Evolution of collectivity and shape transition in 66Zn

Excited states in Zn-66 were investigated through the in-beam gamma-ray spectroscopic techniques using the Cr-52(O-18, 2p2n) fusion-evaporation reaction at a beam energy of 72.5 MeV. The gamma-rays emitted by the deexciting nuclei were recorded in coincidence mode using the 14 Compton suppressed Ge clover detectors of the Indian National Gamma Array. With 14 new transitions being identified, the level scheme of Zn-66 has been extended up to the excitation energy approximate to 12.3 MeV and spin approximate to 17 (h) over bar. A rotational band, associated with the two quasineutrons from the 1g(9/2 )orbital, has been found to exhibit a band crossing with the ground-state band at a spin of 6 (h) over bar. The evolution of the collectivity and shape transition in this nucleus have been discussed in the framework of the total Routhian surface calculations and in comparison with the neighboring Ge-68,Ge-70 nuclei.