Magnetic hyperfine structure of the ground-state doublet in highly charged ions $^{229}$Th$^{89+,87+}$ and the Bohr-Weisskopf effect

摘要

The magnetic hyperfine (MHF) structure of the $5/2^+$(0.0 eV) ground stateand the low-lying $3/2^+$(7.8 eV) isomeric state of the $^{229}$Th nucleus inhighly charged ions Th$^{89+}$ and Th$^{87+}$ is calculated. The distributionof the nuclear magnetization (the Bohr-Weisskopf effect) is accounted for inthe framework of the collective nuclear model with the wave functions of theNilsson model for the unpaired neutron. The deviations of the MHF structure forthe ground and isomeric states from their values in the model of point-likenuclear magnetic dipole are calculated. The influence of the mixing of thestates with the same quantum number $F$ on the energy of sublevels is studied.Taking into account the mixing of states, the probabilities of the transitionsbetween the components of MHF structure are found.