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 (18)

• A Single-Ion Nuclear Clock for Metrology at the 19th Decimal Place
• Direct detection of the 229Th nuclear clock transition
• Enhanced effect of temporal variation of the fine structure constant in diatomic molecules
• Energy of the ${}^{229}$Th nuclear clock transition
• Laser spectroscopic characterization of the nuclear clock isomer ${}^{229m}$Th
• Observation of the radiative decay of the ${}^{229}\mathrm{Th}$ nuclear clock isomer
• Measurement of the ${}^{229}$Th isomer energy with a magnetic micro-calorimeter
• Lifetime measurement of the ${}^{229}$Th nuclear isomer
• X-ray pumping of the Th-229 nuclear clock isomer
• Radiative lifetime and energy of the low-energy isomeric level in ${}^{229}$Th
• Reduced transition probabilities for the gamma decay of the 7.8 eV isomer in ${}^{229}$Th
• Energy of the ${}^{229}$Th Nuclear Clock Isomer Determined by Absolute $\gamma$-ray Energy Difference
• On an attempt to optically excite the nuclear isomer in Th-229
• Radioluminescence and photoluminescence of Th:CaF${}_2$ crystals
• Theoretical predictions for the magnetic dipole moment of ${}^{229m}$Th
• ${}^{229m}$Th isomer from a nuclear model perspective
• An alternative approach to populate and study the ${}^{229}$Th nuclear clock isomer
• Estimation of radiative half-life of ${}^{229m}$Th by half-life measurement of other nuclear excited states in ${}^{229}$Th