Direct Evidence for Octupole Deformation in Ba 146 and the Origin of Large E1 Moment Variations in Reflection-Asymmetric Nuclei

Despite the more than 1 order of magnitude difference between the measured dipole moments in Ba144 and Ba146, the octupole correlations in Ba146 are found to be as strong as those in Ba144 with a similarly large value of B(E3;3-→0+) determined as 48(+21-29) W.u. The new results not only establish unambiguously the presence of a region of octupole deformation centered on these neutron-rich Ba isotopes, but also manifest the dependence of the electric dipole moments on the occupancy of different neutron orbitals in nuclei with enhanced octupole strength, as revealed by fully microscopic calculations.