Excitation of the $^{229}$Th nucleus by the hole in the inner electronic shells

M. G. Kozlov; A. V. Oleynichenko; D. Budker; D. A. Glazov; Y. V. Lomachuk; V. M. Shabaev; A. V. Titov; I. I. Tupitsyn; A. V. Volotka

arXiv · 2308.05173

Excitation of the $^{229}$Th nucleus by the hole in the inner electronic shells

M. G. Kozlov·A. V. Oleynichenko·D. Budker·D. A. Glazov·Y. V. Lomachuk·V. M. Shabaev·A. V. Titov·I. I. Tupitsyn·A. V. Volotka

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Abstract

The $^{229}$Th nucleus has a long-lived isomeric state $A^*$ at 8.338(24) eV [Kraemer et al, Nature, \textbf{617}, 706 (2023)]. This state is connected to the ground state by an M1 transition. For a hydrogenlike Th ion in the $1s$ state the hyperfine structure splitting is about 0.7 eV. This means that the hyperfine interaction can mix the nuclear ground state with the isomeric state with a mixing coefficient $β$ about 0.03. If the electron is suddenly removed from this system, the nucleus will be left in the mixed state. The probability to find the nucleus in the isomeric state $A^*$ is equal to $β^2\sim 10^{-3}$. For the $2s$ state the effect is roughly two orders of magnitude smaller. An atom with a hole in the $1s$ or $2s$ shell is similar to the hydrogenlike atom, only the hole has a short lifetime $τ$. After the hole is filled, there is a non-zero probability to find the nucleus in the $A^*$ state. Estimates of this probability are presented along with a discussion of possible experiments on Th-doped xenotime-type orthophosphate crystals and other broad band gap materials.

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M. G. Kozlov, A. V. Oleynichenko, D. Budker, D. A. Glazov, Y. V. Lomachuk, V. M. Shabaev, A. V. Titov, I. I. Tupitsyn, A. V. Volotka. 2024-03-01. Excitation of the $^{229}$Th nucleus by the hole in the inner electronic shells. https://arxiv.org/abs/2308.05173

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