Using CGMF to estimate corrections for fission yields measured via γ-ray spectroscopy

¹ System Evaluation Division, Institute for Defense Analyses, Alexandria, VA 22311, USA
² Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
³ XCP-5, Computational Physics Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
⁴ Physics Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA

^* e-mail: pjaffke@ida.org

Published online: 28 September 2020

Abstract

Fission product yields have been inferred using γ-ray spectroscopy for several decades. Typically, these efforts have focused on even-Z even-A fission products as their nuclear structure are less complicated. To further simplify the situation, it is often assumed that no side-feeding to the ground-state occurs and multiplicity cuts have a negligible effect on the inferred yields. Using CGMF, a Hauser-Feshbach statistical decay model for the primary fission fragments, we estimate the impact of these assumptions and determine corrections for specific fission product yields. We report on these corrections and investigate their sensitivity to various nuclear parameters, specifically the spin distribution of the fission fragments and the assumed nuclear structure. Our results indicate that even in the simplest of cases, say the 2⁺ → 0⁺ transitions in even-Z even-A fragments, average level corrections are on the order of 75%.