Calculation of fission product yields for some nuclei with TALYS code

M Sabri,M Haddad

doi:10.1051/epjconf/20100214003

Abstract

We have carried out a calculation of the transmission coe cients per fission mode and determined the fission product yields for some nuclei using the Talys-0.72 version of the code(1). For fission, this code uses a statistical approach based on a revised version of the multi-modal random neck-rupture model (MM-RNRM). The fragment mass distribution is the sum of the three dominant fission modes: the superlong (SL), the standard I (ST I) and the standard II (ST II). The relative contribution of each mode is deduced from the calculation of the transmission coe cients according to the Hill-Wheeler expression taking into account the relevant transition states. The shell and pairing corrections are introduced in the level density parameter according to the Ignatyuk(2) formula. The calculated transmission coe cients values per fission mode are compared with the existing values. First, we reproduced the fragment mass distributions obtained using theTalys-0.64 version of the code for the fission of 238 U induced by 1.6 and 5.5 MeV neutrons with the 'constant temperature model' of Gilbert and Cameron(3), then we extended the calculations to other actinides with other level density models(4)(5). Finally, these calculated values of fission yields are compared with the experimental data.

Highlights

The calculation of the fission products yields requires the knowledge of two determining factors: level density and transmission coefficient
We reproduced the fragment mass distributions obtained using theTalys-0.64 version of the code for the fission of 238 U induced by 1.6 and 5.5 MeV neutrons with the ’constant temperature model’ of Gilbert and Cameron[3], we extended the calculations to other actinides with other level density models[4][5]
At low excitation energy, this is given by the experiments given discrete levels, whereas at high energy, it is given by the Fermi gas model

Summary

Introduction

The calculation of the fission products yields requires the knowledge of two determining factors: level density and transmission coefficient. The level density is described in different ways with excitation energy. Calculation of the transmission coefficients and fission modes SL, STI and STII probabilities. Between the fission barriers, resonance states known as classes I or II (respectively, in the first and second well) can be built. These states increase the transmission through the barrier.

Fission fragment mass distribution

Th experimental data

Talys code

Conclusion