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EVALUATION OF 236 U NUCLEAR DECAY DATA

EVALUATION OF 236 U NUCLEAR DECAY DATA. Aurelian Luca “Horia Hulubei” National Institute of Physics and Nuclear Engineering (IFIN-HH), Radioisotope Production Dept., Radionuclide Metrology Laboratory, Magurele, Romania. Introduction.

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EVALUATION OF 236 U NUCLEAR DECAY DATA

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

  2. 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 (9.410-8 % branch) and very weak cluster decay – Ne and Mg emission (~10-13 probability relative to alpha decay, according to Tretyakova et al., 1994). DDEP-2008 Workshop, 2008, May 12-14, Bucharest, Romania

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

  4. 236U Nuclear Decay Scheme (Isotope Explorer v.2.23/1999) DDEP-2008 Workshop, 2008, May 12-14, Bucharest, Romania

  5. 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/) DDEP-2008 Workshop, 2008, May 12-14, Bucharest, Romania

  6. Half-life Evaluation DDEP-2008 Workshop, 2008, May 12-14, Bucharest, Romania

  7. Spontaneous Fission Half-life Evaluation DDEP-2008 Workshop, 2008, May 12-14, Bucharest, Romania

  8. 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: DDEP-2008 Workshop, 2008, May 12-14, Bucharest, Romania

  9. Gamma-ray Emission Intensities DDEP-2008 Workshop, 2008, May 12-14, Bucharest, Romania

  10. Internal Conversion Coefficients (ICC) • The most important case: 49.46 keV gamma-ray transitions DDEP-2008 Workshop, 2008, May 12-14, Bucharest, Romania

  11. Internal Conversion Coefficients (ICC) cont. • The weak conversion case: 171.15 keV gamma-ray transitions DDEP-2008 Workshop, 2008, May 12-14, Bucharest, Romania

  12. X-rays Energy and Intensity Values DDEP-2008 Workshop, 2008, May 12-14, Bucharest, Romania

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

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

  15. THANK YOU! DDEP-2008 Workshop, 2008, May 12-14, Bucharest, Romania

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