Prediction of Fission Mass-Yield Distributions based on Cross Section Calculations

For the first time, fission mass-yield distributions have been predicted based on an extended statistical model for fission cross section calculations. In this model, the concept of the multi-modality of the fission process has been incorporated. The three most dominant fission modes, the two asymmetric standard I (S1) and standard II (S2) modes and the symmetric superlong (SL) mode are taken into account. De-convoluted fission cross sections for S1, S2 and SL modes for 235,238U(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 providing good agreement with the experimental fission cross section data. The branching ratios obtained from the modal fission cross section calculations hve been used to deduce the corresponding fission yield distributions, including mean values also for incident neutron energies hitherto not accessible to experiment.JRC.D.5-Neutron physic