Absolute measurement of the relativistic magnetic dipole transition in He-like sulfur

TL;DR

This paper reports the first absolute measurement of a relativistic magnetic dipole transition in He-like sulfur, providing a critical test of quantum electrodynamics and atomic structure calculations in medium-Z ions.

Contribution

It presents the first reference-free, high-precision measurement of the 1s2s 3 S1 to 1s 2 1 S0 transition in He-like sulfur, comparing results with advanced QED calculations.

Findings

Transition energy measured as 2430.3685(97) eV.

No significant dependence on silicon crystal form factor models.

Provides a benchmark for two-electron QED effects in medium-Z ions.

Abstract

We have made the first absolute, reference-free measurement of the 1s2s 3 S1 $\rightarrow$ 1s 2 1 S0 relativistic magnetic dipole transition in He-like sulfur. The highly-charged S ions were provided by an electron-cyclotron resonance ion source, and the x rays were analysed with a high-precision double crystal spectrometer. A transition energy of 2430.3685(97) eV was obtained, and is compared to most advanced bound state quantum electrodynamics calculations, providing an important test of two-electron QED effects and precision atomic structure methods in medium-Z species. Thanks to the extremely narrow natural linewidth of this transition, and to the large dispersion of the spectrometer at this energy, a complementary study was also performed evaluating the impact of different silicon crystal atomic form factor models in the transition energy analysis. We find no significant dependence on the model used to determine the transition energy.