Heavy deformed nuclei in the shell model Monte Carlo method

TL;DR

This paper extends the shell model Monte Carlo method to heavy deformed nuclei, successfully reproducing rotational behavior and accurately predicting level densities for 162Dy, a well-deformed rare-earth nucleus.

Contribution

The authors develop a proton-neutron formalism and stabilization technique for low-temperature calculations in the shell model Monte Carlo approach applied to heavy deformed nuclei.

Findings

Reproduces the rotational character of 162Dy

Accurately predicts the level density of 162Dy

Demonstrates the effectiveness of the extended method for heavy nuclei

Abstract

We extend the shell model Monte Carlo approach to heavy deformed nuclei using a new proton-neutron formalism. The low excitation energies of such nuclei necessitate calculations at low temperatures for which a stabilization method is implemented in the canonical ensemble. We apply the method to study a well deformed rare-earth nucleus, 162Dy. The single-particle model space includes the 50-82 shell plus 1f_{7/2} orbital for protons and the 82-126 shell plus 0h_{11/2}, 1g_{9/2} orbitals for neutrons. We show that the spherical shell model reproduces well the rotational character of 162Dy within this model space. We also calculate the level density of 162Dy and find it to be in excellent agreement with the experimental level density, which we extract from several experiments.