Lifetime measurements to investigate γ softness and shape coexistence in Mo102

Abstract

Lifetimes of low-spin excited states in $^{102}\mathrm{Mo}$ populated in a $^{100}\mathrm{Mo}(^{18}\mathrm{O},\phantom{\rule{0.16em}{0ex}}^{16}\mathrm{O})^{102}\mathrm{Mo}$ two-neutron transfer reaction were measured using the recoil-distance Doppler-shift technique at the Cologne FN Tandem accelerator. Lifetimes of the ${2}_{1}^{+}$, ${4}_{1}^{+}$, ${6}_{1}^{+}$, ${0}_{2}^{+}$, ${2}_{\ensuremath{\gamma}}^{+}$, ${3}_{\ensuremath{\gamma}}^{+}$ states and one upper limit for the lifetime of the ${4}_{\ensuremath{\gamma}}^{+}$ state were obtained. The energy levels and deduced electromagnetic transition probabilities are compared with those obtained within the mapped interacting boson model framework with microscopic input from Gogny mean-field calculations. With the newly obtained signatures a more detailed insight in the $\ensuremath{\gamma}$ softness and shape coexistence in $^{102}\mathrm{Mo}$ is possible and discussed in the context of the $Z\ensuremath{\approx}40$ and $N\ensuremath{\approx}60$ region. The nucleus of $^{102}\mathrm{Mo}$ follows the $\ensuremath{\gamma}$ soft trend of the Mo isotopes. The properties of the ${0}_{2}^{+}$ state indicate, in contrast with the microscopic predictions, shape coexistence which also occurs in other $N=60$ isotones.