t u r e c o n t r o l was d e v e l o p e d . The a n a l y s i s was f i r s t

205

a p p l i e d t o b o t h t h e h a r d w a r e and s o f t w a r e s y s t e m s , b u t s u b s e q u e n t l y c o n c e n t r a t e s on t h e sof tware s e c t i o n . Two c r i t i c a l e v e n t s were d e t e c t e d by FTA and s t e p s were taken to overcome them. Although t h i s work r e l a t e s t o a s p e c i f i c s i t u a t i o n i t can be a p p l i e d to many c o n t r o l sys tems.

PAL ENABLES STATE CHANGE DETECTION D. Barak and A. Gabovitz

I t i s o f t e n n e c e s s a r y fo r a m i c r o p r o c e s s o r < - b a s e d s y s t e m t o d e t e c t s t a t e c h a n g e s i n one of s e v e r a l d i g i t a l i n p u t l i n e s , s u c h as s w i t c h e s , r e l a y s , e t c . U s u a l l y we connect each l i n e to an i n d i v i d u a l i n t e r r u p t p in , o r , a l t e r n a t e l y , c o n n e c t a l l t h e l i n e s t h r o u g h an Or g a t e t o a s i n g l e i n t e r r u p t . The f i r s t a l t e r n a t i v e i s q u i t e compl i ca t ed and e x p e n s i v e and t h e s econd d o e s n o t p e r m i t d e t e c t i o n of t r a n s i t i o n s from " 1 " t o " 0 " and v i c e v e r s a .

The b a s i c c i r c u i t d e s c r i b e d i n F i g . 5 d e t e c t s e v e r y t r a n s i t i o n of t h e INPUT l i n e . I n i t i a l l y both t he FF and the INPUT l i n e a r e in s t a t e "0". When t h e INPUT g o e s from "0" t o " 1 " t h e Xor g a t e t r a n s f e r s t h e " 1 " t o i t s o u t p u t , and t h e m i c r o p r o c e s s o r r e c e i v e s an i n t e r r u p t . The Acknowledge s i g n a l s t r o b e s t h a FF and t r a n s f e r s t h e Xor t o " 0 " , t h u s r e s e t t i n g t h e i n t e r r u p t . When t h e INPUT l i n e g o e s from " 1 " t o "0" , t h e p r o c e s s r e p e a t s i t s e l f and we g e t an i n t e r r u p t a g a i n . Thus t h e FF r e t a i n s t h e l a s t s t a t e of the INPUT l i n e and the Xor d e t e c t s any t r a n s i t i o n i n i t .

The c i r c u i t in Fig. 6 p r o v i d e s a s o l u t i o n for 8 d i g i t a l i npu t l i n e s . An o c t a l l a t c h ( I n t e l 8282) was used a s FF and an MMI PAL1601 was c o n f i g u r e d a s 8 Xors w i t h OR. The i n t e r r u p t h a n d l e r r o u t i n e c h e c k s t h e 8255 p o r t t o s e e which l i n e c a u s e d t h e i n t e r r u p t and t h e n s e n d s an acknowledge p u l s e to s t r o b e the l a t c h and r e s e t the i n t e r r u p t .

Adding more i npu t s i s q u i t e s t r a i g h t f o r w a r d , us ing the complementary ou tpu t from the PALs and connec t ing them to a Nand g a t e .

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207

DOCUMENTATION

The following publications were issued during the period January to

December 1985.

REPORTS

IA-1396

KRUMBEIN, A.D., SALZMANN, D., SZICHMAN, H. and ELIEZER, S. Plasmor: A laser^plasma simulation code.

IA-1 401 ABRASHKIN, S. Design of Tc-99m generators I. Physicochemical aspects.

IA-1 406 FAERMANN, S. Design and development of wide energy neutron REM equivalent spectrometerj-idosimeters based on polycarbonates and CR-39. (Ph.D.)

IA-1110 LOEB, A. Analytical models for the evolution of strong shock waves generated by high irradiance lasers in solids and fast spark discharges in gases. (M.Sc. in Hebrew).

IA-1412 RESEARCH LABORATORIES ANNUAL REPORT - 1984.

IA-1413 MARGALIOT, M. Measurement of the thyroidal iodine content by X-rays fluorescence. (M.Sc. in Hebrew).

IA-1414 KATZ, M. Design of a system for measuring displacement with an accuracy better than 10 m. (B.Sc.Te. in Hebrew).

211

IA-1116

CASPO, N. Coarse mesh methods for shielding and deep penetration calculations. (M.Sc. in Hebrew).

IA-1120 GANTS, E. Evacuation of the population as a means of mitigating the radiological effects following an accidental atmospheric release of radioactivity from a nuclear power plant. (M.Sc. in Hebrew).

NRCN-508 KOL, R. Comparison of two different separation techniques on the human lymphocytes morphology and sensitivity to gamma radiation. (M.Sc. in Hebrew).

NRCN-519 SHAI, I . and GILAD, I . Thermal aspects of heat sources buried in the ground. (In Hebrew).

NRCN-522 TEITELBAUM, Z. Calculation of binding constants and concentration of binding sites in a reaction of a ligand with a heterogeneous system of binding sites.

NRCN-531 BARAK, D. Distributed hierarchical radiation monitoring system. (M.Sc. in Hebrew).

NRCN-538 BARNEA, Y. and OUDIZ, G. Calibration of the probe of a hot film anemometer for low-velocity and variable-temperature flow system. (In Hebrew).

NRCN-540 RAVEH, A., INSPEKTOR, A., CARMI, U., RABINOVITZ, E. and AVNI, R. Oxidation reaction of pyrolytic carbon coating.

NRCN-546 BARNEA, Y. and SHAI, I. Evaluation of heat transfer coefficient in assisting mixed convection on a vertical element with uniform heat flux. (In Hebrew).

212

NRCN-5H7

MUNITZ, A., LIVNE, Z., COTLER, C. and DAGAN, U. Application of replication techniques to fractography of irradiated uranium fuel elements. (In Hebrew).

NRCN-5«9 MATHIAS, H. Austenite instability in austenitic steels due to hydrogenation. (Ph.D. in Hebrew).

NRCN-551

GILAD, I. Mechanical properties of austenitic S.S. in gaseous aggressive environment. (In Hebrew).

NRCN-552 BEN-SHACHAR, B., GERMAN, U. and WEISER, G. Measurement of some properties of LiF and CaF :Dy crystals irradiated by monoenergetic thermal neutrons. (In Hebrew).

NRCN-555 GREENSPAN, E. Fusion-fission hybrid reactors and nonproliferation.

NRCN-558 MUNITZ, A., LIVNE, Z., COTLER, C. and ADMON, U. A study on the damages caused to aluminum alloy type A5 following its irradiation by neutron fluences in a nuclear reactor. (In Hebrew).

NRCN-560 RAVEH, A., HERRMANN, B., MAROUANI, D. and RABINOVITZ, E. Joining of aluminium plates by epoxy resin. III. Effect of storage duration up to 52 months on the specimens.

NRCN-562 BEN-SHACHAR, B., YONA, S., LAICHTER, Y., GERMAN, U. and WEISER, G. The characteristics of CaF :Tm crystals {TLD-300) irradiated by electromagnetic radiation. (In Hebrew).

NRCN(ER)-023 DORON, E., OHAION, H. and ASCULAI, E. DOSE - A software package for the ca lcula t ion of integrated exposure r e su l t i ng from an accident in a nuclear power p lan t . (In Hebrew).

213

NRCN(TN)-040 LAVI, S.f AMIT, M., BIALOLANKER, G., KAMIN, S., KARMON*, S. and ERETZ--KEDOSHA*, R Measurement of the axis deviation of a phosphate baking revolving furnace using a laser beam. (In Hebrew).

NRCN(TN)-060 LAPID, J., GUISER, R., KEIDAR, Y., RAYMOND, A. and LEVY, E. Separation of neptunium from alloys and compounds. (In Hebrew).

NRCN(TN)-067

BARNEA, Y., OUDIZ, G. and SHAI, I. Heat-transfer laboratory - goals and means.

NRCN(TN)-073

RAVEH, A. and KIMMEL, G. The influence of heat treatments on some mechanical properties of A-286 steel. (In Hebrew).

211)

PAPERS PUBLISHED IN JOURNALS AND BOOKS*

ABRASHKIN, S. Epithermal neutron self-shielding in the reactor (n, T ) production

of 99Mo. Int. J. Appl. Radiat. Isot. 36 (5), 385-388, (May 1985).

ABU--SALBI*. N., KOURI*, D.J., BAER, M. and POLLAK*, E. A study of the quantal time delay matrix in collinear reactive scattering. J. Chem. Phys. 82 (10), 500-^508, (15 May 1985).

ABUSALBI*, N., KOURI*, D.J., SHIMA, Y. and BAER, M. Quantum mechanical study of the D+H — > HD+H reaction. J. Chem. Phys. 82 (7), 2650-2661, (15 Mar. 1985).

ACHIAM, Y. Critical dynamics of the kinetic Ising model on fractal geometries. Phys. Rev., B j$1_ (7), H732n3i», (1 Apr. 1985).

ACHIAM, Y. Critical relaxation of the one-dimensional Blume-Emery-Griffiths model. Phys. Rev., B 31 (1), 260r»265, (1 Jan. 1985).

ACHIAM, Y. Critical dynamics of the kinetic Ising model on the fractal Koch curves. Phys. Rev., B 32 (3), 1796*1801, (1 Aug. 1985).

ACHIAM, Y. Critical behavior of the kinetic ising model on Sierpinski carpets. Phys. Lett., A VV2 (3A), 161--»161», (21 Oct. 1985).

ALFASSI*, Z.B. and LAVI, N. Rapid determination of halogens in milk by instrumental neutron activation analysis. J. Radioanal. Nucl. Chem. 90 (2), 395-100, (July 1985).

AMIR, S. On the degree of interdisciplinarity of research programs: a quantitative assessment. Scientometrics §_ (1-2), 117-136, (1985).

AMIR, S.

Environmental research in Israel. (In Hebrew). In: Environmental quality in Israel. Vol. 11, 1985. p.309~-312.

*Authors from other Institutes are indicated by asterisks.

215

ANONYMOUS ISORAD. In: Electro optics & lasers - 1984; high technology & science based industries in Israel. (An Israel Economist publication). p.19-20. Also published in: Proposals for investments and industrial cooperation in Israel, August 1985. Tel"-Aviv, Dun & Bradstreet. p.32*33.

AVNI, R. and CARMI, U. Recent advances in ceramic coatings obtained by chemical vapour deposition and plasma processing deposition. Mater. Sci. Eng. 71 (1-2), 341~354, (May 1985). "International symposium on engineering ceramics, Jerusalem, Israel, 16^20 December 1984. Proceedings".

AVNI, R., CARMI, U., INSPEKTOR, A. and ROSENTHAL, I. The role of hydrogen in the radical polymerization mechanism of hydrocarbons and chlorosilanes in a low pressure microwave plasma. J. Vac. Sci. Technol. A 3. (4), 1813^1820, (Jul./Aug. 1985).

AZAR, Z., LOEBENSTEIN, H.M., APPELBAUM, G., AZOULAY, E., HALAVEE, U., TAMIR, M. and TUR*, M.

Aperture averaging of the two-wavelength intensity covariance function in atmospheric turbulence. Appl. Opt. 24 (15), 2401-2407, (1 Aug. 1985).

BAER, M. Quantum-mechanical study of the parallel molecule-surface reaction HC1 + S ->-> HS + CI. Chem. Phys. Lett. JH6. (5), 439-442, (17 May 1985).

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PASTER*, N., JUVEN*, B.J., GAGEL*, S., SAGUY*, I. and PADOVA, R. Preservation of a perishable pomegranate product by radiation pasteurization. J. Food Technol. 20 (3), 367-374, (June 1985).

PELLEG*, J., ZEVIN*, L., KIMMEL, G. and DAYAN, D. Recent advances in the rare earth-gallium systems (R-Ga). J. Less-Common Met. U_0 (1-2), 91-98, (Aug. 1985). "International rare earth conference, Zurich, 1985. Part 1. Proceedings".

PENG*, C.T. and BUCHMAN, O. Structure confirmation and identification by predicted retention indexes in tritium labeling. (Technical note). Int. J. Appl. Radiat. Isot. 36 (5), 414-416, (May 1985).

PENG*, C.T. and BUCHMAN, 0. Tritium exchange labeling of compounds containing _N0 _I, _C=C, and _C=0 groups. Tetrahedron Lett., 26_ (11), 1375-1378, (1985).

PINTO, H., MELAMUD, M. , KUZNIETZ, M. and SHAKED, H. Magnetic structures in the ternary RM X_ compounds

(R = Gd to Tm; M = Fe, Co, Ni, or Cu; X = Si or Ge). Phys. Rev., B 31 (1), 508*515, (1 Jan. 1985).

PLATZNER, I. Multiple ion collection in thermal ionization isotope ratio mass spectrometry of strontium. Int. J. Mass Spectrom. Ion Proc. 67 (2), 129-136, (25 Oct. 1985).

228

POLLAK*, E., BAER, M., ABU-SALBI*. N. and KOURI*. D.J. A model study of symmetric light atom transfer reactions. Chem. Phys. 99 (1), 15*33, (1 Oct. 1985).

PRI-BAR, I. and BUCHMAN, 0. 1 3 1 3

Synthesis of C-labelled propylene oxide via C-labelled 2-chloropropionlc acid and 2-chloropropanol. J. Labelled Comp. Radiopharm. 22 (12), 1227-1232, (Dec.1985).

RABINOVITCH*, A., THIEBERGER, R. and FRIEDMAN, M. Effective phaseshifts in the presence of electric fields. J. Phys., B J_8 (3), 393-399, (14 Feb. 1985).

RABINOVITCH*, A., THIEBERGER, R. and FRIEDMAN, M. Effective phaseshifts in the presence of electric fields. J. Phys., B 8 (3), 393-399, (14 Feb. 1985).

RAFAELOFF, R., TRICOT*, Y.M., NOME*, F.and FENDLER*, J.H. Colloidal catalyst coated semiconductors in surfactant vesicles. In situ generation of rhodium-coated cadmium sulfide particles in dioctadecyldimethylammonium hallde surfactant vesicles and their utilization in photosensitized charge separation and hydrogen generation. J. Phys. Chem. 89 (3), 533~537, (31 Jan. 1985).

RAFAELOFF, R., TRICOT*, Y.M., NOME*, F., TUNDO*. P. and FENDLER*, J.H. Incorporation of a recyclable surface-active electron donor in synthetic vesicles: Application to photosensitized hydrogen formation by vesicle-stabilized RJvcoated colloidal CdS particles. J. Phys. Chem. 89 (7), 1236-1238, (28 Mar. 1985).

RAIZMAN, A., BARAK, J. and SUSS, J.T. Electron-paramagnetic-resonance study of the Pd Jahn-Teller ion in CaO. Phys. Rev., B 3J. (9), 5716-5721, (1 May 1985).

RAIZMAN, A., ZAMIR, D. and COTTS*. R.M. Deuteron NMR relaxation rates in cerium deuterides. Phys. Rev., B 31 (6), 3384-3391, (15 Mar. 1985).

RAPAPORT, M.S. and ENGLER, G. The internal conversion electron counting station at the Soreq on-line isotope separator. Nucl. Instr. Meth. Phys. Res., A 236 (1), 17~19, (1 May, 1985).

RAPAPORT, M.S. and GAYER, A Decay of mass-separated Cs and Ba. Int. J. Appl. Radiat. Isot. 36 (9), 689"'697, (Sept. 1985).

RAPOPORT, E. Cubic boron nitride - A review. Ann. Chim.* Sci. Mat. H) (7), 607-638, (1985).

229

RAPOPORT, E. and NADIV*. S. Mechanochemical activation of hexagonal boron nitride and synthesis of the cubic form. J. Mater. Sci. Lett. 4i (1), 34-36, (Jan. 1985).

RAPOPORT, E., BRODHAG*. C. and THEVENOT*, F. Hot pressing of titanium nitride powders. Rev. Chim. Miner. 22 (4), 456-466, (1985).

RAVEH, A., ELDAN, M., INSPEKTOR, A. and AVNI, R. Structure of the solid pyrolysis products produced from propylene in a low-pressure inductive R.F. plasma. Carbon 23 (2), 179-184, (1985).

RON, S., SHIMA, Y. and BAER, M.. A study of light-heavy mass type molecules reacting with a solid surface. Chem. Phys. Lett. Vl_6 (5), 443-447, (17 May 1985).

ROSEN*, G., GEFEN, Y. and BARAM*, J. Multilayered compact ribbons obtained by centrifuge melt spinning. J. Mater. Sci. Lett. .4 (10), 1258-1260, (Oct. 1985).

ROSENFELD, Y. High-density properties of liquid-state theories: Physically intuitive meaning for the direct correlation functions. Phys. Rev., A 32 (3), 1834-1842, (Sept. 1985).

ROSENFELD, Y. and BLUM*, L. Statistical thermodynamics of charged objects. J. Phys. Chem. 89 (24), 5149~5151, (21 Nov. 1985).

ROTMAN*, A., COHEN, H. and MEYERSTEIN*, D. Mechanism of hydrolysis of the metal-carbon bond in gamma-hydroxy-alkyl-chromium(III) complexes. Effect of nonparticipating ligands. Inorg. Chem. £4 (24), 4158-4164, (20 Nov. 1985).

ROTTER, S., LACHISH, U., and EL-HANANY, U. Substrate preparation by a contactless mechanochemical polish. (Letter to the Editor). J. Cryst. Growth 73 (1 ), 187-189, (Oct. 1985).

SALZMANN, D., YIN*, R.Y. and PRATT*, R.H. Comparison between average-atom and detailed-configuration-type calculations of the photoionization cross section of hot and dense aluminum plasmas. Phys. Rev., A 32 (6), 3627-3638, (Dec. 1985).

SCHNECK*, R., ROKHLIN*. S.I. and DARIEL, M.P. Criterion for predicting the morphology of crystalline cubic precipitates in a cubic matrix. Metall. Trans., A J_6 (2), 197-202, (Feb. 1985).

230

SEEMAN*. P., ULPIAN*. C., GRIGORIADIS*, D., PRI-BAR, I. and BUCHMAN, 0. Conversion of dopamine D receptors from high to low affinity for dopamine. Biochem. Pharmacol. 3fJ. (1), 151-151), (1985).

SHER, A., EGER, D. and ZEMEL, A. Mercury zinc telluride, a new narrow-gap semiconductor. Appl. Phys. Lett. 46. (1), 59-->6l, (1 Jan. 1985).

SHER, A., EGER, D., ZEMEL, A., FELDSTEIN, H. and RAIZMAN, A. Properties of HgZnTe grown by LPE. In:The 1985 U.S. workshop on the physics and chemistry of mercury cadmium telluride, San Diego, California, USA, 8-9 October 1985. Extended abstracts. p.57~60.

SHER, A., EGER, D., ZEMEL, A., FELDSTEIN, H. and RAIZMAN, A. Mercury zinc telluride epilayers grown by LPE. J. Cryst. Growth 72 (1/2), 108^110, (July/Aug. 1985). "International conference on II-VI compounds, 2nd, Aussois, France, 4-8 March 1985."

SHIMA, Y. and BAER, M. A study of the parallel molecule-surface reaction HC1 + surface — > H...surface + CI: A comparison between quantum mechanical and quasi-classical trajectory results. J. Chem. Phys. 83 (10), 5250-5259, (15 Nov. 1985).

SHIM0NI, M., ROSENTHAL*, I. and BEN-HUR, E. Tritium ^ labelled chloroaluminium phthalocyanine. J. Labelled Comp. Radiopharma. 22 (8), 863-865, (Aug. 1985).

SLAMA-SCHW0K*. A., GERSHUNI*, S., RABANI*, J., COHEN, H. and MEYERSTEIN, D. An iridium-bipyridine complex as a photosensitizer for the bromide oxidation to bromine by oxygen. J. Phys. Chem. 89 (12), 2460^2464, (6 June, 1985).

SL0TKY*, D., JAEGER, Z. and ENGLMAN, R. Distribution of fragments in a series of explosions in the Rotem oil shale fields - Theory and experiment. In: Mini-symposium on explosives and blasting research, 1st, San Diego, California, USA, 31 January - 1 February 1985. Proceedings, p. 130-1H0.

S0REK, Y., COHEN, H. and MEYERSTEIN, D. Reactions of iron (II) protoporphyrin with strongly reducing free radicals in aqueous solutions. A pulse^radiolytic study. J. Chem. Soc. Faraday Trans. I 81. (1), 233~239, (Jan. 1985).

SPECTOR, N. Photoabsorption and inner shell excitation spectra in the vacuum ultraviolet. Opt. Pur. Apl. _18_ (3), 183-192, (1985).

231 •

STEINER*. J.P., FARAGGI, M., KLAPPER*, M.H. and DORFMAN*, L. Reactivity of protein histidines toward the hydrated electron. Biochemistry 2^ (9), 2139-2146, (1985).

STERN, E. and TADMOR, J. Uncertainty bands in CCDF risk curves: their importance in decision making processes. In international topical meeting on probabilistic safety methods and applications, San Francisco, California, USA, 24 February -1 March, 1985. Proceedings. ANS/ENS. Vol.1, p.22-1 - 22~9.

STRAUSS*, H.R., FRIEDLAND*, L. and KISHINEVSKY, M. Toroidally linked mirrors. Phys. Fluids 28 (12), 3591-3597, (Dec. 1985).

STRAUSS, M., AMENDT*, P., RAHMAN*, H.U. and ROSTOKER*, N. Line shifts in electron channeling radiation from lattice vibrations. Phys. Rev. Lett. 55 (4), 406-409, (22 July 1985).

STRIEM, H.L. Quantitative and qualitative aspects of the recent climatic fluctuations. Isr. J. Earth Sci. 34 (1), 47-48, (1985).

STRIEM, H.L. Evaluating water resources in the light of climatic fluctuations in Israel, In: Scientific basis for water resources management. Proceedings of a symposium held in Jerusalem, 19^23 September 1985. Ed. by M.Diskin. Israel Assoc, of Hydrology. IAHS Publ.no.153. p.411-421.

SZICHMAN, H., KRUMBEIN, A.D. and ELIEZER, S. Calculation of average degree of ionization by a comparison between TFC theory and the average atom ionization model. In: International conference on radiative properties of hot dense matter, 2nd, Sarasota, Florida, USA, 31 October-4 November, 1983. Proceedings. Ed. by Jack Davis et al. Singapore, World Scientific Publishing Co., 1985. p.572-*582.

TADMOR, J. and KOCH, J. Technical note: radiological health effects from potential accidents in small vs. large nuclear power plants. Nucl. Saf. 26 (3), 345"348, (May-June 1985).

TADMOR, J., KOCH, J. and GANTS, E. Environmental protection as a factor in reducing the radiological effects to the population due to an accident in a nuclear power plant. (Abstr. IL01). In: Waste management research abstracts no.16. International Atomic Energy Agency, Vienna, 1985. p.236. (IAEA/WMRA/16).

232

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THIEBERGER, R., FRIEDMAN, M. and RABINOVITCH*, A. Three-dimensional effective phaseshifts in the presence of electric fields (Letter to the editor). J. Phys., B JJ5 (19), L673-677, (1^ Oct. 1985).

TOBIAS, H. and SOFFER, A. Chemisorption of halogen on carbons-I. Stepwise chlorination and exchange of C-Cl with C--H bonds. Carbon 23 (3), 281-289, (1985).

TOBIAS, H. and SOFFER, A, Chemisorption of halogen on carbon-II. Thermal reversibility of CI HC1 and H chemisorption. Carbon 23 (3), 291'299, (1985).

VAINAS, B. A local corrosive breakdown of surface compensated CdS electrodes. J. Electroanal. Chem. Interf. Electrochem. 184 (1), 215^220, (8 Mar. 1985).

VULKAN, U. and TIKOCHINSKY*, G. Airborne radiometric survey in Israel. Program for regional creation of data files. Ministry of Energy and Infrastructure, Geological Survey of Israel, Jerusalem. Z.D. 109/85. (In Hebrew).

WOLF, A., WARNER*, D.D. and BENCZER-KOLLER*, N. Effective g factors and proton.-boson numbers in the vicinity of proton subshell closures. Phys. Lett., B Jj>8 (1), 7-10, (1 Aug. 1985).

YATOM, H. and RUPPIN, R. Excitation of a circular loop through a small aperture, IEEE Trans. Antennas & Prop. AP--33 (1), 10H05, (Jan. 1985).

YEHESKEL, 0. Pressure dependence of the phase transition of Si^N . (Abstract). Mater. Sci. Eng. 71 (1=-2), 371, (May 1985). "International symposium on engineering ceramics, Jerusalem, Israel, 16-20 December, 1984. Proceedings".

YEHESKEL, 0. and GEFEN, Y. The effect of the a phase on the elastic properties of

SiV. Mater. Sci. Eng. 71 (1~2), 95-100, (May 1985). "International symposium on engineering ceramics, Jerusalem, Israel, 16^20 December, 1984. Proceedings".

YEHESKEL, 0., GEFEN, Y. and TALIANKER*. M. Properties and microstructure of hot isostatically pressed

Si3N4. (Abstract). Mater. Sci. Eng. 71 (1-2), 167-168, (May 1985). "International symposium on engineering ceramics, Jerusalem, Israel, 16^20 December 1984. Proceedings".

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YELLIN, N. and SZAPIRO, S. Calculation of the partial vapor pressures of tellurium and cadmium over non-stoichiometric CdTe in the temperature range 750-1050°C. J. Cryst. Growth 73 (1), 77-82, (Oct. 1985).

YELLIN, N., ZELINGHER*, N. and BEN -.DOR*, L. Whisker growth by means of cellulose acetate membranes: NaCl and KCl. J. Cryst. Growth 71 (2), 427*432, (Mar./Apr. 1985).

YELLIN, N.f ZEMEL, A. and TENNE*, R. Electrical properties of CdTe crystals grown by VUVG from non-stoichiometric charges. J. Electron. Mater. U_ (2), 85-94, (Mar. 1985).

YIFTAH, S. A combined hydro-nuclear-solar project for electric power production. Nucl. Sci. Eng. 90 (4), 483^490, (Aug. 1985).

ZANGEN, M. and COHEN*, A. Studies on alkaline earth sulfites. 7. Hydrogen bonding and the location of hydrogen atoms in the crystal structure of CaSO . 4H20 and Ca_(S0 )250^.12H0.

5

Chem. Lett. (6), 797-800, (June 1985).

ZANGEN, M. and COHEN, A. Studies on alkaline earth sulfites. VI. Thermal dehydration of Ca(SO3)x(SOl4)1_x.i1H20.

Thermochim. Acta 85, 107M10, (1 Apr. 1985).

"European symposium on thermal analysis and calorimetry, 3rd., Interlaken,Switzerland,9-15 September 1984. Proceedings."

ZIGLER.A., LUDMIRSKY.A., L0EB,A., B0R0WITZ,J.L., ELIEZER.S., GIVON, M. GAZIT.Y., JACKEL.S., KRUMBEIN.A.D., ROSENBLUM.M. and ARAD.B.

Deposition of energy outside of the focal spot as observed on the rear surface of laser irradiated targets. Phys. Lett., A U2 (5), 223~226, (28 Oct. 1985).

234

PAPERS PRESENTED AT CONFERENCES

NATIONAL SYMPOSIUM ON PLASMA SPECTROCHEMISTRY, 1ST, JERUSALEM, ISRAEL, 2ND JANUARY 1985. GEOLOGICAL SURVEY OF ISRAEL.

INSPEKTOR, A., CARMI, U. , HORNIK, Y. and AVNI, R. The use of electrical probes for plasma diagnostics.

LORBER, A. and GOLDBART, Z. Improved analytical performance in multichannel atomic emission spectrometry by generalized internal reference procedures.

LORBER, A. and GOLDBART, Z. Analysis of solid samples in ICP-ES by direct insertion of carbon cup into the tail of the source.

1985 EUROPEAN WINTER CONFERENCE ON PLASMA SPECTROCHEMISTRY, LEYSIN, SWITZERLAND, 7"11 JANUARY 1985.

GOLDBART, Z., HAREL, A. and LORBER, A. The use of internal standard for the precise determination of neodymium in yttrium aluminum garnet.

LORBER, A. and GOLDBART, Z. Analysis of solid samples in ICP-ES by direct insertion of carbon cup into the tail of the source.

LORBER, A. and GOLDBART, Z. Improved analytical performance in multichannel analysis by compensation for nonrandom fluctuations.

1985 ANNUAL JOINT MEETING OF THE AMERICAN PHYSICAL SOCIETY AND THE AMERICAN ASSOCIATION OF PHYSICS TEACHERS, TORONTO, ONTARIO, CANADA, 21-24 JANUARY, 1985.(Bull.Am.Phys.Soc. 30(1), 43, (Jan.1985)).

ENGLMAN, R. and ZGIERSKI*. M.Z. Total Hamiltonian formulation of transition rates.(Abstr. GE14).

ENGLMAN, R., JAEGER, Z. and LEVI, A. Percolation theoretical approach to fragmentation in solids. (Abstr. GE13).

RUPPIN, R. and ENGLMAN, R. Additional boundary condition (ABC) independence in the optical properties of nonlocal dielectrics. (Abstr. GE10).

235-

THE NUCLEAR SOCIETIES OF ISRAEL ANNUAL MEETING, BEER-SHEVA, 6"7 FEBRUARY, 1985. TRANSACTIONS. BENr-.GURION UNIVERSITY OF THE NEGEV. VOL.12.

ALFASSI*, 2. and ROTEM, H. Determination of penetration depth of airborne iodine on granular beds under dynamic flow conditions, p.68*73.

BAR-NOY, T. A systematic approach to shielding and activation analysis. p. 176=180.

BEN-SHACHAR, B . f GERMAN, U. , LEICOTER, Y. and VJEISER, G. Improving the fad ing of CaF :Dy c a r d s by changing the r e a d i n g t empera tu re p r o f i l e , p . 117~122.

BENnSHACHAR, B., GERMAN, U., WEISER, G. and LEICHTER, Y. The energy dependence of CaF :Tm. p. 113-116.

GALPERIN*. A., SEGEV*, M., KARNI, Y. and GOLDFELD*. A. BGUCORE n a neutronic package for PWR fuel management, p. 17^20.

GOLDSTEIN, M. P e r t u r b a t i o n c a l c u l a t i o n s u s i n g the r e c u r s i v e d i s c r e t e - o r d i n a t e s (RSN) method, p . 3^3,1.

GOLDSTEIN, M. and KINROT, A. Direct applications of the recursive discrete-ordinates (RSN) method, p. 38-41.

GREEN, M., PRAGER, A. and RIKLIS, E. Radioprotection and DNA repair: II. The effect of WR-2721 and cysteamine on formation and repair of DNA strand breaks, p. 103-106.

GREENSPAN, E. and KINROT, A. Novel concepts of fusion reactor blankets and shields, p. 163~165.

KOL, R., MARKO, R. and RIKLIS, E. Protection and sensitization of living cells to radiation through the involvement of bio«chemical pathways, p. 102.

MARGALIOT, M., SCHLESINGER, T., LUBIN, E. and FRIEDLAND*. S. In vivo Xs-.ray fluorescence measurements of thyroidal iodine content, p. 88-91.

MUNITZ, A., LIVNE, Z. and GERTNER*, I. + +

Blistering in commercial aluminum alloys via H and Ar ion implantation, p. 108M112.

236

REGEV, D. and GREENSPAN, E. P o s s i b i l i t i e s for t he des ign of p r e s s u r e _ tube r e a c t o r s wi th b a t c h n r e f u e l i n g , p . 29" ,33.

RON, S. and BAER, M. Removal rates calculation of radioactive compounds in the containment, following an hypothetical accident, p. 68-73.

RON, S. and REGENSTREIF, M. Large differences in the consequences results obtained from the CRAC computer code and its latest version CRAC 2. p. 81-83.

SAPHIER, D. An improved pressurizer model for DSNP. p. 153~158.

SAPHIER, D. and KALFELZ*, J. The sensitivity of the pressurizer response to PORV setting under simulated accident conditions, p. 148^152.

SAPIR, J., COHEN, H. and ALFASSI*. Z.B. The radiolysis of CFC1 and of its mixtures with RH substrates.

p. 126-129.

SCHLESINGER, T . , IZAK-BIRAN, T . , WEINGARTEN, R. , EVEN, 0 . , SHAMAI, Y. and ISRAELI, M,

210 Transfe r c o e f f i c i e n t s of Po from l i v e s t o c k feed to meat and eggs . p . 201-203.

SCHNEIDER, A. and SHVARTS, D. Potential of very compact tokamak reactors with resistive magnets. p. 166-167.

SHAYER, Z. The albedo boundary condition in different formulations of the neutron transport equation, p. 21-24.

SZABO, J. Application of U.S. fission power experience to fusion power. p. 160^162.

TADMOR, J. and KOCH, J.

Potential accidents in small nuclear power plants cause relatively less radiological health effects to the population than larger plants, p. 74-80.

VARTSKY, D., SHAMAI, Y., DUCHAN, R., KL0PFER, Y. and GOLDBERG, M. Investigation of pulse risctimes in CdTe radiation detectors, p. 199-200.

237

VULKAN, U. and BEN^HAIM*, Y. Assay-system design for bore-hole logging of uranium, p. 61-63.

TOPICAL AMERICAN PHYSICAL SOCIETY CONFERENCE ON ATOMIC PROCESSES IN HIGH TEMPERATURE PLASMAS, 5TH, PACIFIC GROVE, CALIFOP.NIA, USA, 25^28 FEBRUARY 1985.

ZIGLER, A., JACKEL, S., LUDMIRSKY, A., KLAPISH, M. and MEROZ, E. The use of unresolved transition arrays for diagnosis of hot plasma.

JOURNEES DES ACTINIDES, 15EMES, LIEGE, BELGIUM, 26~27 FEBRUARY 1985. KUZNIETZ, M., BURLET*. P., ROSSAT-MIGNOD*, J. and VOGT*, 0. The magnetic phase diagram of the UAS Se system in zero magnetic field studied by neutron diffraction from single crystals n preliminary results. (Paper 1.1).

CONVENTION OF ELECTRICAL AND ELECTRONICS ENGINEERS IN ISRAEL, 11TH, INSTITUTE OF ELECTRICAL AND ELECTRONICS ENGINEERS, TEI.aAVIV, ISRAEL, 25-28 MARCH 1985.

MARELI, M., MITELMAN, Y. and BOGER, Z. Remote control and collection of control board information.

1985 MARCH MEETING OF THE AMERICAN PHYSICAL SOCIETY, BALTIMORE, MARYLAND, USA, 25^29 MARCH 1985. ABSTRACTS. (Bull. Am. Phys. Soc. 30 (3), (Mar. 1985).

BARAK, J., SUSS, J.T. and RUPPIN, R. FMR study of the dispersion relations of the magnetostatic modes in a YIG film. (Abstr. NP9). p. 615.

ISRAEL PHYSICAL SOCIETY 1985 ANNUAL MEETING. BEN*--GURI0N UNIVERSITY OF THE NEGEV, BEER-SHEVA, 3 APRIL 1985. PROGRAM AND ABSTRACTS. (Bull. isr. Phys. Soc, 1985).

BERANT, Z., MOREH, R., TENENBAUM, J. and WOLF, A. Observation of A 1+ state at 5210 KeV in Ca. (M - 3). p. 50.

DARIEL, M.P., KONCZYKOWSKI*, M. and LORENZELLI*, N. Solid-state amorphisation in Y*Cu thin film multilayers. (A - 7). p. 19.

GOLUB*. I., SHUKER*, R. and EREZ, G. Stimulated blue shifted emission near D transition in sodium. (0 - 2). p. 61.

HAZAK, G., STRAUSS, M. and OREG, J . Strong laser atom in terac t ion in the presence of jumpfprocess type noise - The Bourret approach. (R - 1 ) . p. 71.

KAHANE, S. and WOLF, A. Photofission of ^ U with neutron capture gamma-rays. (M - 2 ) . P. 19.

238

LOTEM, H., AMIT, M., LAVI, S., LIRAN, Y. and EREZ, G. Interference between broadened sidebands of pulse amplified phase-modulated CW dye laser. (0 » 4), p. 63.

LOTEM, H., LAOR, U. and BLUMENFELD, M. A polarization prism based on double reflection. (0 - 3 ). p. 62.

MINTZ, M.H. and SHAMIR, N. Time-of-flight analysis of direct recoils (TOF-DR) - A new surface technique. (K). p. 39.

MOREH, R. and SHAHAL, 0. Study of the orientation of adsorbed N O molecules using nuclear resonance fluorescence. (K - 1). p. 40.

PINTO, H., MELAMUD, M., KUZNIETZ, M. and SHARED, H. Magnetic structures in the ternary RM X compounds. (R = Gd to

Tm; M = Fe, Co, Ni, or Cu; X = Si or Ge). (N - 9). p. 59.

RAIZMAN, A., ROTTER, S., LACHISH, U. and EL-HANANY, U. EBIC measurements of lead salts injection lasers. (K - 6). p. 45.

STRAUSS, M., AMENDT*, P., RAHMAN*, H.U. and ROSTOKER*. N. X-ray spectroscopy from relativistic beams channeling in crystals. ( 1 * 1 ) . p. 34.

STRAUSS, M., AMENDT*, P., and RAHMAN*, H.U. Magnetic surface instabilities in plasmas. (R * 5). p. 78.

1985 SPRING MEETING OF THE AMERICAN PHYSICAL SOCIETY, CRYSTAL CITY, VIRGINIA, USA, 24-27 APRIL 1985. ABSTRACTS. (Bull. Am. Phys. Soc. 30. CO, April 1985).

IVRI, J., BERGEMAN*, T. and METCALF*, H.J. Sodium stark photoionization line widths and level crossing effects. (Abstr. DH6). p. 749.

MCNICHOLL*, P . , IVRI, J . , LIU*, J . fcY. , BERGEMAN*, T. and METCALF*, H.J . Static electric field ionization of sodium. (Abstr. DH12). p. 750.

UNESCO INTERNATIONAL SYMPOSIUM ON FUNDAMENTAL ASPECTS OF APPLIED ELECTROCHEMISTRY, KIRYAT-ANAVIM, 6~8 MAY 1985. ISRAEL NATIONAL COUNCIL FOR RESEARCH AND DEVELOPMENT.

SOFFER, A. Porous carbon electrodes-choice, characterization and useful applications.

239

CONFERENCE OF THE ISRAEL SOCIETY FOR ELECTRONIC MICROSCOPY, JERUSALEM, 7TH MAY 1985.

VENKERT, A., ATZMONY, U. and DARIEL, M.P. Solid-state amorphization in Cu^Ho evaporated thin film multilayers.

STATISTICAL MECHANICS MEETING, 53RD, RUTGERS UNIVERSITY, NEW BRUNSWICK, NEW JERSEY, USA, 9M0 MAY 1985.

ACHIAM, Y. Critical dynamics of fractal lattices.

MEETING OF THE ELECTROCHEMICAL SOCIETY, 167TH, TORONTO, ONTARIO, CANADA, 12-17 MAY 1985. ABSTRACTS. (J. Electrochem. Soc. J_32. (3), Mar. 1985).

KALISKY, Y., REISFELD*, R. and TZEHOVAL*, H. ?+ 3+

Mechanism of energy transfer between UO and Ho and

nonradiative relaxation in a donor and acceptor system in amorphous media. (Abstr. 439). p. 124C.

INTERNATIONAL CONFERENCE ON NUCLEAR DATA FOR BASIC AND APPLIED SCIENCE, SANTA FE, NEW MEXICO, USA, 13*"17 MAY, 1985.

WOLF, A., BERANT, Z., WARNER*, D.D., GILL*, R.L., HILL*, J.C., WOHN*, F.K., SISTEMICH*, K., MENZEN*, G. and CHEIFETZ, E. Magnetic moments of excited states in neutron-rich nuclei.

CONFERENCE ON LASERS AND ELECTRO^OPTICS (CLEO 85), BALTIMORE, MARYLAND, USA, 21-24 MAY, 1985.

AZAR, Z., LOEBENSTEIN, H.M., AZOULAY, E., HALAVEE, U., TAMIR, M. and TUR*. M. Two-frequency wave propagation in the atmosphere: Intensity covariance and aperture averaging. (Poster paper WM2).

JACKEL, S., LALLUZ, R., LUDMIRSKY, A., ZENTNER, A., BOROWITZ, A., GIVON, M. , ARAD, B. and GAZIT, Y. Multi-pass amplifiers for high-power laser systems.

KALISKY, Y. and WILLIAMS*, D.J. Excimer laser photolysis studies of photoinduced aggregation in polymers containing spiropyran units. (Poster paper WC3).

AMERICAN SOCIETY FOR MASS SPECTROMETRY (ASMS) ANNUAL CONFERENCE ON MASS SPECTROMETRY AND ALLIED TOPICS, 33RD, SAN DIEGO, CALIFORNIA, USA, 26-31 MAY 1985.

KARPAS, Z., STEVENS*, W.J., BUCKLEY*, T.J. and METZ*. R. The gas-phase ion chemistry and proton affinity of methyl isocyanate, methyl isothiocyanate, and methyl thiocyanate. p.300-301.

240

EUROPEAN CONFERENCE ON CLINICAL ONCOLOGY AND CANCER NURSING, 3RD, 16^20 JUNE, 1985.

RIKLIS, E. Adjuvant radiotherapy, radioprotection, photosensitization and DNA repair modification as modality for cancer therapy.

ISRAEL CONFERENCE ON MECHANICAL ENGINEERING, 19TH, BEERSHEVA, ISRAEL, 19-20 JUNE, 1985.

BARNEA, Y. and SHAI*, I. Heat transfer coefficient in opposing mixed convection part 2: Experimental results.

SHAI*, I. and GILAD, I. Heat pipe with radial fins.

INTERNATIONAL SYMPOSIUM ON PLASMA CHEMISTRY, 7TH, (ISPC-7), EINDHOVEN, NETHERLANDS, 1 -5 JULY, 1985.

AVNI, R. and SPALVINS*, I. Nitriding mechanisms in Ar+N2, Ar+N2+H2 and Ar+NH3 mixtures in dc glow discharges at low pressure (<1OTORR).

AVNI, R., CARMI, U. and INSPEKTOR, A. Homogeneous reactions in dc glow, radio-frequency and microwave discharges.

CARMI, U., INSPEKTOR, A., MAYO, N. and AVNI, R. Massiispectrometric investigation of homogeneous reactions in the microwave nitriding plasma.

KHAIT*, Y.L., CARMI, U., INSPEKTOR, A. and AVNI, R. The effect of plasma-substrate interaction on the promotion of chemical bonding between thin film and substrate.

INTERNATIONAL CONFERENCE ON NUMERICAL METHODS IN LAMINAR AND TURBULENT FLOW, SWANSEA, USA, 9^12 JULY 1985.

GEYER, I., APELBLAT*, A. and BAR-ZIV, E. Reacting turbulent flow produced by two concentric tubes of finite wall thickness.

ACTA ENDOCRINOLOGICA CONGRESS, XV, HELSINKI, FINLAND, 5~9 AUGUST 1985. BOOK OF ABSTRACTS.

FREUD, A., BEDRAK*,'E. and SOD-MORIAH*, U.A. Noenatal, low dose Y - irradiation induced hormonal changes in mature female rats. (Abstr.289).

241

CRYOGENIC ENGINEERING CONFERENCE AND INTERNATIONAL CRYOGENIC MATERIALS CONFERENCE, (CEC/ICMC 85), CAMBRIDGE (BOSTON) MASSACHUSETTS, USA, 12*16 AUGUST 1985.

KATZ, Y., BUSSIBA, A. and MATHIAS, H. Mechanical behavior and fatigue in polymeric composites at low temperatures. (Oral session). (Bx - 2).

INTERNATIONAL CONGRESS ON QUANTUM CHEMISTRY, 5TH, MONTREAL, QUEBEC, CANADA, 18-24 AUGUST 1985. ABSTRACTS.

LAST, I. and BAER, M. Examination of the hopping model for non-adiabatic electronic transitions in atom-diatom collisions. (Abstr.55~C). P.32H.

LAST, I. and BAER, M. Analytical fitting of DIM-3C potential energy surfaces of HX„ (X = CI,Br,I) systems. Trajectory calculations. (Abstr.55~E). p.326.

INTERNATIONAL CONFERENCE ON MAGNETISM (ICM'85), SAN FRANCISCO, CALIFORNIA, USA, 26^30 AUGUST 1985.

KUZNIETZ, M., BURLET*, P., ROSSAT-MIGNOD*, J. and VOGT*, 0. Neutron diffraction investigation of commensurate and incommensurate phases in UAS Se single crystals. (5Pc 13).

NATO ADVANCED RESEARCH WORKSHOP ON HOMOGENEOUS AND HETEROGENEOUS PHOTOCATALYSIS, MARATEA, ITALY, 1r7 SEPTEMBER 1985.

HARUVY, Y., RAFAELOFF, R. and RAJBENBACH, L.A. Radiolytic methods of preparation of colloidal and heterogeneous redox catalysts and their application in lights-induced H generation from water.

ACTINIDES 85, AIX EN PROVENCE, FRANCE, 2~6 SEPTEMBER 1985. COMMISSARIAT A L'ENERGIE ATOMIQUE. (POSTERS).

BURLET*, P., QUEZEL*, S., KUZNIETZ, M., BONNISSEAU*, D., ROSSAT-MIGNOD*, J., SPIRLET*, J.C., REBIZANT*, J. and VOGT*, 0. Neutron diffraction study of Np As single crystal. (32B-150). p. 70.

DAYAN, D., DARIEL, M.P. and DAPHT, M. Metastable s t ruc tures in d i lu te uranium-gallium a l l oys . (1D-7). p. 95.

GAL, J.,PINTO, H..FRED0, S..MELAMUD, M..SHAKED, H.,CACIUFFO*, R., LITTERST*, F.J., ASCH*, L., POTZEL*, W. and KALVIUS*, G.M. Crystalline field effects in Np-intermetallics (6B-28). p. H4.

KIMMEL, G., LANDAU, A., SARIEL, J. and ADMON, U. Phase transformations in dilute U-Ti alloys. (17D-111). p. 111.

242

KUZNIETZ, M., BUBLET*, P., ROSSAT-MIGNOD*, J. and VOGT*, 0. The magnetic phase diagram of the UAs Se system in zero magnetic field studied by neutron diffraction from single crystals. (14B*62). p. 52.

ZANKERT*, J.P., POTZEL*, U., MOSER*. J..P0TZEL*. W.,OBENHUBER*,Th., KALVIUS*. G.M., GAL, J., BENEDICT*, U. and SPIRLET*, J.C. Volume compressibilities of some neptunium intermetallics. (7B-29). p. 15.

EUROPEAN NUCLEAR MEDICINE CONGRESS, LONDON, UK, 3-6 SEPTEMBER 1985. SCIENTIFIC PROGRAMME.

IAINA, A., WEININGER, J. and ABRASHKIN, S. Cortex and medullary proton NMR in gentamycin and glycerol induced acute renal failure in rats.

LAVIE, E., BOAZI, M., WEININGER, J., BARTAL, A.H. and HIRSHAVT*. Y. Labeling of human anti-sarcoma monoclonal antibody with In-

and Ga*67.

INTERNATIONAL SYMPOSIUM ON MASS SPECTROMETRY, 10TH, SWANSEA, WALES, UK, 9-13 SEPTEMBER, 1985.

PLATZNER, I. Isotopic analysis of strontium using multiple collection mass-spectrometry.

INTERNATIONAL SYMPOSIUM ON RADIO-PHARMACOLOGY, JJTH, BANFF, ALBERTA, CANADA, llrlH SEPTEMBER 1985.

BOAZI, M., LAVIE, E., WEININGER, J., BARTAL, A.H. and HIRSHAVT*, Y. In and Ga labelling of antisarcoma and anti-connective tissue monoclonal antibodies.

COLLOQUIUM SPECTROSCOPICUM INTERNATIONALE, 24TH, GARMISCH-PARTENKIRCHEN, F.R. GERMANY, 15~21 SEPTEMBER, 1985. (CSI-.XXIV).

BRENNER*, I.B., LORBER, A. and GOLDBART, Z. Trace element analysis of silicate rocks by direct insertion of a graphite cup into an ICP.

ISRAEL SOCIETY OF CHEMISTRY ANNUAL MEETING, 51 ST, HAIFA, ISRAEL, 9-10 OCTOBER 1985. PROGRAM.

LIFSHITZ*, C., PERES*, T., OHMICHI*, N., PRI^BAR, I. and RADOM*, L. Is propylene oxide a case of non^ergodic behavior? p. 93.

PLATZNER, I. Thermal ionization isotope ratio analysis with a multiple collection detection system, p. 39.

243

PRI^BAR, I. and BUCHMAN, 0. Transfer hydrogenolysis of organic halides catalyzed by tetrakis (triphenyl phosphine) palladium (0). p. 72.

SEMBIRA, A.N. Thermal analysis of borosilicate glass, p. 55.

CONGRESS OF THE INTERNATIONAL SOCIETY FOR LASER SURGERY, 6TH, JERUSALEM, ISRAEL, 13~18 OCTOBER 1985. (ABSTRACTS).

BENrrHUR, E. and ROSENTHAL*, I. Phthalocyanines - a new class of photosensitizers for photodynamic therapy of cancer, (p. 46 in program).

BORNSTEIN, A. and BOEHM, L. Step-index chalcogenide glass fibers, p. 4.

GABAY, S., BEN-SIRA*, I. and COHEN*, S. Copper vapour laser-possible clinical applications, p. 63.

GILER*, S., KAPLAN*, I., KAGAN, J., LOTEM, H., DIKMAN, I., SAGIE, D. and LEVIN, L.A. Experimental investigation of the application of holmium laser on solid organs, p. 47.

INTERNATIONAL CONFERENCE ON NUCLEAR TECHNOLOGY TRANSFER (ICONTTr-.HI), 3RD, MADRID, SPAIN, 14-19 OCTOBER, 1985.

YIFTAH, S. The user's perspective in nuclear technology transfer.

YIFTAH, S. Nuclear fuel cycle technology transfer.

OPTICAL SOCIETY OF AMERICA ANNUAL MEETING, WASHINGTON, D.C., USA, 14-18 OCTOBER 1985. SUMMARIES OF PAPERS. (J. Opt. Soc. Am. A 2 (13), Dec. 1985).

LOTEM, H., KAGAN, J., SAGIE, D. and LEVIN, L.A.

60-W 2.06-p M Ho3+: YLF laser. (Abstr. PDP3). p. P107.

AMERICAN COLLEGE OF RADIOLOGY CONFERENCE ON CHEMICAL MODIFIERS OF CANCER CLEARWATER, FLORIDA, USA, 20~24 OCTOBER 1985.

KOL, R., MARKO, R. and RIKLIS, E. Cellular levels to NAD , controlled by nicotinamide, modify the response of repair proficient cells to radiation. p.8-=l6.

RIKLIS, E., PRAGER, A., GREEN, M. and MINSBERG, M. DNA repair synthesis and rejoining of strand breaks is favourably affected by WR-2721 in preference to cysteamine. p.7"M.

•244

SYMPOSIUM ON SEPARATION SCIENCE AND TECHNOLOGY FOR ENERGY APPLICATIONS, KNOXVILLE, TENNESSEE, USA, 20^24 OCTOBER, 1985.

KORESH, J.E. and SOFFER, A. The effect of adsorption on the gas permeability through the carbon molecular sieve membrane.

OREN, Y., ABDA, M. and SOFFER, A. Removal of mercury from aqueous solutions by electrodeposition on fibrous carbon electrodes.

SOFFER, A. and OREN, Y. Purification of aqueous suspensions from colloidal particles by electroadsorption on porous carbon electrodes.

LASER INTERACTION AND RELATED PLASMA PHENOMENA, MONTEREY, CALIFORNIA, USA, 28 OCTOBER - 1 NOVEMBER 1985.

ELIEZER, S., TAJIMA*, T. and ROSENBLUTH*. M.N. High intensity particle beams for a muon-catalyzed fusion-fission reactor.

ELIEZER, S., HORA*, H., LUDMIRSKY, A., LOEB, A., ARAD, B., B0R0WITZ, A., GAZIT, Y., JACKEL, S., KRUMBEIN, A.D., SALZMANN, D., SZICHMAN, H., GIVON, M. and ZIGLER, A. Double layers in laser produced plasmas.

LOEB, A., ELIEZER, S., ZIGLER, A., ARAD, B., LUDMIRSKY, A.,GAZIT, Y., JACKEL, S., KRUMBEIN, A.D., B0R0WITZ, J.L., GILATH, I., SZICHMAN, H. and GIVON, M. The evolution of strong shock waves produced by a trapezoidal laser pulse.

ANNUAL MEETING OF THE DIVISION OF PLASMA PHYSICS, AMERICAN PHYSICAL SOCIETY, SAN DIEGO, USA, 4- 8 NOVEMBER 1985. (Bull.Am.Phys.Soc. 30 (9), (Oct.1985)).

KRUMBEIN, A.D., SALZMAN, D. and SZICHMAN, H. Radiative transport and preheat calculations of laser irradiated targets. (Abstr.8Q28). p. 1601.

LOEB, A. and FRIEDLAND*, L. Autoresonance laser accelerator. (Abstr. 8S33). p. 1615.

LUDMIRSKY, A., GIVON, M., GAZIT, Y. , ELIEZER, S., JACKEL, S., LOEB, A., BOROWITZ, A., KRUMBEIN, A. and ZIGLER, A. Measurement of picosecond instabilities in laser plasmas. (Abstr. 6Q21). p.1528.

STRAUSS*, H.R., FRIEDLAND*, L. and KISHINEVSKY, M. Miramaks and ICRF stabilized toroidal mirrors. (Abstr. 9S24). p. 1635.

245

ZIGLER, A., LUDMIRSKY, A., BOROWITZ, J.L., GIVON, M., GAZIT, Y., JACKEL, S., LOEB, A., KRUMBEIN, A.D., KISHINIEWSKY, M. and ARAD, B. Shock velocity measurements for pressures from 0.5 to 3.5 M bar in laser irradiated targets. (Abstr. 6Q22). p. 1528-29.

ZIGLER, A., LUDMIRSKY, A., LOEB, A., BOROWITZ, J.L., GIVON, M., GAZIT, Y., JACKEL, S., KHISHINIEWSKY, M., KRUMBEIN, A. and ARAD, B. Lateral energy transport As observed on the rear surface of laser irradiated targets by a backlighting technique. (Abstr. 9S1). p. 1631-

INTERNATIONAL SYMPOSIUM ON EMERGENCY PLANNING AND PREPAREDNESS FOR NUCLEAR FACILITIES, ROME, ITALY, 1-8 NOVEMBER, 1985. INTERNATIONAL ATOMIC ENERGY AGENCY. EXTENDED SYNOPSES.

GONEN, Y.G. Development of emergency response plans in Israel. (IAEArSM^280/89). p.llOMll.

TADMOR, J., KOCH, J. and GANTS, E.

Environmental protection as a factor in reducing the radiological effects to the population due to an accident in a nuclear power plant. (IAEA-.SM.-.280/16P). p.25r26.

U.S. - ISRAELI WORKSHOP. ANNUAL MEETING OF THE AMERICAN PHYSICAL SOCIETY, DIVISION OF PLASMA PHYSICS, SAN DIEGO, CALIFORNIA, USA, 1-8 NOVEMBER 1985.

ARAD, B., BOROWITZ, J.L., ELIEZER, S. GAZIT, Y., LUDMIRSKY, A., ZIGLER, A., GIVON, M. , JACKEL, S., LOEB, A., KISHINIEWSKY, M. and KRUMBEIN, A.D. Recent plasma experiments carried out in the laser laboratory of Soreq.

CONFERENCE ON TURBULENCE AND DIFFUSION, BOULDER/DENVER, COLORADO, USA, 12-15 NOVEMBER, 1985. AMERICAN METEOROLOGICAL SOCIETY. EXTENDED ABSTRACTS.

SKIBIN, D., KAIMAL*, J.C. and GAYNOR*, J.E. Could the vertical velocity explain discrepancy between theory and measurements of air pollution? p. 11^13.

WORLD CONGRESS ON DESALINATION AND WATER RINSE, 2ND, BERMUDA, WEST INDIES, 17-21 NOVEMBER 1985.

KATZ, M.G., and BARUCH, G. New insights into the structure of microporous membranes obtained using a new evaluation method.

NATIONAL VACUUM SYMPOSIUM, 32ND, HOUSTON, TEXAS, USA, 18~22 NOVEMBER 1985. AMERICAN VACUUM SOCIETY.

INSPEKTOR, A., CARMI, U., RAVEH, A., KHAIT*, Y. and AVNI, R. Deposition of pyrocarbon in low temperature environment.

INSPEKTOR, A., CARMI, U. and AVNI, R. Low temperature deposition of silicon carbide (SiC) and silicon nitride (SiN) coatings by the low pressure r.f. plasma technique.

216

INTERNATIONAL CONFERENCE ON USERS, 8TH, LAS VEGAS, NEVADA, USA, 2r6 DECEMBER, 1985.

RAM, V., TSORY, E., BENDEC, F. and KOHN, G. CO laser welding applications.

SEMINAR ON PRACTICES FOR RADIATION STERILIZATION OF MEDICAL SUPPLIES SUITED TO THE UPGRADING OF LOCAL HEALTH-CARE SERVICES IN AFRICA AND THE MIDDLE EAST, NAIROBI, KENYA, 2"-6 DECEMBER 1985.

EISENBERG, E. Radiosterilization of bacteriological culture media and diagnostic kits.

OPTICAL FIBER SOURCES AND DETECTORS CONFERENCE, CANNES, FRANCE, 3 6 DECEMBER 1985. (CONF. A587).

ROTTER, S. Pb-salt laser light sources in the long wavelength range.

OPTICS IN ENGINEERING MEASUREMENT CONFERENCE, CANNES, FRANCE, 3-6 DECEMBER 1985. (CONF. B599).

KAFRI, 0., GLATT, I., KEREN, E. and LIVNAT, A. Novel applications of MTF measurements in engineering using Moire deflectometry.

ISRAEL MATERIALS ENGINEERING CONFERENCE, 3RD, HAIFA, ISRAEL, 10-11 DECEMBER 1985. PROGRAM AND ABSTRACTS.

ABRAMOV, E. and ELIEZER*, D. Hydrogen trapping due to stress field around volume imperfections in iron based alloys. (Abstr, 3.1.9 in Hebrew).

ABRAMOV, E., RAVEH, A., HERRMANN, B. and RABINOVITZ, E. Long time resistance of joining of aluminum plates by epoxy resin. (Abstr. 2.3.3 in Hebrew).

AZOULAY, M., GAFNI, G. and ROTH*, M. Optical germanium crystal growth and characterization. (Abstr. 7.1.5).

BEN HAIM, M. Cathodic protection of AISI 1)30 in an atmosphere of oxidizing ions and nitric acid. (Abstr. 2.1.3 in Hebrew).

BUSSIBA, A., KUPIETZ, M. and KATZ, Y. Fracture morphology in graphite or aramid reinforced polymeric composites. (Abstr. 9.3.2 in Hebrew).

DADON, D., YEHESZCKEL, 0. and GEFEN, Y. The effect of outgassing on the properties of 304L S.S. formed by H.I.P. (Abstr. 4.3.3 in Hebrew).

217

DAYAN, D. and DARIEL, M.P. Phase transformations in uranium-galium alloys. (Abstr. 2.2.3 in Hebrew).

ELGAT, Z. Structure of the first order incoherent twin in Ge by high resolution electron microscopy. (Abstr. 3.1.10).

GANOR, M., GEFEN, Y. and PELEG*, J. Properties of silicon carbide-reinforced iron composites. (Abstr. 3.1.1 in Hebrew).

GEFEN, J. and KLIMKER, H. Rapid solidification and crystallization of RE-Cu. (Abstr. 6.2.2 in Hebrew).

GILAD, A. and KATZ, Y. Local mechanical behaviour of hydrogenated ASS in multi^axial stressing. (Abstr. 7.^.8 in Hebrew).

INSPECTOR, A., RAVEH, A., WEIZMAN, J., CARMI, U. and AVNI, R. SiC coating on stainless steel by cold plasma spray. (Abstr. 5.2.3 in Hebrew).

JAEGER, Z., ENGLMAN, R. SPRECHER, A. and REINGOLD*. E. Statistical analysis of fragmented solids by use of computational geometry. (Abstr. 3.1.15).

KATZ, Y., BUSSIBA, A., KUPIETZ, M. and TOMER, A. Transient behaviour in plastic flow in compression-ductility aspects. (Abstr. 7.^.5 in Hebrew).

KLIMKER, H. and GEFEN, Y. Evaluation of sintering process by ultrasonic sound waves. (Abstr. 7.3.3 in Hebrew).

LANDAU, A., KIMMEL, G. and TALIANKER*, M. Decomposition of AS-quenched uranium^S at % titanium alloy. (Abstr. 2.2.2.).

MATHIAS, H., TOMER, A., BUSSIBA, A. and KATZ, Y. Blisters in steel - a hydrogen attack phenomenon. (Abstr. 2.1.1 in Hebrew).

PELLEG*. J., ZEVIN*. L., KIMMEL, G. and DAYAN, D. Ordering of Ga pairs in RGa_ (R=light rare earth element) type compounds. (Abstr. 2.2.1).

248

SHILO, K. and ROSENBERG, A. Holographic N.D.T. - Soreq 1985. (Abstr. 7.2.8 in Hebrew).

SHILO, K., NOTER, Y. and SAYA, A. Optical characterization of materials in the infra-red region. (Abstr. 7.2.9 in Hebrew).

SIMCA, F., STERN, A. and ELIEZER*. D. Hydrogen etnbrittlment of austenitic stainless steel welds. (Abstr. 8.1.4 in Hebrew).

STERN, A., KATAMIAN*, D. and WEATHERLY*. G.C. Hydrogen depth profiling in Zr-2.5 wt.? Nb alloy. (Abstr. 9.2.4).

STERN, A., KNEIS*, H.A. and WEATHERLY*, G.C. Thermotransport of hydrogen in Zr"2.5 wt.% Nb alloy. (Abstr. 9.2.3).

YEHESKEL, 0. and GEFEN, Y. Phase transition in silicon nitride. (Abstr. 9.1.2 in Hebrew).

ZILBER, R. Personal micro-computer in the N.D.T. laboratory. (Abstr. 7.2.3 in Hebrew).

ZILBER, R. Ultrasound NDT of composite materials. (Abstr. 7.2.4 in Hebrew).

FRITZ HABER SYMPOSIUN ON METHODS OF LASER SPECTROSCOPY, REHOVOTH AND EIN BOKEK, DEAD SEA, ISRAEL, 16-20 DECEMBER 1985. PROGRAM AND ABSTRACTS.

LIU*, J.-Y., MCNICHOLL*, P., IVRI, J., BERGEMAN*. T. and METCALF*, H.J. Interference narrowing at crossings of sodium stark resonances. p. 44.

>

249

AUTHOR INDEX

Abda, M. 134

Abe, K. 203

Abramov, E. 83, 87

Abrashkln, S. 161, 164, 166

AbuSalbi, N. 8

Achiam, Y. 6, 7, 8

Adam, G. 166, 204, 205

Admon, U. 106

Agam, S. 85

Aharonovitz, R. 94, 105

Alfassi, Z. B. 11, 38, 139, 173

Amendt, P. 72

Amir, S. 181, 182

Amit, M. 49

Apelblat, A. 14

Appelbaum, G. 51

Arad, B. 44, 49

Arie, S. 88

Ashkenazi, B. 196

Atzmony, U. 100

Avida, R. 200

Aviram, I. 7

Avni, R. 43, 44, 96, 97

Azar, Z. 51, 52

Azoulay, E. 51, 52, 57, 58

Azoulay, M. 91, 93

Azran, J. 145, 146

Baer, M. 8, 9, 11, 38

Band, Y. B. 195

Barak, D. 206

Baram, J. 77, 84

Barnea, Y. 198, 201

Bar-Noy, T. 45

Bar-Shalom, A. 14, 41

Barton, S. S. 98

Bar-Ziv, E. 12, 14, 131, 132

138, 192

Bashary, Y. 179

Behar, D. 130

Ben Dor, L. 106

Ben-Haim, M. 84, 100, 202

Ben-Halm, Y. 168

Ben-Hur, E. 155, 156, 157

Ben Hur, N. 130

Ben-Reuven, A. 13

Ben-Shachar, B. 175, 176

Ben-Sira, I. 168

Benczer-Koller, N. 112

Bendec, F. 81

Berant, Z. Ill

Bergeman, T. 70, 71

Bettelheim, A. 133

Blderman, S. 90, 105

Birenbaum, Y. Ill

Blum, L. 3

Blumenfeld, M. 199

Boehm, L. 72, 88, 89

Boger, Z. 202

Bonnlsseau, D. 65

Bornsteln, A. 72, 88, 89

Borowitz, J. L.

(Borowitz, A.) 44, 49

Branover, H. 33

Braun, A. 161, 164

Braun, G. 131

Brenner, I. B. 135, 138

Broitman, F. 133

Buchman, 0. 143, 145, 146, 147, 150

Buckley, T. J. 126

Burlet, P. 64, 65, 66, 67

253

Burshtein, Z. 90

Calaf, M. 182

Canfi, A. 144, 145, 149, 150

Caras, I. 198

Carml, U. 43, 44, 96, 97

Cannichael, A. 123, 156

Caspi, D. 145

Chavet, I. 189

Chayoth, R. 149

Cheifetz, E. 103

Chin, T. 195

Chuchen, D. 49

Cohen, A. 143, 145, 146, 150

Cohen,'H. 118. 119, 120, 196

Cohen, S. 168

Croltoru, N. 89

Ellas, E. 23, 136

Eliezer, D. 83

Eliezer, S. 8, 41, 42, 44, 49

Elkind, M. M. 157

Engler, G. 190

Erez, G. 49

Evans, M. J. B. 98

Even, 0. 105, 177

Faber Jr., J. 69

Faraggi, M. 120, 121, 122, 123, 124

Feldstein, H. 94, 105

Ferradlni, C. 124

Frenkel, R. 204

Frledland, L. 42, 43

Friedman, M. 4, 5, 200

Freud, A. 144, 145, 148, 149

Dadon, D. 79

Daghighian, F. 43

Dariel, M. 45

Dariel, M. S. 85

Dayan, D. 80, 106

Deakyne, C. A. 125

Dikman, A. 167, 168

Dorfman, L. M. 120

Edelstein, D. 85

Eger, D. 34, 106

Eisen, Y. 199

Eldan, M. 193

Eldor, A. 153

El-Hanany, U. 72, 98

Gabay, S. 168

Gabovitz, A. 206

Gafni, G. 91, 93

Gainor, E. 183

Gal, D. 23, 26

Gal, G. 201

Ganor, M. 87

Gants, E. 180

Gardes-Albert, M. 124

Gazit, Y. 44, 49

Gefen, Y. 77, 79, 84, 87, 99, 101

Gelbart, W. M. 12

German, U. 112, 175, 176, 191

Gershuni, S. 118

Gertner, I. 77

Geyer, I. 14

254

Gilath, I. 44, 45

Giler, S. 167

Gilligan, J. 37

Givon, M. 44, 49

Glatt, I. 194, 195, 196

Gleiser, H. 85

Golan, J. 130

Goldbart, Z. 73, 105, 135, 138,

192, 193

Goldstein, M. 15

Gorin, B. S. 12

Green, M. 152, 153

Greenberg, R. 205

Greenspan, E. 19, 30, 32, 33, 34

35, 36, 37

Guiser, R. 135

Guo, Z. 27

Gur, M. 90

Gur, Y. 55

Hagag, Y. 146, 150

Halavee, U. 51, 57

Harel, A. 193

Harmin, D. A. 70

Harth, R. 133

Haruvy, Y. 127, 128

Hayrapetian, A. 43

Heller, D. F. 194, 195

Helman, C. 164

Henzel, V. 28

Herrmann, B. 85, 87

Hevron, E. 190

Hltterman, R. 69

Houee-Levin, G. 124

Horowitz, A. 117

laina, A. 166

Inspektor, A. 43, 96, 97, 98

Israeli, M. 174, 177

Issachar, D. 161, 163, 164

Ivri, J. 70, 71

Itzack, D. 84

Izak, E. 199

Jackel, S. 41, 44, 49

Jagur-Grodzinski, J. 127

Jasien, P. G. 127

Jubran, N. 120

Jung, J. 37

Juszynski, M. 130

Kafri, 0. 194, 195, 196

Kagan, J. 49, 50, 167

Kahane, S. Ill, 112, 113

Kaimal, J. C. 183

Kalisky, Y. 49, 117

Kamin, S. 201

Kaplan, I. 167

Kami, Y. 33

Karpas, Z. 125, 126, 127, 131

Katamian, D. 82

Kaufman, Y. 203, 205

Kedem, D. 199

Keidar, Y. 135

Keren, E. 194, 195

Keren, Y. 177

Ketter, A. 136

Khait, Y. L. 43, 97

Kimrael, G. 80, 106, 114

Kinrot, A. 34, 35, 36, 37

255

)

Kishlnevski, M. 4A

Klapisch, M. 14, Al

Klapper, M. H. 120, 121, 122,

123, 124

Klimker, H. 99

Kneis, H. A. 82

Koch, J. 179

Kohn, G. 81, 82

Kol, R. 156

Koresh, J. E. 98, 129

Kornblit, L. 45

Kouri, D. J. 8

Krasinski, J. 194

Kridiotis, A. C. 138

Krumbein, A. D. 41, 44

Kurizki, G. 13

Kushilevski, A. 168

Kushnir, M. 203

Kuznietz, M. 63, 64, 65, 66, 67

Lachlsh, U. 72, 98

Laichter, Y. 168, 175, 176

Lalluz, R. 49

Landau, A. 106

Laor, U. 90, 105, 199

Lapid, J. 135

Last, I. 56, 57, 58

Lavi, N. 139

Lavi, S. 49

Leibovitz, 0. 85

Lempert, G. 189

Levin, L. A. 49, 50, 167

Levin, P. 35

Levy, E. 135

Lias, S. G. 126, 131

Liebman, J. F. 131

Lifshitz, Y. 103

Linn, G. 33

Linquist, K. 157

Liran, Y. 49

Liu, J.-Y. 70

Livnat, A. 194, 195, 196

Livne, Z. 77

Loeb, A. 8, 41, 42, A3, 44

Loebenstein, H. M. 51

Longwell, J. P. 12, 138, 192

Lorber, A. 135, 138, 192, 193,

201, 202

Lotem, H. 49, 50, 167, 199

Lubensky, T. C. 6

Ludmirsky, A. 41, 44, 49

McMullen, W. E. 12

McNicholl, P. 70

Malchi, S. 174

Mantel, M. 139

Margaliot, M. 177

Mark-Markowitch, M. 205

Marko, R. 156

Marouani, D. 85

Marshall, E. W. 6

Mathias, H. 81

Matmor, A. 197

Matsumoto, K. 203

Mattenberger, K. 67

Melamud, M. 63, 68, 69

Meot-Ner, M. (Mautner) 125, 131

Meroz, E. 41

Metcalf, J. 70, 71

Metz, R. 126

256

Mey-Marom, A. 129

Meyerstein, D. 118, 119, 120

Miley, G. H. 37

Minsberg, M. 152

Miron, E. 201

Mlsulovin, A. 29

Mitra, A. 131, 132

Mor, U. 133

Moreh, R. Ill, 113, 114

Munitz, A. 77

Nairn, E. 179

Ifevo, Z. 144

Ohaion, H. 182

Oreg, J. 13, 14

Oren, Y. 133, 134, 135

Oudiz, G. 198, 201

Paiss, Y. 45

Pasi, M. 197, 198

Peled, D. 202

Pelleg, J. 80, 87, 106

Piestun, S. 198

Pinto, H. 63, 68, 69

Platzner, I. 138

Post, D. 196

Prager, A. 152, 153

Pri-Bar, I. 146, 147

Quezel, S. 65

Rabani, J. 118, 119

Rabinovitch, A. 4, 5

Rabinovitz, E. 85, 87, 96

Rahman, H. U. 72

Raizman, A. 94, 103

Rajbenbach, L. A. 127, 128

Ram, V. 81, 82

Raveh, A. 80, 85, 87, 96, 97

Raymond, A. 135

Rebizant, J. 65

Riesz, P. 123, 156

Riklis, E. 151, 152, 153, 156

Ringler, G. 159, 160

Rintler, D. 169

Ron, S. 9, 11, 38

Ronen, Y. 28

Rosenfeld, Y. 3, 12

Rosenthal, I. 155, 156

Rosenthal, Y. 205

Rossat-Mignod, J. 64, 65, 66, 67

Rostoker, N. 43, 72

Rotem, H. 173

Roth, M. 91, 93

Rotter, S. 63, 71, 72, 98

Rudensky, B. 130

Ruppin, R. 13

Sagie, D. 49, 50, 167, 168

Salzmann, D. 41, 45

Saphier, D. 19, 21, 23, 24,

26, 27

Sariel, J. 106

Sarofim, A. F. 12, 131, 132, 138, 192

Sberlo, E. 179

257

Schlesinger, T. 161, 174, 177

Schneider, A. 29

Sembira, A. N. 89

Shahal, 0. 113, 114, 197

Shaham, H. 103

Shai, I. 201

Shaked, H. 63, 68, 69

Shaked, I. 149

Shamai, Y. 174, 177

Shamash, S. 103

Shamir, N. 100

Shani, G. 112, 191

Shavit, E. 193

Shayer, Z. 30, 32

Sher, A. 94

Shima, Y. 8, 9

Shimoni, M. 143, 145, 146, 150

Shimony, Y. 90, 91, 105

Shkolnik, S. 129

Shrem, S. 159, 160

Sinvani, M. 104

Skibin, D. 182, 183

Slama-Schwok, A. 118, 119

Soffer, A. 129, 133, 134, 135

Sorek, Y. 119

Sod-Moriah, U. A. 148, 149

Spirlet, J. C. 65

Spjut, R. E. 12, 192

Steiner, J. 120, 121

Stern, A. 82

Stevens, W. J. 126

Strauss, M. 13, 43, 72

Striem, H. L. 184, 186

Sukoriansky, S. 33

Suss, J. T. 63

Szabo, J. 19

Szichman, H. 41, 44

Tadmor, J. 179, 180

Talmor, A. 168

Tamir, M. 51, 57

Teitelbaum, Z. 144, 145, 150

Thieberger, R. 5

Tobias, U. 196

Trumper, J. 158, 161, 163, 164

Tsory, E. 81

Tur, M. 51, 52

Vainas, B. 90

Vlodavsky, I. 153

Vogt, 0. 64, 65, 66, 67

Wacholder, E. 136

Waichman, K. 49

Walling, J. C. 195

Warner, D. D. 112

Watts, R. J. 119

Weatherly, G. C. 82

Weill, S. 144

Weininger, J. 158, 161, 163, 166

Weiser, G. 175, 176

Weissman, Y. 55, 56

Wietzman, Y. 97

Williams, D. J. 117

Wilson, B. 166

Wold, A. 91

Wolf, A. Ill, 112

258

Yahalom, J. 100

Yatom, H. 13

Yeheskel, 0. 79, 101

Yellin, E. 199

Yellin, N. 106

Yona, S. 176

Zafran, M. 144, 150

Zauber, H. 159, 160

Zemel, A. 63, 94

Zentner, A. 49

Zevin, L. 80, 106

Zevin, V. 63

Zigler, A. 41, 44, 49

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