Production and chemical separation of ${}^{229}$Pa toward observation of $\gamma$ rays of ${}^{229\mathrm{m}}$Th

Abstract

To observe the $\gamma$ rays emitted from the low-lying isomeric state of ${}^{229}$Th (${}^{229\mathrm{m}}$Th), we aim to dope fluoride crystals with its precursor ${}^{229}$Pa. In this study, we produced ${}^{229}$Pa by a 30-MeV proton bombardment on ${}^{232}$Th and developed a chemical separation method. The chemical yield of Pa was 93(4)%, and the physical production yield of ${}^{229}$Pa for the proton energy range of 29.0$-$30.1 MeV was measured to be 9.4(8) MBq/$\mu$Ah, which was more than 10 times higher than those of ${}^{232,230,228,233}$Pa. These high chemical and production yields will allow us to prepare fluoride crystals having a sufficient amount of ${}^{229}$Pa for the observation of the $\gamma$ rays of ${}^{229\mathrm{m}}$Th.

References in corpus (7)

• Direct detection of the 229Th nuclear clock transition
• Enhanced effect of temporal variation of the fine structure constant in diatomic molecules
• Measurement of the ${}^{229}$Th isomer energy with a magnetic micro-calorimeter
• Lifetime measurement of the ${}^{229}$Th nuclear isomer
• Energy of the ${}^{229}$Th Nuclear Clock Isomer Determined by Absolute $\gamma$-ray Energy Difference
• ${}^{229m}$Th isomer from a nuclear model perspective
• Estimation of radiative half-life of ${}^{229m}$Th by half-life measurement of other nuclear excited states in ${}^{229}$Th