X-Ray-Induced Quenching of the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mmultiscripts><mrow><mi>Th</mi></mrow><mprescripts></mprescripts><none></none><mrow><mn>229</mn></mrow></mmultiscripts></mrow></math> Clock Isomer in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>CaF</mi></mrow><mrow><mn>2</mn></mrow></msub></mrow></math>

Ming Guan; Michael Bartokos; Kjeld Beeks; Hiroyuki Fujimoto; Yuta Fukunaga; Hiromitsu Haba; Takahiro Hiraki; Yoshitaka Kasamatsu; Shinji Kitao; Adrian Leitner; Takahiko Masuda; Nobumoto Nagasawa; Koichi Okai; Ryoichiro Ogake; Martin Pimon; Martin Pressler; Noboru Sasao; Fabian Schaden; Thorsten Schumm; Makoto Seto; Yudai Shigekawa; Kotaro Shimizu; Tomas Sikorsky; Kenji Tamasaku; Sayuri Takatori; Tsukasa Watanabe; Atsushi Yamaguchi; Yoshitaka Yoda; Akihiro Yoshimi; Koji Yoshimura

doi:10.1103/75bb-thn7

X-Ray-Induced Quenching of the ${}^{229}{Th}$ Clock Isomer in ${CaF}_{2}$

Ming Guan ^1,*,‡, Michael Bartokos ², Kjeld Beeks ², Hiroyuki Fujimoto ³, Yuta Fukunaga¹, Hiromitsu Haba⁴, Takahiro Hiraki ¹, Yoshitaka Kasamatsu⁵, Shinji Kitao ⁶ et al.

Adrian Leitner², Takahiko Masuda ¹, Nobumoto Nagasawa ⁷, Koichi Okai¹, Ryoichiro Ogake¹, Martin Pimon ², Martin Pressler², Noboru Sasao¹, Fabian Schaden ², Thorsten Schumm ², Makoto Seto ⁶, Yudai Shigekawa ⁴, Kotaro Shimizu¹, Tomas Sikorsky², Kenji Tamasaku⁸, Sayuri Takatori ¹, Tsukasa Watanabe³, Atsushi Yamaguchi ⁹, Yoshitaka Yoda ⁷, Akihiro Yoshimi ^1,†, and Koji Yoshimura¹

¹Research Institute for Interdisciplinary Science, Okayama University, Okayama 700-8530, Japan
²Institute for Atomic and Subatomic Physics, Atominstitut, TU Wien, Vienna 1020, Austria
³National Institute of Advanced Industrial Science and Technology (AIST), Ibaraki 305-8563, Japan
⁴Nishina Center for Accelerator-Based Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
⁵Graduate School of Science, The University of Osaka, Toyonaka, Osaka 560-0043, Japan
⁶Institute for Integrated Radiation and Nuclear Science, Kyoto University, Osaka 590-0494, Japan
⁷Japan Synchrotron Radiation Research Insitute, Kouto, Hyogo 679-5198, Japan
⁸RIKEN SPring-8 Center, Kouto, Hyogo 679-5148, Japan
⁹RIKEN Center for Advanced Photonics, Wako, Saitama 351-0198, Japan

^*Contact author: guanming@apm.ac.cn
^†Contact author: yoshimi@okayama-u.ac.jp
^‡Present address: Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China.

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Phys. Rev. Lett. 136, 013203 – Published 8 January, 2026

DOI: https://doi.org/10.1103/75bb-thn7

Abstract

Recent studies have shown that the lifetime of the isomeric ${}^{229}{Th}$ doped in crystals can be shortened by x-ray or laser irradiation, a phenomenon referred to as isomer quenching. We investigate the temperature dependence of x-ray-induced quenching in ${}^{229}{Th} : {CaF}_{2}$ and identify a correlation with the afterglow of the host crystal. These results suggest a mechanism in which x-ray-induced electrons migrate through the lattice and are captured at Th sites, enabling isomer deexcitation via internal conversion through electron–nucleus coupling. This mechanism links nuclear decay to charge carrier dynamics in the host crystal, providing a new interface between nuclear and solid-state physics. The findings offer a pathway to optimize the performance of solid-state nuclear clocks.

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X-Ray-Induced Quenching of the ${}^{229}{Th}$ Clock Isomer in ${CaF}_{2}$

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X-Ray-Induced Quenching of the Th229 Clock Isomer in CaF2

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X-Ray-Induced Quenching of the ${}^{229}{Th}$ Clock Isomer in ${CaF}_{2}$