Modelling hyperfine interactions for nuclear g-factor measurements

B P Mccormick,A E Stuchbery,A Kusoglu,G Georgiev,A Goasduff

doi:10.1051/epjconf/202023204009

Abstract

A promising technique forg-factor measurements on short-lived nuclear states utilises the hyperfine fields of free ions in vacuum. To fully utilise this technique the hyperfine interaction must be modelled based on atomic structure calculations. Atomic structure calculations were performed using the most recent release of the General Relativistic Atomic Structure Package, and Monte-Carlo simulations of atomic-decay cascades in highly charged ions were developed. The simulations were used to fit experimental data on excited56Fe ions recoiling in vacuum with a view to determining the first-excited state g factor, g(21+), of56Fe.

Highlights

A powerful probe for nuclear structure study is the magnetic dipole moment, μ
To tackle the challenge of identifying these important atomic configurations, we model the hyperfine interaction by performing atomic structure calculations and evaluating the effect of atomic transitions in an ensemble of charge states by the Monte-Carlo method [9, 10]
The charge-state distributions of 56Fe ions traversing nickel foils at various energies were measured at the Australian National University (ANU) Heavy Ion Accelerator Facility (HIAF) [15]

Summary

Introduction

A powerful probe for nuclear structure study is the magnetic dipole moment, μ. The g factor provides a way to probe the wavefunction of a single state. It is sensitive to the composition of broken proton vs neutron pairs, and the angular momentum they carry. Often, these states have lifetimes in the picosecond range, requiring kiloteslastrength fields to perform g-factor measurements. These states have lifetimes in the picosecond range, requiring kiloteslastrength fields to perform g-factor measurements Such fields can only result from hyperfine interactions. The hyperfine interaction, which depends on the g factor, perturbs the distribution of γ rays from the nuclei. After the transient-field effect was discovered, it became the primarily used method to measure the g factors of short-lived states from the mid-1970s onward

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