2026-01-09 岡山大学,高輝度光科学研究センター,京都大学,理化学研究所,大阪大学
図1 (a) トリウム229準位図（関係する基底状態及び励起状態）。(b) X線照射時間に対する生成アイソマー数の増加の測定データ。室温(36℃)と低温(-120℃)の比較。
＜関連情報＞
- https://www.okayama-u.ac.jp/tp/release/release_id1484.html
- https://www.okayama-u.ac.jp/up_load_files/press_r7/press20260109-1.pdf
- https://journals.aps.org/prl/abstract/10.1103/75bb-thn7
X線誘起消光229Th時計異性体CaF2 X-Ray-Induced Quenching of the 229Th Clock Isomer in CaF2
Ming Guan, Michael Bartokos, Kjeld Beeks, Hiroyuki Fujimoto, Yuta Fukunaga, Hiromitsu Haba, Takahiro Hiraki, Yoshitaka Kasamatsu, Shinji Kitao et al.
Physical Review Letters Published: 8 January, 2026
DOI: https://doi.org/10.1103/75bb-thn7
Abstract
Recent studies have shown that the lifetime of the isomeric 229Th 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 229Th:CaF2 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.
