Exploring $\hat{I}\pm$- and ${\hat{I}}^2$-decay-induced quenching of the ${}^{229}$Th nuclear-clock isomer in solid-state hosts

Abstract

The radiative decay dynamics of an ensemble of ${}^{229\mathrm{m}}$Th nuclei embedded in CaF${}_2$ and MgF${}_2$ is investigated. The isomer is populated through ${\hat{I}}^2$ decay of ${}^{229}$Ac following ion implantation, and its radiative decay is detected using vacuum-ultraviolet spectroscopy and measured as a function of time. This allows to identify and quantify the quenching of the radiative-decay signal induced by $\hat{I}\pm$ or ${\hat{I}}^2$ radiation. The quenching probability density is determined in different CaF${}_2$ crystals and in a MgF${}_2$ crystal, revealing differences up to two orders of magnitude between the investigated samples and a strong dependence on the host material and defect densities. The results support a microscopic mechanism mediated by charge carriers in which electronic excitations created by the decay radiation are captured near Th defects, thereby favoring non-radiative decay channels.

13 pages main text and 2 pages supplemental material. Main text contains 7 figures, supplementary material 1