Application of the triaxial quadrupole-octupole rotor to the ground and negative-parity levels of actinide nuclei

TL;DR

This paper models the positive- and negative-parity excitations of actinide nuclei using a triaxial quadrupole-octupole rotor approach, explaining energy displacements through nuclear triaxiality.

Contribution

It introduces a collective rotation model incorporating triaxial quadrupole and octupole deformations to describe parity bands in actinide nuclei.

Findings

Energy displacement explained by quadrupole-octupole triaxiality.

Model successfully describes yrast positive- and negative-parity bands.

Triaxial rotor approach aligns with experimental data.

Abstract

In this work we examine the possibility to describe yrast positive- and negative-parity excitations of deformed even-even nuclei through a collective rotation model in which the nuclear surface is characterized by triaxial quadrupole and octupole deformations. The nuclear moments of inertia are expressed as sums of quadrupole and octupole parts. By assuming an adiabatic separation of rotation and vibration degrees of freedom we suppose that the structure of the positive- and negative- parity bands may be determined by the triaxial-rigid-rotor motion of the nucleus. By diagonalizing the Hamiltonian in a symmetrized rotor basis with embedded parity we obtain a model description for the yrast positive- and negative-parity bands in several actinide nuclei. We show that the energy displacement between the opposite-parity sequences can be explained as the result of the quadrupole-octupole triaxiality.