Extension of the Hauser-Feshbach Fission Fragment Decay Model to Multi-Chance Fission

TL;DR

This paper extends the $ exttt{HF^3D}$ fission fragment decay model to include multi-chance fission up to 20 MeV, enabling comprehensive simulation of prompt and delayed particle emissions in fissile systems.

Contribution

The work introduces multi-chance fission into the $ exttt{HF^3D}$ model, allowing for detailed decay analysis beyond first-chance fission, improving modeling accuracy for neutron-induced fission.

Findings

Successfully implemented multi-chance fission in $ exttt{HF^3D}$

Enabled calculation of prompt neutron and gamma properties beyond first chance

Demonstrated model with neutron-induced fission on $^{235}$U

Abstract

The Hauser-Feshbach fission fragment decay model, $\mathtt{HF^3D}$, which calculates the statistical decay of fission fragments, has been expanded to include multi-chance fission, up to neutron incident energies of 20 MeV. The deterministic decay takes as input pre-scission quantities - fission probabilities and the average energy causing fission - and post-scission quantities - yields in mass, charge, total kinetic energy, spin, and parity. From these fission fragment initial conditions, the full decay is followed through both prompt and delayed particle emissions, allowing for the calculation of prompt neutron and $\gamma$ properties, such as multiplicity and energy distributions, both independent and cumulative fission yields, and delayed neutron observables. In this work, we describe the implementation of multi-chance fission into the $\mathtt{HF^3D}$ model, and show an example of prompt and delayed quantities beyond first-chance fission, using the example of neutron-induced fission on $^{235}$U. This expansion represents significant progress in consistently modeling the emission of prompt and delayed particles from fissile systems.