A novel emulator for fission event generators

TL;DR

This paper introduces a novel emulator for the fission event generator CGMF, capable of modeling prompt neutron and gamma-ray emissions, including correlations, which enhances the simulation of fission observables.

Contribution

The work presents the first emulator for a fission event generator, combining a noisy emission model with a mixture density network to accurately simulate fission fragment emissions.

Findings

Successfully modeled average prompt fission observables.

Captured correlations between initial conditions and emissions.

Effective for both neutron-induced and spontaneous fission.

Abstract

A wide variety of emulators have been developed for nuclear physics, particularly for use in quantifying and propagating parametric uncertainties to observables. Most of these methods have been used to emulate structure observables, such as energies, masses, or separation energies, or reaction observables, such as cross sections. Rarely, if ever, have event generators for theory models been emulated. Here, we describe one such novel emulator for the fission fragment decay code, $\texttt{CGMF}$, which calculates the emission of prompt neutrons and $\gamma$ rays from fission fragments. The emulator described in this work uses a combination of a noisy emission model and mixture density network to model the neutron and $\gamma$-ray multiplicities and energies. In this manuscript, we display the power of this type of emulator for not only modeling average prompt fission observables but also correlations between fission fragment initial conditions and these observables, using both neutron-induced and spontaneous fission reactions.