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Evaluations of Photonuclear Cross Sections for Actinides

Marie-Laure Giacri-Mauborgne for PAF collaboration CEA Saclay, DSM/DAPNIA/SPhN, 91191 Gif-sur-Yvette, France. Evaluations of Photonuclear Cross Sections for Actinides. PAF – Photonuclear Activation File. PAF. Photons E<25 MeV. 155 isotopes. Z≤84 Cross Sections. Z>84. 9 isotopes.

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Evaluations of Photonuclear Cross Sections for Actinides

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  1. Marie-Laure Giacri-Mauborgne for PAF collaboration CEA Saclay, DSM/DAPNIA/SPhN, 91191 Gif-sur-Yvette, France Evaluations of Photonuclear Cross Sections for Actinides PAF – Photonuclear Activation File

  2. PAF Photons E<25 MeV 155 isotopes Z≤84 Cross Sections Z>84 9 isotopes 6 isotopes IAEA Cross sections Fission products ABLA GNASH HMS-ALICE Frame of this work • Creation of Photonuclear Activation File (PAF) • New capability for CINDER’90 : activation analysis in photon fluxes Procedure: • IAEA Evaluations for 164 isotopes • Use HMS-ALICE to predict most of the cross sections (~500) • Use of GNASH to evaluate “important” nuclei: 235U, 238U, 237Np, 239Pu, 240Pu, 241Am others

  3. HMS-ALICE vs GNASH

  4. New photoabsorption cross sections for HMS-ALICE • Photoabsorption is now modeled with two Lorentzians instead of one • Use of RIPL2 parameters and the dipolar sum rule

  5. Predictions using HMS-ALICE • Improvement of the photonuclear reactions cross sections • Good enough for actinides of secondary importance • For important actinides use of data from IAEA or new evaluations with GNASH

  6. Use of GNASH for actinides • Need of total photoabsorption cross section as input (data or RIPL-2) • Use of the same input parameters as for neutron induced reactions, except that the (n,) reaction is suppressed • Adjustment of parameters, in particular the fission barrier, to reproduce the experimental data for separate reaction channels

  7. Test of GNASH evaluations for 235U, 238U, 239Pu • First evaluations of this type using GNASH • Satisfactory results • Validation of GNASH for actinides

  8. GNASH for 237Np • No direct measurement of photoabsorption • Experimental data disagree • GNASH: consistency between the photoabsorption and photofission cross sections • Comparison of the evaluations with integral measurement  OK

  9. GNASH for 241Am and 240Pu • No data for photoabsorption • use of RIPL-2 parameters • Inconsistency of experimental data • Comparison of the evaluations with integral measurement  OK • Use of RIPL-2 parameters for photoabsorption • No integral measurements for 240Pu • Need of experimental data

  10. Comparison with integral data • Relative fission rates for 237Np and 241Am with respect to 238U for different Bremsstrahlung energies [Ale86] YF 43 290 (1986) [Hui54] PR 95, 1009 (1954) [Vin76] YF 24 686 (1976) Reasonable agreement with data  validation of evaluations

  11. Conclusions • GNASH is well suited for photonuclear reactions: both actinides and non-actinides • Release of the Photonuclear Activation File (PAF) is planned by the end of 2005, including • Photonuclear cross sections for more than 600 isotopes • Photofission fragment yield distributions • Delayed neutron spectrum induced by photofission • Release of 6 evaluations based on GNASH within ENDF-B/VII is planned this year: 235U, 238U, 237Np, 239Pu, 240Pu, 241Am • Urgent need of experimental data, both exclusive and integral measurements for validation and further evaluations

  12. Outlook and collaboration • continue evaluations with GNASH • test TALYS for photonuclear reactions • collaboration with JEFF community PAF collaboration: D. Ridikas, M.L. Giacri-Mauborgne, J.C. David, D. Doré, A. Van Lauwe (CEA/DSM) M. Chadwick, B. Wilson, M. Blann, P. Young (LANL) K.H. Schmidt, A. Kelic (GSI) X. Ledoux, A. Binet (CEA/DIF) M. Gmar, B. Poumarede (CEA/DRT)

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