# Heidelberg 2015 – wissenschaftliches Programm

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# A: Fachverband Atomphysik

## A 13: Precision spectroscopy of atoms and ions II (with Q)

### A 13.5: Vortrag

### Dienstag, 24. März 2015, 12:15–12:30, M/HS1

**A high-precision measurement of the isotope effect in the magnetic moment of highly charged **^{40,48}**Ca**^{17+}** ions** — •Jiamin Hou^{1}, Florian Köhler^{1,2}, Sven Sturm^{1}, Anke Wagner^{1}, Wolfgang Quint^{2}, Günter Werth^{3}, and Klaus Blaum^{1} — ^{1}MPIK, Heidelberg, Germany — ^{2}GSI, Darmstadt, Germany — ^{3}JGU, Mainz, Germany

To achieve a comprehensive understanding of the fundamental properties of nature, high-precision experiments with trapped charged particles are one of the most promising methods.
In this experiment, the magnetic moments, i.e. *g*-factors, of the bound electrons for lithium-like ^{40}Ca and ^{48}Ca ions in the medium Z region (Z=20) have been measured for the first time with a relative uncertainty of 7·10^{−10}, giving rise to a stringent test of the isotope effect. We determine the bound-state electron magnetic moment by measuring the ratio of the electron spin-precession frequency and the ion’s cyclotron frequency^{1,2} in a cryogenic Penning-trap apparatus. The final result is obtained by combining our results with state-of-the-art QED calculations and an independent Penning-trap mass measurement. In the next step, hydrogen-like ^{40,48}Ca^{19+} will be studied. The comparison with the lithium-like system allows us to separate nuclear and inter-electronic effects. Furthermore, a novel trap system is under development which will push the achievable precision into the 10^{−12} regime and thus will open new possibilities for the determination of fundamental constants.

[1] A.Wagner et al. Phys. Rev. Lett. 110, 033003 (2013)

[2] S. Sturm et al. Phys. Rev. Lett. 107, 023002(2011)