Shape coexistence close to $N=50$ in the neutron-rich isotope $^{80}$Ge investigated by IBM-2

Abstract

The properties of the low-lying states, especially the relevant shape coexistence in 80 Ge close to one of most neutron-rich doubly magic nuclei at N = 50 and Z = 28 have been investigated within the framework of the proton-neutron interacting model (IBM-2). Based on the fact that the relative energy of the d neutron boson is different from proton bosons', the calculated energy levels of low-lying states, E2 transition strengths can reproduce the experimental data very well.Particularly, the first excited state 0 + 2 is reproduced quite nicely, which is intimately related with the shape coexistence phenomenon. And the ρ 2 (E0, 0 + 2 → 0 + 1 ) transition strength has been predicted.The experimental data and theoretical results indicate that both collective spherical and γ-soft vibration structures coexist in 80 Ge.