Anomalous Hyperfine Structure of the ${}^{229}$Th Ground-State Doublet in Muonic Atom

Abstract

The hyperfine splitting of the ground and low-energy $3/2^{+}(7.8\pm 0.5$ eV) levels in the ${}^{229}$Th nucleus in muonic atom (${\mu }_{1S_{1/2}}^{-}{}^{229}$Th${)}^{\ast }$ has been calculated considering the distribution of the nuclear magnetization in the framework of collective nuclear model with the wave functions of the Nilsson model for the unpaired neutron. It is shown that (a) the hyperfine splitting of the $3/2^{+}$ isomeric state is anomalously weak, and the reduction of hyperfine structure in comparison with the model of a point nuclear magnetic dipole is close to 100\%, (b) partial inversion of levels of the ${}^{229}$Th ground-state doublet and spontaneous decay of the ground state with excitation of the isomeric state take place, (c) the energy of the isomeric transition lies in the range of 120--140 eV, which makes possible the direct observation of the transition, registration of conversion electrons and measurement of the nuclear matrix element.

5 pages, 3 figures, 1 table

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
• Proposal for a Nuclear Gamma-Ray Laser of Optical Range
• Performance of a 229 Thorium solid-state nuclear clock
• Radiative lifetime and energy of the low-energy isomeric level in ${}^{229}$Th
• Systematics of nucleon density distributions and neutron skin of nuclei
• Radioluminescence and photoluminescence of Th:CaF${}_2$ crystals

Cited by in corpus (5)

• The ${}^{229}$Th isomer: prospects for a nuclear optical clock
• Excitation of ${}^{229m}$Th at Inelastic Scattering of Low Energy Electrons
• Ground-state $g$ factor of highly charged ${}^{229}$Th ions: an access to the M1 transition probability between the isomeric and ground nuclear states
• Internal conversion of the low energy ${}^{229m}$Th isomer in the Thorium anion
• Proposal for a Nuclear Light Source