Measurement of relative isotopic yield distribution of even-even fission fragments from ${}^{235}$U($n_{th}$,$f$) following ${\hat{I}}^3$ ray spectroscopy

Abstract

A detailed investigation on the relative isotopic distributions has been carried out for the first time in case of even-even correlated fission fragments for the ${}^{235}$U($n_{th}$,$f$) fission reaction. High-statistics data were obtained in a prompt ${\hat{I}}^3$ ray spectroscopy measurement during the EXILL campaign at ILL, Grenoble, France. The extensive off-line analysis of the coincidence data have been carried out using four different coincidence methods. Combining the results from 2-dimensional ${\hat{I}}^3-{\hat{I}}^3$ and 3-dimensional ${\hat{I}}^3-{\hat{I}}^3-{\hat{I}}^3$ coincidence analysis, a comprehensive picture of the relative isotopic yield distributions of the even-even neutron-rich fission fragments has emerged. The experimentally observed results have been substantiated by the theoretical calculations based on a novel approach of isospin conservation, and a reasonable agreement has been obtained. The calculations following the semi-empirical GEF model have also been carried out. The results from the GEF model calculations are found to be in fair agreement with the experimental results.

Accepted in PRC; nucl-ex; nucl-th