Connecting Experimental and Modeling Uncertainties Using Fission Observables

Los Alamos National Laboratory, Los Alamos, NM, 87545, USA

^* e-mail: fdiaby@lanl.gov

Published online: 14 March 2025

Abstract

Understanding fission processes presents a challenge due to their complex nature. Our study begins with a comprehensive assessment of the uncertainty of experimental fission cross-section data for ²³⁵U using the template of expected fission cross-section measurement uncertainties to identify missing uncertainties. The code ARIADNE, developed at Los Alamos National Laboratory (LANL), is employed to quantify these experimental uncertainties. This work presents progress towards connecting pre-and post-scission fission modeling with experimental uncertainty quantification for fission cross sections. To this end, the study uses two the-oretical model codes developed at LANL: CoH for modeling ²³⁹Pu fission cross section and the fission event generator CGMF for computing prompt fission observables. The multi-chance fission probability (MCFP) derived from sampling the fission barrier parameters in CoH covering the range of experimental data is utilized as input to CGMF, and its impact on the average prompt fission neutron multiplicity (ν) is examined. The 20% spread in the multi-chance fission probabilities corresponds to a negligible spread in ν of approximately 0.5% at the second-and third-chance fission thresholds.