Observation of a $γ$-band based on two-quasiparticle configuration in $^{70}$Ge

The structure of $^{70}$Ge has been studied through in-beam gamma ray spectroscopy. A new band structure is identified that leads to forking of the ground-state band into two excited bands. Band structures have been investigated using the microscopic triaxial projected shell model approach. The observed forking is demonstrated to result from almost simultaneous band crossing of the two neutron aligned and the γ-band built on this two-quasiparticle configuration with the ground-state band.