cross-sections of neutron threshold reactions studied by activation method

Cross-sections of Neutron Threshold Reactions studied

by activation method

Diploma ThesisVrzalová Jitka

Supervisor: RNDr. Vladimír Wagner, CSc.

Nuclear Physics Institute, Academy of Sciences of Czech RepublicDepartment of Nuclear Reactors, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague

2

Outline- Motivation

- Cross - section measurements

- Neutron sources

-Experiments-Řež

- Experiments- Uppsala

- Comparison Řež, Uppsala

- Conclusion

Motivation Nuclear data libraries Stochastic and deterministic codes Neutron sources Cross-section measurements Experiments on Cyclotron in Řež TSL Uppsala experiments Comparison Conclusion

3

Motivation for testing of the programs simulating ADS, it is

necessary to determine neutron fields

the neutron fields can be determined using the activation detectors

for neutron detection are used threshold reactions on Au, Al, Bi, In, Ta, Ni, Zn, Y, I

almost no experimental cross-section data for most of observed threshold reactions are available for higher neutron energies (E>20MeV)→it is necessary to perform new cross-section measurements

- Motivation• Introduction• Libraries• Stochastic and deterministic codes• Detection of neutrons• Evaluation


- Neutron sources

-Experiments-Řež



- Conclusion

4

Evaluated nuclear data libraries x EXFOR

nuclear data are summarized in the libraries of nuclear data and gradually updated

data form ENDF-6

general libraries (BROND-russian, CENDL-chinese, ENDF-american, JEFF- european, JENDL-japanese)

specialized libraries (MENDL, WIND, LA 100, LA 150, NRG-2003)

cross-sections are for the major part of measured isotopes published up to (n,4n) reaction (100 MeV) in ENDF, in EXFOR up to 40 MeV



- Neutron sources

-Experiments-Řež



- Conclusion

5

Stochastic codesMCNP a MCNPX MCNP simulates transport of neutrons (photons and

electrons) in energy range from 10-11 MeV to 20 MeV

MCNPX-connects and improves possibilities of MCNP, which is intended for lower energies and code LAHET, which is advisable for simulation of spallation reaction

LAHET simulates spallation reaction and transport nucleons,

pions, muons with energy E≥20 MeV

More Monte Carlo-based codes: FLUKA, HETC, NUCLEUS, SHIELD, NMTC, GEM, JAM



- Neutron sources

-Experiments-Řež



- Conclusion

6

Deterministic codesTALYS 1.0 deterministic code

provides complete calculation of the nuclear reactions in the energy range from 1 keV to 200 MeV

with TALYS code can be obtained the complete

overview of cross-sections

the output file contains all usually demanded information, more than 200 keywords could be used in the input file

More codes: GNASH, ALICE, STAPRE, EMPIRE, MEND



- Neutron sources

-Experiments-Řež



- Conclusion

7

TALYS 1.0 – nuclear models



- Neutron sources

-Experiments-Řež



- Conclusion

Bi-207

0

0,2

0,4

0,6

0,8

1

1,2

1,4

1,6

1,8

2

15 20 25 30 35 40

E [MeV]

XS

[ba

rn]

ld1 ld2 ld3 ld4 ld5 EXFOR MENDL-2

8

TALYS 1.0 – nuclear models- Motivation• Introduction• Libraries• Stochastic and deterministic codes• Detection of neutrons• Evaluation


- Neutron sources

-Experiments-Řež



- Conclusion

Bi-207

-60

-40

-20

0

20

40

60

80

15 20 25 30 35

E [MeV]

odch

ylka

[%

]ld2 ld3 ld4 ld5

Difference between cross-sections models with different nuclear level density and default Fermi model, reaction 209Bi(n,3n)207Bi

9

Detection of neutrons



- Neutron sources

-Experiments-Řež



- Conclusion

Al Au Bi Co In Ta

ReactionE thresh [MeV]

Half-life

197Au (n,2n) 196Au 8.1 6.183 d197Au (n,3n) 195Au 14.8 186.1 d197Au (n,4n) 194Au 23.2 38.02 h

209Bi (n,3n) 207Bi 14.42 31.56 y209Bi (n,4n) 206Bi 22.55 6.243 d

115In (n,2n) 114In 9.12 1.2 min

10

Evaluation- Motivation• Introduction• Libraries• Stochastic and deterministic codes• Detection of neutrons• Evaluation


- Neutron sources

-Experiments-Řež



- Conclusion

)()(

)(

11

1

)(

0

irrreal tirr

t

t

foillive

real

areaP

irrabspyield e

t

e

e

mt

t

CCoiEI

CCSN

• decay during cooling, irradiation

• unstable irradiation

• coincidences

• non point-like emitters

• detector dead time

• detector efficiency

• self-absorption

11

Cross-section measurements



- Neutron sources

-Experiments-Řež



- Conclusion

Requirements for -measurements by activation method:

high energy neutron source with good intensity

monoenergetic (quasi-monoenergetic) neutrons or well known spectrum

pure monoisotopic samples

good spectroscopic equipment – and X-rays detectors

Then we can calculate Nyield and finally :An

yield

NN

ASN

Evaluation process:

Irradiation→HPGe→Deimos→Corrections→Yield→Cross-section

Number of neutrons in peak

12



- Neutron sources

-Experiments-Řež



- Conclusion

Neutron sources source with wide spectrum of neutrons-time of flight method-determination energy of neutrons (system n_TOF in CERN), unsuitable for activation foils

quasi-monoenergetic neutron source - target + accelerator of particles - high-frequency source 7Li(p,n)7Be, 2H(d,n)3He

source CYRIC with energy range from 40 to 90 MeV in „Cyclotron and Radioisotope Center“ in Tohok

new source SPIRAL-2 is under construction in laboratory GANIL in Caen (France) (energy range to 40 MeV, high intensity)

13



- Neutron sources

-Experiments-Řež



- Conclusion

Neutron sources

Neutron source on cyclotron U-120M

Blue Hall, UppsalaQuasi-monoenergetic neutron source

14



- Neutron sources

-Experiments-Řež



- Conclusion

Experiments in Řež April, May 2009,

irradiation of the foils on cyclotron U-120M

quasi-monoenergetic neutron source based on reaction 7Li(p,n)7Be, energy range of this neutron source is 10-37 MeV

proton beam energies 32.5 and 37 MeV

irradiation time about 20 h.,irradiated foils: Ni, Zn, Bi, Cu, In, Al, Au, Ta, Fe and I

15



- Neutron sources

-Experiments-Řež



- Conclusion

Experiments in Řež

16



- Neutron sources

-Experiments-Řež



- Conclusion

Experiments in Uppsala February 2010, June

2008

quasi-monoenergetic neutron source based on reaction 7Li(p,n)7Be, energy range of this neutron source is 11-175 MeV

proton beam energies 25, 50, 100 MeV (June 2008); 62, 70, 80, and 93 MeV (February 2010)

irradiation time about 8 h.,irradiated foils: Au, Bi, In, Al, Ta, Co, Y and I

17



- Neutron sources -Experiments-Řež



- Conclusion

Experiments in Uppsala

samples for irradiation

HPGe detector

placing samples toward detector

18



- Neutron sources

-Experiments-Řež



- Conclusion

Comparison Řež, Uppsala

Řež

Uppsala

Au-196

0

0,5

1

1,5

2

2,5

3

0 10 20 30 40 50 60 70 80 90E [MeV]

XS

[ba

rn]

EXFOR TALYS ÚJF Řež TSL Uppsala

Comparison of cross-section reaction (n,2n) 197Au with EXFOR and TALYS

Řež

Uppsala

19



- Neutron sources

-Experiments-Řež



- Conclusion


Řež

Uppsala

Uppsala

In-114m

0

0,3

0,6

0,9

1,2

1,5

1,8

8 18 28 38 48 58 68 78 88 98

E [MeV]

XS

[ba

rn]

EXFOR TALYS ÚJF Řež TSL Uppsala

Comparison of cross-section reaction (n,xn) natIn with EXFOR and TALYS

Řež

Uppsala

20



- Neutron sources

-Experiments-Řež



- Conclusion


Řež

Uppsala

Uppsala

Comparison of cross-section reaction (n,2n) 64Zn with EXFOR and TALYS

Zn-63

0

0,05

0,1

0,15

0,2

0,25

0,3

0,35

0,4

0,45

0,5

12 17 22 27 32 37

E [MeV]

XS

[b

arn

]TALYS ÚJF Řež EXFOR, Y. Uwamino, 1992 EXFOR, A.A.Lapenas, 1975

Řež

21



- Neutron sources

-Experiments-Řež



- Conclusion

Conclusion Our cross-section measurements in Uppsala and Řež

cover wide spectrum of energies

Our results for well known cross-sections agree with

other experimental data

We measured also a lot of new experimental data

Near future: publish the measured cross-sections from

Uppsala at February 2010

Thanks for attention

cross-sections of neutron threshold reactions studied by activation method

Documents

e experiments

uppsala comparison e

libraries of nuclear

nuclear reactions

faculty of nuclear sciences

input filemore codes

transport of neutrons

nuclear physics institute