${}^{229m}$Th isomer from a nuclear model perspective

Abstract

The physical conditions for the emergence of the extremely low-lying nuclear isomer ${}^{229m}$Th at approximately 8 eV are investigated in the framework of our recently proposed nuclear structure model. Our theoretical approach explains the ${}^{229m}$Th-isomer phenomenon as the result of a very fine interplay between collective quadrupole-octupole and single-particle dynamics in the nucleus. We find that the isomeric state can only appear in a rather limited model space of quadrupole-octupole deformations in the single-particle potential, with the octupole deformation being of a crucial importance for its formation. Within this deformation space the model-described quantities exhibit a rather smooth behaviour close to the line of isomer-ground state quasi-degeneracy determined by the crossing of the corresponding single-particle orbitals. Our comprehensive analysis confirms the previous model predictions for reduced transition probabilities and the isomer magnetic moment, while showing a possibility for limited variation in the ground-state magnetic moment theoretical value. These findings prove the reliability of the model and suggest that the same dynamical mechanism could manifest in other actinide nuclei giving a general prescription for the search and exploration of similar isomer phenomena.

22 pages, 14 figures

References in corpus (22)

• Relativistic Nuclear Energy Density Functionals: adjusting parameters to binding energies
• 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
• Proposal for a Nuclear Gamma-Ray Laser of Optical Range
• Measurement of the ${}^{229}$Th isomer energy with a magnetic micro-calorimeter
• Lifetime measurement of the ${}^{229}$Th nuclear isomer
• Microscopic description of octupole shape-phase transitions in light actinides and rare-earth nuclei
• A proposed experimental method to determine $\alpha$-sensitivity of splitting between ground and 7.6 eV isomeric states in Th-229
• Nuclear clocks based on resonant excitation of gamma-transitions
• 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
• Sensitivity of ${}^{229}$Th nuclear clock transition to variation of the fine-structure constant
• Energy of the ${}^{229}$Th Nuclear Clock Isomer Determined by Absolute $\gamma$-ray Energy Difference
• Nuclear collective motion with a coherent coupling interaction between quadrupole and octupole modes
• Magnetic dipole and electric quadrupole moments of the 229Th nucleus
• Non-yrast nuclear spectra in a model of coherent quadrupole-octupole motion
• Theoretical predictions for the magnetic dipole moment of ${}^{229m}$Th
• Hyperfine interaction with the ${}^{229}$Th nucleus and its low lying isomeric state
• Non-yrast spectra of odd-A nuclei in a model of coherent quadrupole-octupole motion

Cited by in corpus (9)

• Expanding Nuclear Physics Horizons with the Gamma Factory
• Precision calculation of hyperfine constants for extracting nuclear moments of 229Th
• Ground-state $g$ factor of highly charged ${}^{229}$Th ions: an access to the M1 transition probability between the isomeric and ground nuclear states
• Recollision induced nuclear excitation of ${}^{229}$Th
• 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
• Estimation of radiative half-life of ${}^{229m}$Th by half-life measurement of other nuclear excited states in ${}^{229}$Th
• Production and chemical separation of ${}^{229}$Pa toward observation of $\gamma$ rays of ${}^{229\mathrm{m}}$Th
• Probing New Forces with Nuclear Clocks