Erlangen 2018 – scientific programme
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A: Fachverband Atomphysik
A 44: Precision Spectrosocopy VII (nuclear systems) (joint session A/Q)
A 44.3: Talk
Friday, March 9, 2018, 11:00–11:15, K 1.016
Laser spectroscopic characterization of the nuclear clock isomer 229mTh — •Johannes Thielking1, Maksim V. Okhapkin1, Przemysław Głowacki1, David-Marcel Meier1, Lars von der Wense2, Benedict Seiferle2, Christoph E. Düllmann3,4,5, Peter G. Thirolf2, and Ekkehard Peik1 — 1Physikalisch-Technische Bundesanstalt, 38116 Braunschweig, Germany — 2Ludwig-Maximilians-Universität München, 85748 Garching, Germany — 3GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt, Germany — 4Helmholtz-Institut Mainz, 55099 Mainz, Germany — 5Johannes Gutenberg-Universität, 55099 Mainz, Germany
The thorium-229 nucleus possesses a unique first excited state at an energy of only about 7.8 eV, coupled to the ground state by a transition with a natural linewidth in the mHz range. This transition can be used as a reference for an optical clock that is highly immune to field-induced frequency shifts and as a sensitive probe of temporal variations of fundamental constants. Despite many experimental efforts, fundamental properties of the isomer were still unknown. In this presentation we report on the first measurement of the nuclear moments and the mean square charge radius of the isomer [1]. This was achieved via high-resolution spectroscopy of the hyperfine structure of trapped 229Th2+ ions using two-step laser excitation. Our results yield a key feature in the ongoing experimental search for the direct optical excitation of the nuclear transition, as well as the future nuclear clock operation.
[1] J. Thielking et al., arXiv preprint arXiv:1709.05325 (2017).