SAMOP 2023 – wissenschaftliches Programm
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A: Fachverband Atomphysik
A 20: Poster II
A 20.2: Poster
Mittwoch, 8. März 2023, 16:30–19:00, Empore Lichthof
Towards high-resolution spectroscopy and direct laser excitation of thorium-229 — •Gregor Zitzer1, Johannes Tiedau1, Maksim Okhapkin1, Johannes Thielking1, Ke Zhang1, Christoph Mokry2,3, Jörg Runke2,4, Christoph E. Düllmann2,3,4, and Ekkehard Peik1 — 1Physikalisch-Technische Bundesanstalt — 2Department of Chemistry - TRIGA Site, Johannes Gutenberg University Mainz — 3Helmholtz Institute Mainz — 4GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt
Exciting the electronic levels of an atom with laser light is a well-established workhorse in atomic physics. Likewise, exciting the nuclear core of an atom with electromagnetic radiation is possible, although typical energies are in the keV to MeV range. Here, thorium-229, with a first excited state at only 8 eV excitation energy, is the only known exception that will allow excitation by coherent laser radiation. This unique feature promises advantages for optical clocks and for measurements to uncover physics beyond the standard model.
In our setup, thorium-229 ions are produced as recoil ions from the alpha decay of uranium-233, featuring a 2 % branching to the isomer. The recoil ions are slowed down in helium buffer gas, filtered, and transferred to a linear Paul trap, where they are cotrapped with strontium-88 ions for sympathetic cooling.
In addition, we show our latest progress on direct laser excitation with vacuum-ultraviolet light produced via four-wave-mixing in xenon, producing up to 40 µJ per pulse. As a proof of concept, we investigate atomic transitions of 232Th+ at 148 nm.