Shape coexistence in 76Se within the neutron–proton interacting boson model

Abstract We have investigated the low-lying energy spectrum and electromagnetic transition strengths in even–even 76 Se using the proton–neutron interacting boson model (IBM-2). The theoretical calculation for the energy levels and E 2 and M 1 transition strengths is in good agreement with the experimental data. Specifically, the excitation energy and E 2 transition of 0 2 + state, which is intimately associated with shape coexistence, can be accurately reproduced. The analysis on low-lying states and the key structure indicators R 1 , R 2 , R 3 and R 4 and M 1 transitions indicates that there is a coexistence between spherical shape and γ -soft shape in 76 Se.