Unified description of fission in fusion and spallation reactions

TL;DR

This paper develops a unified statistical model for fission in both fusion and spallation reactions, accurately predicting fission probabilities and fragment distributions across various energies and spins.

Contribution

It introduces a consistent parameter set that describes fission in different reaction types within the same framework, incorporating transient effects and barrier modifications.

Findings

Reproduces experimental fission probabilities and fragment distributions.

Uses the Liège Intranuclear Cascade Model for initial states.

Achieves accurate predictions up to 300 MeV excitation energy.

Abstract

We present a statistical-model description of fission, in the framework of compound-nucleus decay, which is found to simultaneously reproduce data from both heavy-ion-induced fusion reactions and proton-induced spallation reactions at around 1 GeV. For the spallation reactions, the initial compound-nucleus population is predicted by the Li\`{e}ge Intranuclear Cascade Model. We are able to reproduce experimental fission probabilities and fission-fragment mass distributions in both reactions types with the same parameter sets. However, no unique parameter set was obtained for the fission probability. The introduction of fission transients can be offset by an increase of the ratio of level-density parameters for the saddle-point and ground-state configurations. Changes to the finite-range fission barriers could be offset by a scaling of the Bohr-Wheeler decay width as predicted by Kramers. The parameter sets presented allow accurate prediction of fission probabilities for excitation energies up to 300 MeV and spins up to 60 \hbar.