Reliability test for the experimental results of electric quadrupole hyperfine structure constants and new assessment of nuclear quadrupole moments in $^{135,137}$Ba

TL;DR

This study assesses the reliability of experimental hyperfine structure constants in barium isotopes, identifies inconsistencies, and provides revised nuclear quadrupole moment values using advanced relativistic many-body calculations.

Contribution

It introduces a comprehensive reliability test for experimental hyperfine constants and offers new nuclear quadrupole moment estimates based on relativistic coupled-cluster theory.

Findings

Inconsistencies found in experimental $B$ values across different studies.

Revised nuclear quadrupole moments for $^{135}$Ba and $^{137}$Ba differ by about 4% from previous values.

Confidence tests highlight the need for careful validation of hyperfine structure measurements.

Abstract

We investigate electric quadrupole hyperfine structure constant ($B$) results in $^{135}$Ba$^+$ and $^{137}$Ba$^+$ and compare their ratios with the reported measurements of the ratio between the nuclear quadrupole moment ($Q$) values of these isotopes. We carry out confidence tests for the reported experimental $B$ values and calculations of $B/Q$ from the present work. Inconsistencies in the experimental $B$ values are observed in both the isotopes from different experiments performed using the same techniques. The present calculations are carried out using an all order relativistic many-body theory considering only single and double excitations in the coupled-cluster ansatz. After a detailed analysis of the results, the values of $Q$ we obtain for $^{135}$Ba and $^{137}$Ba are 0.153(2)$b$ and 0.236(3)$b$, respectively, which differ by about 4% from the currently referred precise values.