Controlling <sup>229</sup>Th isomeric state population in a VUV transparent crystal.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39013899.
- Also identified by DOI 10.1038/s41467-024-49631-0 and PMC identifier 11252313.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
The radioisotope thorium-229 (<sup>229</sup>Th) is renowned for its extraordinarily low-energy, long-lived nuclear first-excited state. This isomeric state can be excited by vacuum ultraviolet (VUV) lasers and <sup>229</sup>Th has been proposed as a reference transition for ultra-precise nuclear clocks. To assess the feasibility and performance of the nuclear clock concept, time-controlled excitation and depopulation of the <sup>229</sup>Th isomer are imperative. Here we report the population of the <sup>229</sup>Th isomeric state through resonant X-ray pumping and detection of the radiative decay in a VUV transparent <sup>229</sup>Th-doped CaF<sub>2</sub> crystal. The decay half-life is measured to 447(25) s, with a transition wavelength of 148.18(42) nm and a radiative decay fraction consistent with unity. Furthermore, we report a new "X-ray quenching" effect which allows to de-populate the isomer on demand and effectively reduce the half-life. Such controlled quenching can be used to significantly speed up the interrogation cycle in future nuclear clock schemes.