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キーワード:
-
MPINP:
Research group A. Pálffy – Division C. H. Keitel
要旨:
The 229Th nucleus with its 7.8 eV isomeric state is a unique candidate for the first nuclear
optical clock at an exceptional accuracy of 10−19. Due to the low isomeric transition
energy, the coupling to the atomic shell in the processes of internal conversion (IC) or
electron bridge (EB) is very strong. In this work we investigate theoretically the IC and
EB mechanisms and design novel laser-assisted schemes aimed at (i) a more accurate
determination of the isomer energy Em and (ii) efficient excitation of the isomer. On
the one hand, we show how IC occurring from excited electronic states of Th ions can
be used to determine the isomeric transition energy. We also propose a new approach
to measure the isomer energy with laser spectroscopy accuracy via laser-induced EB in
229Th3+ ions. On the other hand, we put forward possible isomer excitation schemes
based on the EB process in highly charged Th ions or on laser-assisted nuclear excitation
by electron capture of the 29.19 keV nuclear state lying directly above the isomer. Our
results show that EB in highly charged ions which allow optical driving with high-power
lasers should lead to efficient excitation. Such a setup using ion traps might become
relevant for the future development of the nuclear clock.
