One- and two-phonon gamma-vibrational bands in neutron-rich Mo-107

摘要

Neutron-rich Mo-107 has been reinvestigated by analyzing the large statistics gamma-gamma-gamma and gamma-gamma-gamma-gamma coincidence data from the spontaneous fission of Cf-252 at the Gammasphere detector array. Two new bands have been identified. The potential-energy surface calculations of this nucleus have been performed. The calculations show evidence for the 5/2(+)[413] configuration of the ground-state band and 7/2(-)[523] configuration for the 348-keV excited band, as assigned in previous work. The two bands newly established are proposed to be one- and two-phonon gamma-vibrational bands built on the 7/2(-)[523] Nilsson orbital, respectively, in the current paper. Triaxial projected shell-model (TPSM) calculations have been performed to explain the level structure and are found in fair agreement with experimental data. In particular, the TPSM study confirms the gamma- and gamma gamma-vibrational structure for the two observed excited band structures. Systematics of the one- and two-phonon gamma-vibrational bands in the A similar to 100 Mo series is also discussed.