Microscopic treatment of energy partition in fission

TL;DR

This paper presents a microscopic model of nuclear fission that accurately predicts neutron emission patterns by considering energy partition and shape evolution of fission fragments.

Contribution

It introduces a detailed microscopic approach to energy partition in fission, incorporating finite-size effects and statistical level densities for improved predictions.

Findings

Good agreement with observed neutron multiplicity in $^{235}$U(n,f)

Accurate modeling of energy-dependent shape evolution

Predicts fragment mass and excitation energy distribution

Abstract

The transformation of an atomic nucleus into two excited fission fragments is modeled as a strongly damped evolution of the nuclear shape, until scission occurs at a small critical neck radius, at which point the mass, charge, and shape of each fragment are extracted. The available excitation energy then is divided statistically on the basis of the microscopic level densities. This approach takes account of the important (and energy-dependent) finite-size effects. After the fragments have been fully accelerated and their shapes have relaxed to their equilibrium form, they undergo sequential neutron evaporation. The dependence of the resulting mean neutron multiplicity on the fragment mass, $\bar{\nu}$(A), including the dependence on the initial excitation energy of the fissioning compound nucleus, is in good agreement with the observed behavior, as demonstrated here for $^{235}$U(n,f).