The CSM extension for the description of positive and negative parity bands in even-odd nuclei

TL;DR

This paper extends the particle-core Hamiltonian model to describe positive and negative parity bands in odd-mass nuclei $^{237}$U and $^{239}$Pu, comparing calculations with experimental data and exploring signs of octupole deformation.

Contribution

The study introduces a unified particle-core Hamiltonian approach for odd-mass nuclei, incorporating quadrupole and octupole interactions, and applies it to specific isotopes to analyze parity partner bands.

Findings

Calculated energies agree with experimental data

Identified signatures of static octupole deformation

Extended the model to odd-mass nuclei with complex interactions

Abstract

A particle-core Hamiltonian is used to describe the lowest parity partner bands $K^{\pi}=1/2^{\pm}$ in $^{237}$U and $^{239}$Pu. The quadrupole and octupole boson Hamiltonian associated to the core is identical to the one previously used for the description of four positive and four negative parity bands in the neighboring even-even isotopes. The single particle space for the odd nucleon consists of three spherical shell model states, two of positive and one of negative parity. The particle-core Hamiltonian consists of four terms: a quadrupole-quadrupole, an octupole-octupole, a spin-spin and a rotational $\hat{I}^2$ interaction, with $\hat {I}$ denoting the total angular momentum. The parameters involved in the particle-core coupling Hamiltonian were fixed by fitting four particular energies in the two bands. The calculated excitation energies are compared with the corresponding experimental data as well as with those obtained with other approaches. Also, we searched for some signatures for a static octupole deformation in the considered odd isotopes.