Theoretical predictions for the magnetic dipole moment of ${}^{229m}$Th

Abstract

A recent laser spectroscopy experiment [J. Thielking et al., Nature (London) 556, 321 (2018)] has determined for the first time the magnetic dipole moment of the 7.8 eV isomeric state ${}^{229m}$Th. The measured value differs by a factor of approximately 5 from previous nuclear theory predictions based on the Nilsson model, raising questions about our understanding of the underlying nuclear structure. Here, we present a new theoretical prediction based on a nuclear model with coupled collective quadrupole-octupole and single-particle motions. Our calculations yield an isomer magnetic dipole moment of ${\mu }_{IS}=-0.35{\mu }_N$ in surprisingly good agreement with the experimentally determined value of $-0.37(6){\mu }_N$, while overestimating the ground state dipole moment by a factor 1.4. The model provides further information on the states' parity mixing, the role and strength of the Coriolis mixing and the most probable value of the gyromagnetic ratio $g_R$ and its consequences for the transition probability $B(M1)$.

5 pages, 2 tables

References in corpus (9)

• Direct detection of the 229Th nuclear clock transition
• Enhanced effect of temporal variation of the fine structure constant in diatomic molecules
• Laser spectroscopic characterization of the nuclear clock isomer ${}^{229m}$Th
• Proposal for a Nuclear Gamma-Ray Laser of Optical Range
• Lifetime measurement of the ${}^{229}$Th nuclear isomer
• Nuclear clocks based on resonant excitation of gamma-transitions
• Nuclear collective motion with a coherent coupling interaction between quadrupole and octupole modes
• Non-yrast nuclear spectra in a model of coherent quadrupole-octupole motion
• Hyperfine interaction with the ${}^{229}$Th nucleus and its low lying isomeric state

Cited by in corpus (16)

• Sensitivity of ${}^{229}$Th nuclear clock transition to variation of the fine-structure constant
• Electronic bridge excitation in highly charged Th-229 ions
• Nuclear excitation of the ${}^{229}$Th isomer via defect states in doped crystals
• The ${}^{229}$Th isomer: prospects for a nuclear optical clock
• Concepts for direct frequency-comb spectroscopy of ${}^{229\text{m}}$Th and an internal-conversion-based solid-state nuclear clock
• The theory of direct laser excitation of nuclear transitions
• ${}^{229m}$Th isomer from a nuclear model perspective
• Ground-state $g$ factor of highly charged ${}^{229}$Th ions: an access to the M1 transition probability between the isomeric and ground nuclear states
• Tunable VUV Frequency Comb for ${}^{229m}$Th Nuclear Spectroscopy
• A scheme for excitation of thorium-229 nuclei based on the electronic bridge excitaion
• Driven electronic bridge processes via defect states in ${}^{229}$Th-doped crystals
• Nuclear coherent population transfer to the ${}^{229m}$Th isomer using x-ray pulses
• Relativistic coupled-cluster calculation of hyperfine-structure constants of ${}^{229}$Th${}^{3+}$ and evaluation of the electromagnetic nuclear moments of ${}^{229}$Th
• Magnetic moments of short-lived nuclei with part-per-million accuracy: Towards novel applications of $\beta$-detected NMR in physics, chemistry and biology
• Production and chemical separation of ${}^{229}$Pa toward observation of $\gamma$ rays of ${}^{229\mathrm{m}}$Th
• Comprehensive Assessment of ${\mathrm{Th}}^{3+}$ Properties for Nuclear Clock and Fundamental Physics Applications