Rostock 2019 – wissenschaftliches Programm
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A: Fachverband Atomphysik
A 18: Precision Spectroscopy of atoms and ions V (Th 229)
A 18.1: Vortrag
Mittwoch, 13. März 2019, 14:00–14:15, S HS 2 Physik
Excitation of 229Th2+ with a two-photon electron transition — •Robert A. Müller1,2, Andrey V. Volotka3, Stephan Fritzsche2,4, and Andrey Surzhykov1,2 — 1Physikalisch-Technische Bundesanstalt, Germany — 2Technische Universität Braunschweig, Germany — 3Helmholtz-Institute Jena, Germany — 4Friedrich-Schiller-Universität Jena, Germany
About one decade ago a clock based on the optical nuclear transition in 229Th has been proposed [1]. For this purpose many mechanisms to excite the 229Th nucleus have been discussed. In particular such processes involving an energy transfer from electronic transitions to the nucleus are expected to be very efficient. There is, however, a major drawback that comes with these so-called electron bridge processes: The electronic transition has to be in resonance with the nuclear one. To overcome this problem we propose the process of nuclear excitation by a two-photon transition (NETP) to excite the 229Th nucleus. In this process the electron shell deexcites via the emission of two photons, where one of them is emitted and the other one excites the nucleus. We employ a combination of configuration interaction and many-body perturbation theory to calculate the NETP probability in resonance approximation. With these calculations we propose a circular process consisting of a pumping stage and subsequent NETP. In particular we make recommendations wich electron level to pump to achieve the highest NETP probability.
[1] E. Peik and C. Tamm, Europhys. Lett. 61, 181 (2003)