EGAS41 - Swansea University

41 st EGAS CP 18 Gdańsk 2009
Search for the frequencies for the nuclear optical clock with the
use of information from the analysis of the fine structure of high
lying energy levels in Th + ion
J. Dembczyński ∗ , J. Ruczkowski, M. Elantkowska
Chair of Quantum Engieneering and Metrology, Poznań University of Technology Nieszawska
13B, PL 60-965 Poznań, Poland
∗ Corresponding author: jerzy.dembczynski@put.poznan.pl
The nucleus of 229 Th has the very low energy (7.6 eV) of excitation [1]. Therefore, it is
possible to use this system to establish nuclear laser spectroscopy and eventually to built
a nuclear optical clock of very high accuracy [2,3].
The Th + ion has a very high density of electronic states. According to suggestion of
prof. E.Peik, the electronic excitation can be used as a kind of ”antenna” to increase
the coupling of laser light to the small nuclear moments (nuclear excitation via electron
transition)[4]. The efficiency of these processes depends on resonance conditions, i.e.
the availability of electronic states near the nuclear excitation. Available information on
energy levels and lines of Th + is restricted to values below 60000 cm −1 , based on the
analysis of 13 three-electron configurations involving 5f, 6d, 7s and 7p electrons [5].
In our semiempirical calculations, based on the experimental data, we determine the
even and odd parity level scheme of Th + ion in the range up to about 75000 cm −1 , taking
into account higher excited electron configurations. Using the fine structure eigenvectors,
determination of the transition probabilities for the allowed transitions will be possible.
Acknowledgment
This work was supported by Polish Ministry of Science and Higher Education under the project
N519 033 32/4065.
References
[1] B.R. Beck et al., Phys. Rev. Lett. 98, 142501 (2007)
[2] E. Peik, Chr. Tamm, Europhys. Lett., 61 (2), 181 (2003)
[3] E. Peik, K. Zimmermann, M. Okhapkin, Chr. Tamm, arXiv:0812.3548v2 (2009)
[4] E. Peik, private communication
[5] http://www.lac.u-psud.fr/Database/Tab-energy/Thorium/Th-el-dir.html
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