PREDICTION OF FISSION MASS YIELD DISTRIBUTIONS BASED ON CROSS-SECTION EVALUATIONS

Abstract

The statistical model for fission cross-section evaluation is extended by the concept of multi-modality of the fission process. The three most dominant fission modes, the two asymmetric standard I (S 1) and standard I1 (S2) modes and the symmetric superlong (SL) mode are taken into account. Deconvoluted fission cross-sections for S1, S2 and SL modes for "5~238U(n, f) and 237Np(n, f), based on experimental branching ratios, were calculated for the first time in the incident neutron energy range from 0.01 to 5.5 MeV. Good agreement was found with the experimental fission cross-section data. Branching ratios were deduced for the different modes over the whole incident neutron energy region. Fission fragment mass yield distributions have been calculated at incident neutron energies, where no experimental data exist.