Semi-empirical model to determine pre- and post-neutron fission product yields and neutron multiplicity

TL;DR

This paper presents a semi-empirical model to accurately predict post-neutron emission fission product yields from pre-neutron yields and neutron multiplicity, validated against experimental data for specific actinides.

Contribution

The paper introduces a novel semi-empirical approach to convert pre-neutron FPYs to post-neutron FPYs using neutron multiplicity, validated with experimental data.

Findings

The model accurately reproduces experimental pre- and post-neutron FPY distributions.

The approach aligns well with GEF, ENDF, and EXFOR data for key actinides.

The method provides a reliable tool for fission yield predictions.

Abstract

Post-neutron emission fission product mass distributions are calculated by using pre-neutron emission fission product yields (FPYs) and neutron multiplicity. A semi-empirical model is used to calculate the pre-neutron FPY, first. Then the neutron multiplicity for each fission fragment mass is used to convert the pre-neutron FPY to the post-neutron FPY. In doing so, assumptions are made for the probability for a pre-emission fission fragment with a mass number $A^*$ to decay to a post-emission fragment with a mass number $A$. The resulting post-neutron FPYs are compared with the data available. The systems where the experimental data of not only the pre- and post-neutron FPY but also neutron multiplicity are available are the thermal neutron-induced fission of $^{233}$U, $^{235}$U and $^{239}$Pu. Thus, we applied the model calculations to these systems and compared the calculation results with those from the GEF and the data from the ENDF and the EXFOR libraries. Both the pre- and post-neutron fission product mass distributions calculated by using the semi-empirical model and the neutron multiplicity reproduce the overall features of the experimental data.