$g$-factor of Boronlike Argon ${}^{40}{\text{Ar}}^{13+}$

Abstract

We have measured the ground-state $g$-factor of boronlike argon ${}^{40}{\text{Ar}}^{13+}$ with a fractional uncertainty of \SI{1.4e-9}{} with a single ion in the newly developed ALPHATRAP double Penning-trap setup. The here obtained value of $g=0.66364845532(93)$ is in agreement with our theoretical prediction of $0.66364812(58)$. The latter is obtained accounting for quantum electrodynamics, electron correlation, and nuclear effects within the state-of-the-art theoretical methods. Our experimental result distinguishes between existing predictions that are in disagreement, and lays the foundations for an independent determination of the fine-structure constant.

6 pages, 3 figures, 2 tables