X-Ray-Induced Quenching of the Th²⁹⁹ Clock Isomer in CaF₂

Abstract

Recent studies have shown that the lifetime of the isomeric ²⁹⁹Th 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 in²⁹⁹T: 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.