Radiative decay and electromagnetic moments in ${}^{229}$Th determined within nuclear DFT

Abstract

Using the nuclear DFT approach with symmetry breaking and restoration, we investigate the electromagnetic properties of the ground and isomeric states in ${}^{229}$Th. We determine the magnetic dipole transition strength B(M1; $3/2_1^{+}\to 5/2_1^{+})$ between these two states and discuss the effects of parity breaking, configuration mixing, and time-odd core polarization. We also determine the corresponding spectroscopic magnetic dipole and octupole, and electric quadrupole moments. Because the octupole deformability of the Skyrme functionals used here is not described in sufficient detail, we analyze the results using a set of Skyrme functionals and perform a regression aligned with the measured electric octupole moments of neighboring even-even nuclei. Without parameter adjustment, the results compare favorably with the experimental data but also indicate the need to systematically adjust the octupole degrees of freedom in future functional parametrizations.

15 pages, 13 figures, 5 tables, includes Supplemental Material, results for the magnetic octupole added