Evidence for shape coexistence in $^{98}$Mo
Abstract
A γγ angular-correlation experiment has been performed to investigate the low-energy states of the nucleus 98Mo. The new data, including spin assignments, multipole mixing ratios, and lifetimes reveal evidence for shape coexistence and mixing in 98Mo, arising from a proton intruder configuration. This result is reproduced by a theoretical calculation within the proton-neutron interacting boson model with configuration mixing, based on microscopic energy density functional theory. The microscopic calculation indicates the importance of the proton particle-hole excitation across the Z = 40 subshell closure and the subsequent mixing between spherical vibrational and the γ -soft equilibrium shapes in 98Mo.