Laser Excitation of the Th-229 NucleusONLINE ONLY

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The thorium-229 nucleus has a unique, low-lying isometric state allowing for laser spectroscopic investigations that are otherwise only accessible in electronic transitions. Here, we report on the first resonant laser excitation of the Th-229 nucleus with a tabletop tuneable laser system. The laser system consists of two seeded dye amplifiers that are frequency-converted via four-wave mixing in Xenon to the vacuum-ultraviolet (VUV) region. Using this light source, a resonance fluorescence signal in two CaF2 crystals with different Th-229 dopant concentrations is observed, while it is absent in a control experiment using Th-232. The nuclear resonance frequency of 2020.409(7) THz is measured with a fluorescence lifetime in the crystal of 630(15) s, corresponding to an isomer half-life of 1740(50) s for a nucleus isolated in vacuum. These results pave the way towards high-resolution nuclear laser spectroscopy of Th-229 and an optical nuclear clock with high sensitivity in fundamental tests.

Ref:

PRL 132, 182501 (2024)
This is work done in a cooperation of PTB and TU Wien by

J. Tiedau, M. V. Okhapkin, K. Zhang, J. Thielking, G. Zitzer, E. Peik
Physikalisch-Technische Bundesanstalt, Braunschweig

F. Schaden, T. Pronebner, I. Morawetz, L. Toscani De Col, F. Schneider, A. Leitner, M. Pressler, G. A. Kazakov, K. Beeks, T. Sikorsky, and T. Schumm
Vienna Center for Quantum Science and Technology, Atominstitut TU Wien

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