Octupole deformations in high-Kisomeric states of heavy and superheavy nuclei

N Minkov,P M Walker

doi:10.1051/epjconf/201610703008

N Minkov, P M Walker

Open Access

https://doi.org/10.1051/epjconf/201610703008

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Abstract

We study the effects of quadrupole-octupole deformations on the energy and magnetic properties of high-K isomeric states in even-even heavy and superheavy nuclei. The neutron two-quasiparticle (2qp) isomeric energies and magnetic dipole moments are calculated within a deformed shell model with the Bardeen-Cooper- Schrieffer (BCS) pairing interaction over a wide range of quadrupole and octupole deformations. We found that in most cases the magnetic moments exhibit a pronounced sensitivity to the octupole deformation, while the 2qp energies indicate regions of nuclei in which the presence of high-K isomeric states may be associated with the presence of octupole softness or even with octupole deformation. In the present work we also examine the influence of the BCS pairing strength on the energy of the blocked isomer configuration. We show that the formation of 2qp energy minima in the space of quadrupole-octupole and eventually higher multipolarity deformations is a subtle effect depending on nuclear pairing correlations.

Highlights

IntroductionFirst we illustrate the evolution of the 2qp energy minima for high-K isomeric states of heavy even-even nuclei calculated within the deformed shell model (DSM)+BCS approach without blocking the excited 2qp configuration in the BCS procedure
We found that in most cases the magnetic moments exhibit a pronounced sensitivity to the octupole deformation, while the 2qp energies indicate regions of nuclei in which the presence of high-K isomeric states may be associated with the presence of octupole softness or even with octupole deformation
The implemented deformed shell model (DSM)+BCS calculations suggest that octupole deformation may play a considerable role in the formation of two-quasiparticle high-K isomeric states in even-even heavy and superheavy nuclei

Summary

Introduction

First we illustrate the evolution of the 2qp energy minima for high-K isomeric states of heavy even-even nuclei calculated within the DSM+BCS approach without blocking the excited 2qp configuration in the BCS procedure. After that we show the result of calculations performed in 254No and 270Ds by blocking the two excited orbitals and by varying the BCS pairing strength. As will be seen below, this allows us to assess the roles of the blocking effect and the pairing strength in the appearance of 2qp energy minima in the quadrupoleoctupole deformation space. We are able to estimate the predictive value of the theoretical results which suggest different regions of deformation with possible formation of high-K isomeric states.

Deformed shell model with pairing interaction

Numerical results and discussion

Summary