Uncertainty quantification of optical models in fission fragment de-excitation

TL;DR

This paper investigates how uncertainties in optical models affect predictions of fission fragment de-excitation, highlighting significant impacts on neutron-fragment correlations and identifying features unexplained by current models.

Contribution

It introduces a method to propagate optical model uncertainties into fission observables using Monte Carlo Hauser-Feshbach calculations, comparing phenomenological and microscopic potentials.

Findings

Parametric optical model uncertainty significantly affects neutron-fragment correlations.

Certain experimental features near shell closures are not explained by optical potential variations.

Some neutron spectra features require further experimental and theoretical investigation.

Abstract

We take the first step towards incorporating compound nuclear observables at astrophysically relevant energies into the experimental evidence used to constrain optical models, by propagating the uncertainty in two global optical potentials, one phenomenological and one microscopic, to correlated fission observables using the Monte Carlo Hauser-Feshbach formalism. We compare to a wide range of historic and recent experimental fission measurements, and discuss in detail regions of disagreement. We find that the parametric optical model uncertainty in neutron-fragment correlated observables involving neutron energy is significant. On the other hand, we observe that other experimental features, particularly neutron-fragment correlations near the $^{132}$Sn shell-closure and the high energy component of neutron spectra, are unlikely to be explained by the optical potential, and will require further experimental and theoretical effort to explain.