F.F. Karpeshin, L.F. Vitushkin
D.I. Mendeleyev Institute for Metrology, St. Petersburg, Russia;
fkarpeshin@gmail.com
Al’manac of Modern Metrology № 2 (38) 2024, pages 19–29
Abstract. The most likely candidate for the role of the nuclear optical standard is the 8.338 eV isomer of the nuclear isotope 229mTh. The possibility of refining its energy using two-photon resonant optical pumping is discussed. Proper use of the natural atomic linewidths, which are orders of magnitude larger than the natural nuclear isomeric linewidth, is critical. In the modern state-of-the-art project, broadening due to internal conversion in neutral thorium atoms leads to a gain in scanning time by nine orders of magnitude, facilitating the search for electron-nuclear resonance to a practically feasible level. The two-photon resonance conversion method proposed in this article is applicable to both ionized and neutral thorium atoms. It has even greater potential: in the example considered, the atomic resonance at the 7p3/2 level has a width three orders of magnitude greater than the conversion line. The implementation of the proposed method requires simultaneous excitation of the core and electron shell in the final state with a high quality factor. The widespread use of various physics of the processes considered will predetermine a revolutionary leap in the development of new laser-nuclear technologies.
Keywords: isomer 229mTh, nuclear-optical clock, frequency standard.
Full texts of articles are available only in Russian in printed issues of the magazine.
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