Collective enhancement in the exciton model

TL;DR

This paper investigates a collective enhancement modification to the exciton model's state density, demonstrating its effects on neutron spectra and nuclear reaction calculations, especially for deformed actinides like 239-Pu.

Contribution

It introduces a collective enhancement to the exciton model's state density and explores its implications for nuclear reaction simulations and removal of fictitious levels.

Findings

Enhanced neutron-leakage spectra fit experimental data better.

Removal of fictitious levels in reaction calculations.

Significant impact on modeling highly deformed nuclei.

Abstract

The pre-equilibrium reaction mechanism is considered in the context of the exciton model. A modification to the one-particle one-hole state density is studied which can be interpreted as a collective enhancement. The magnitude of the collective enhancement is set by simulating the Lawrence Livermore National Laboratory (LLNL) pulsed-spheres neutron-leakage spectra. The impact of the collective enhancement is explored in the context of the highly deformed actinide, 239-Pu. A consequence of this enhancement is the removal of fictitious levels in the Distorted-Wave Born Approximation often used in modern nuclear reaction codes.