One- and two-phonon γ -vibrational bands in neutron-rich Mo107

Abstract

Neutron-rich $^{107}\mathrm{Mo}$ has been reinvestigated by analyzing the large statistics $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ and $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ coincidence data from the spontaneous fission of $^{252}\mathrm{Cf}$ 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 $7/{2}^{\ensuremath{-}}[523]$ 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 $\ensuremath{\gamma}$-vibrational bands built on the $7/{2}^{\ensuremath{-}}[523]$ 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 $\ensuremath{\gamma}$- and $\ensuremath{\gamma}\ensuremath{\gamma}$-vibrational structure for the two observed excited band structures. Systematics of the one- and two-phonon $\ensuremath{\gamma}$-vibrational bands in the $A\ensuremath{\sim}100$ Mo series is also discussed.