SMuK 2023 – wissenschaftliches Programm
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HK: Fachverband Physik der Hadronen und Kerne
HK 61: Structure and Dynamics of Nuclei XIII
HK 61.3: Vortrag
Donnerstag, 23. März 2023, 14:30–14:45, SCH/A117
Investigation of the internal conversion lifetime of 229mTh in a solid — •Lilli Löbell1, Sandro Kraemer1, Daniel Moritz1, Kevin Scharl1, Benedict Seiferle1, Lars von der Wense2, Florian Zacherl1, and Peter Thirolf1 — 1LMU München — 2Max-Planck-Institut für Quantenoptik, Garching
The first excited nuclear state of 229Th has an exceptionally low excitation energy of 8.338 ± 0.024 eV (λ = 148.71 ± 0.42 nm), allowing potentially a laser excitation of the nuclear transition. Consequently, 229Th is the so far only candidate for a nuclear clock, which can possibly outperform optical atomic clocks and be used amongst a manifold of other applications to investigate variations of fundamental constants. For the decay of the thorium isomer to the ground state, the dominant decay channel in neutral 229mTh atoms is internal conversion (IC), in which the nuclear transition energy is transferred to an electron of the atomic shell. The lifetime of the IC decay was measured on a metallic surface as 7 ± 1 µs, but there are indications of a dependence on the electronic environment surrounding the thorium atom. A possible way to investigate the IC lifetime within a solid state environment is the implantation of 229mTh atoms into the depletion region of a semiconductor detector, where the IC electrons can be detected. This could be a scenario for a solid-state nuclear clock where the clock transition would occur via IC in an active detector medium. The talk will present ongoing experiments using VUV-sensitive silicon photomultipliers for the IC electron detection. This work was supported by the European Research Council (ERC): ERC Synergy Grant ’ThoriumNuclearClock’.