Measuring the Th-229 nuclear isomer transition with U-233 doped crystals

Abstract

We propose a simple approach to measure the energy of the few-eV isomeric state in Th-229. To this end, U-229 nuclei are doped into VUV-transparent crystals, where they undergo alpha decay into Th-229, and, with a probability of 2%, populate the isomeric state. These Th-229m nuclei may decay into the nuclear ground state under emission of the sought-after VUV gamma, whose wavelength can be determined with a spectrometer. Based on measurements of the optical transmission of U:CaF2 crystals in the VUV range, we expect a signal at least 2 orders of magnitude larger compared to current schemes using surface-implantation of recoil nuclei. The signal background is dominated by Cherenkov radiation induced by beta decays of the thorium decay chain. We estimate that, even if the isomer undergoes radiative de-excitation with a probability of only 0.1%, the VUV gamma can be detected within a reasonable measurement time.

arXiv comment5+7 pages, 4+3 figures, 7 tables

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Cited by in corpus (11)

• Observation of the radiative decay of the ${}^{229}\mathrm{Th}$ nuclear clock isomer
• Lifetime measurement of the ${}^{229}$Th nuclear isomer
• A laser excitation scheme for ${}^{229\text{m}}$Th
• The ${}^{229}$Th isomer: prospects for a nuclear optical clock
• On an attempt to optically excite the nuclear isomer in Th-229
• An alternative approach to populate and study the ${}^{229}$Th nuclear clock isomer
• Towards a 229Th-based nuclear clock
• Internal conversion from excited electronic states of ${}^{229}\mathrm{T}h$ ions
• Driven electronic bridge processes via defect states in ${}^{229}$Th-doped crystals
• Feasibility Study of Internal Conversion Electron Spectroscopy of ${}^{229m}$Th
• Towards an energy measurement of the internal conversion electron in the de-excitation of the Th-229 isomer