Mainz 2026 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 84: Precision Spectroscopy of Atoms and Ions VI (joint session A/Q)
Q 84.1: Talk
Friday, March 6, 2026, 14:30–14:45, N 3
Towards a direct g-factor difference measurement of 12,14C5+ — •Max Anton Gramberg1, Matthew Bohman1, Emily Burbach2, Fabian Heiße1, Philipp Justus1, Kristian König2, Jialin Liu1, Wilfried Nörtershäuser2, Sven Sturm1, and Klaus Blaum1 — 1MPIK, Heidelberg — 2IKP, TU Darmstadt, Darmstadt
ALPHATRAP [1] is a cryogenic Penning-trap apparatus for high-precision measurements. By confining single ions in ultra-stable electromagnetic fields, g-factor determinations at the sub-ppb level are enabled, offering stringent tests of quantum electrodynamics in extreme fields. Even higher precision was reached by measuring the direct g-factor difference of 20,22Ne9+-ions co-trapped in a Penning trap [2]. In such coherent difference measurements otherwise unavoidable fluctuations of the magnetic field are largely suppressed, allowing to reach sub-ppt accuracy.
The planned measurement of the isotopic shift of the bound electron g-factor between 12C5+ and 14C5+ provides a unique opportunity for fundamental atomic physics. The lower nuclear charge Z enables an even more precise prediction by QED calculations and, when combined with the potentially improved precision in our recently upgraded apparatus, can be used to set competitive bounds on scalar dark matter candidates. Conversely, our planned measurement can also be used to extract an ultra precise charge radius difference and so benchmark other radius extraction methods as well as ab-initio nuclear theory.
[1] S. Sturm, et al. Eur. Phys. J. Spec. Top. 227, 1425-1491 (2019). [2] T. Sailer, V. Debierre, et al. Nature 606, 479-483 (2022).
Keywords: precision measurements; Penning traps; g-factors; highly charged ions; nuclear structure