ddep-2008 workshop, 2008, may 12-14, bucharest, romania 1 evaluation of 236 u nuclear decay data...

DDEP-2008 Workshop, 2008, May 12-14, Bucharest, Romania

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EVALUATION OF 236U NUCLEAR DECAY DATA

Aurelian Luca “Horia Hulubei” National Institute of Physics and

Nuclear Engineering (IFIN-HH), Radioisotope Production Dept., Radionuclide Metrology

Laboratory, Magurele, Romania


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Introduction

• The evaluation of 236U nuclear decay data was performed in the frame of the IAEA Research contract no. 13341/2005 (“Improved decay data for important actinides”), within the IAEA CRP “Updated Decay Data Library for Actinides”, according to the DDEP procedures.

• 236U: alpha-gamma radiations emitter, with weak spontaneous fission (9.410-8 % branch) and very weak cluster decay – Ne and Mg emission (~10-13 probability relative to alpha decay, according to Tretyakova et al., 1994).


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References (selection)• K.F. Flynn, A.H. Jaffey, W.C. Bentley and A.M. Essling, “Precision

Measurement of Half-Life and Specific Activity of 236U”, J. Inorg. Nucl. Chem. 34, 1121-1129, 1972

• A. Rytz, “New Catalogue of Recommended Alpha Energy and Intensity Values”, At. Data Nucl. Data Tables 23, 507-533, 1979.

• W.B. Ewbank, Y.A. Ellis and M.R. Schmorak, “Spontaneous Fission Activities”, Nuclear Data Sheets 26, 1-3, 1979.

• M.R. Schmorak, “Nuclear Data Sheets for A=232, 236”, Nuclear Data Sheets 36, 367-427, 1982 and Nuclear Data Sheets 63, 139-215, 1991

• S.N. Belenky, M.D. Skorokhvatov and A.V. Etenko, “Measurement of the Characteristics of Spontaneous Fission of 238U and 236U”, Sov. At. Energy 55, 528-531, 1983.

• “Decay Data of the Transactinium Nuclides”, Technical Reports Series no. 261, IAEA, Vienna, 1986, A. Lorenz, p. 157,163, 168.

• R.J. Gehrke, J.D. Baker and C.L. Riddle, “Feeding of the 232Th levels from the decay of 236U”, Appl. Radiat. Isot. 56, 567-568, 2002.

• G. Audi, A.H. Wapstra and C. Thibault, "The Ame2003 atomic mass evaluation (II)", Nuclear Physics A729, 337-676, 2003.

• E. Browne, “Nuclear Data Sheets for A=232”, Nuclear Data Sheets 107, 2579, 2006


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236U Nuclear Decay Scheme (Isotope Explorer v.2.23/1999)


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Evaluation Tools (software)

• SAISINUC 2000, version 2006-fevrier, 2/16/2006 [Laboratoire National “Henri Becquerel”(LNHB), CEA, BNM, France]

• Lweight4 for Excel (C. Dulieu, LNHB), based on LWeight (D. MacMahon, E. Browne)

• ICC2005 (LNHB, CEA, BNM, France)• BrIcc v.2.0 (T. Kibedi et al., 2005)• EMISSION v.3.03, 2001 (PTB, Germany)• Nuclear Science References (NSR) database,

NNDC/BNL, USA (http://www.nndc.bnl.gov/nsr/)

http://www.nndc.bnl.gov/nsr/


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Half-life Evaluation

Crt. No.

Half-life and uncertainty

(/107 years)

Reference Evaluated value

(/107 years)

1. 2.46(14) Jaffey et al., 1951

2. 2.391(57) Fleming et al., 1952 2.371(37)

3. 2.3415(39) Flynn et al., 1972


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Spontaneous Fission Half-life Evaluation

Crt.No.

S.F. Half-life & uncertainty

(/1016 years)

Reference Evaluated value

(/1016 years)

1. 2.0(16) Jaffey and Hirsch (1949)

2. 2.7(3) Conde and Holmberg (1971)

2.56(17)

3. 2.43(13) von Gunten et al. (1981)

4. 2.7(4) Belenky et al. (1983)


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Alpha Emissions, Normalization, Other Details

• The spin, parity and energy levels, alpha and gamma-ray transitions energies, alpha intensities, are adopted from the recent evaluation of E. Browne (2006); the relative -ray emission intensities are from the measured values of Gehrke et al., 2002.

• The alpha energy, intensity and their uncertainty values are: 4168 keV [0.000 001 42 (48)], 4332 (8) keV [0.001 49 (22)], 4445 (5) keV [0.261 (40)]; the resulting intensity of the main emission [4494 (3) keV] is 0.738 (40).

• Normalization for the 232Th ground state:

%081.04.3241

)%8.73100()(

%100)()1()()()(

10

10100100

I

IIceII


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Gamma-ray Emission Intensities

Energy / keV Emission intensity and uncertainty Data Uncertainty Relative / % Absolute (gammas/decay) 49.46 0.10 100 0.000 81 0.000 12

112.79 0.10 24.1 0.1 0.000 195 0.000 032 171.15 0.20 0.080 0.024 0.000 000 65 0.000 000 22


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Internal Conversion Coefficients (ICC)

• The most important case: 49.46 keV gamma-ray transitionsShell Internal

conversion coefficient

BrIcc

Internal conversion coefficient ICC2005

(with hole hypothesis, WH)


(without hole hypothesis, W/H)

Total 3.244102 3.244102 3.240102 K - - - L1 3.989100 3.989100 3.977100

L2 1.242102 1.242102 1.239102

L3 1.093102 1.093102 1.093102

L-total 2.375102 2.375102 2.372102

M-total 6.499101 6.499101 6.494101

N-total 1.739101 1.739101 1.738101

O-total 3.865100 3.865100 3.864100

P-total 6.37110-1 6.37210-1 6.37210-1

Q-total 1.70510-3 1.70610-3 1.70610-3


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Internal Conversion Coefficients (ICC) cont.

• The weak conversion case: 171.15 keV gamma-ray transitionsShell Internal

conversion coefficient

BrIcc


(with hole hypothesis, WH)


(without hole hypothesis, W/H)

Total 1.187100 1.186100 1.180100 K 2.04310-1 2.04310-1 1.98810-1 L1 4.91310-2 4.91410-2 4.87710-2

L2 4.31210-1 4.31210-1 4.30710-1

L3 2.38710-1 2.38710-1 2.38610-1

L-total 7.19010-1 7.19010-1 7.18110-1

M-total 1.96710-1 1.96710-1 1.96610-1

N-total 5.27110-2 5.27110-2 5.27010-2

O-total 1.18010-2 1.18010-2 1.18010-2

P-total 1.98210-3 1.98210-3 1.98210-3

Q-total 1.85510-5 1.85510-5 1.85510-5


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X-rays Energy and Intensity ValuesTable of Isotopes,

http://isotopes.lbl.gov/education/ Present evaluation X-rays

assignment E / keV

Intensity and Uncertainty Intensity and Uncertainty

Th Ll 11.118 0.00202(20) 0.00194(26) Th L 12.809 and

12.968 0.0345(18) 0.032(4)

Th L 14.511 0.00096(10) 0.00108(17) Th L 14.97,

15.605, 15.641, 16.202, 16.209, 16.426

0.048(4) 0.047(6)

Th L 18.98, 19.304, 19.505, 19.599

0.0106(9) 0.0111(14)

Th L total From 11.118 to

19.599

0.096(4) 0.094(10)

Th K3 89.178 3.6(4) 10-8 - Th K2 89.954 1.20(13) 10-5 1.28(22) 10-5

Th K1 93.351 1.96(21) 10-5 2.1(4) 10-5 Th K3 + Th K1 + Th K5

104.819 + 105.604 + 106.239

7.2(6) 10-6 7.4(13)10-6

Th K2 + Th K4 + Th KO2,3

108.509 + 108.955 + 109.442

2.35(20) 10-6 2.5(5)10-6


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CONCLUSIONS

• The evaluation of 236U nuclear decay data was performed in the frame of the IAEA Research Project no.13341/2005, according to the DDEP procedures and by using several evaluation tools.

• The normalization condition applied to the 232Th ground state, lead to the absolute intensity value of the main gamma-ray emission of 49.46 keV.

• An excellent agreement was obtained in computing the ICC values with the BrIcc v.2.0a and ICC2005 (with hole hypothesis) software.

• The X-rays intensity values are in good agreement with the values from TOI, but have higher uncertainties; a future comparison with experimental values would be very useful.


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Acknowledgements

Thanks are due to:

• IAEA and Dr. Mark A. Kellett (Project Officer)

• Dr. Marie-Martine Be

• Dr. Valery P. Chechev

• Dr. Filip G. Kondev

• Dr. Edgardo Browne

• U.S. Department of Energy (for using Isotope Explorer)


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THANK YOU !

ddep-2008 workshop, 2008, may 12-14, bucharest, romania 1 evaluation of 236 u nuclear decay data...

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