Anomalous magnetic hyperfine structure of the Th-229 ground-state doublet in muonic atoms

摘要

The magnetic hyperfine (MHF) splitting of the ground and low-energy 3/2(+) (7.8 +/- 0.5 eV) levels in the Th-229 nucleus in the muonic atom (mu(-)(1S1/2) Th-229)* is calculated considering the distribution of the nuclear magnetization in the framework of the collective nuclear model with wave functions of the Nilsson model for the unpaired neutron. It is shown that (a) deviation of the MHF structure of the isomeric state exceeds 100% from its value for a pointlike nuclear magnetic dipole (the order of sublevels is reversed); (b) partial inversion of levels of the 229Th ground-state doublet and spontaneous decay of the ground state to the isomeric state occur; (c) the E0 transition, which is sensitive to differences in the mean-square charge radii of the doublet states, is possible between mixed sublevels with F = 2; and (d) MHF splitting of the 3/2(+) isomeric state may be in the optical range for certain values of the intrinsic g(K) factor and a reduced probability of a nuclear transition between the isomeric and the ground states.