On the isotopic composition of fission fragments

Abstract

We use a newly developed method, based on the original Brownian shape motion (BSM) model, to calculate fission-fragment isotopic yields Y(Z,N). Recent measurements of post-neutron isotopic distributions with better than 1 u resolution make it possible, for the first time, to test in detail this model. We here report on the comparison between the measured and the calculated fission-fragment average neutron number <N> as a function of proton number, as well as isotopic distributions for selected proton numbers. The calculated primary yields are corrected for post-scission neutron evaporation by the fragments. The highly variable dependence of <N> with Z seen in the measurements is also present in the calculations.