Nuclear Level Density of ${}^{161}$Dy in the Shell Model Monte Carlo Method

TL;DR

This paper extends the shell-model Monte Carlo method to study the level density of the odd-even nucleus ${}^{161}$Dy, overcoming computational challenges by combining level counting and resonance data, and achieves excellent agreement with experimental results.

Contribution

The paper introduces a novel approach to determine ground-state energy in odd nuclei using combined data, enabling accurate level density calculations in the shell-model Monte Carlo framework.

Findings

Level density of ${}^{161}$Dy matches experimental data closely.

The method effectively addresses the sign problem at low temperatures.

Ground-state energy is accurately extracted using combined data.

Abstract

We extend the shell-model Monte Carlo applications to the rare-earth region to include the odd-even nucleus ${}^{161}$Dy. The projection on an odd number of particles leads to a sign problem at low temperatures making it impractical to extract the ground-state energy in direct calculations. We use level counting data at low energies and neutron resonance data to extract the shell model ground-state energy to good precision. We then calculate the level density of ${}^{161}$Dy and find it in very good agreement with the level density extracted from experimental data.