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

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 E2 and M1 transition strengths is in good agreement with the experimental data.Specifically,the excitation energy and E2 transition of 0_(2)^(+) state,which is intimately associated with shape coexistence,can be accurately reproduced.The analysis on lowlying states and the key structure indicators R_(1),R_(2),R_(3) and R_(4) and M1 transitions indicates that there is a coexistence between spherical shape and γ-soft shape in ^(76)Se.