Probing collectivity in Zn isotopes with one particle or hole outside the N =40 subshell closure

The nuclear structure of the odd-mass ⁶⁹Zn and ⁷¹Zn isotopes, with one hole or one particle outside the N =40 subshell closure, has been investigated by measuring the lifetime of excited states using the recoil distance Doppler-shift method. The nuclei of interest were produced in a deep-inelastic reaction in inverse kinematics with a ²³⁸U beam impinging on a ⁷⁰Zn target. Single-particle and collective states were found to coexist at low energy in ⁶⁹Zn and ⁷¹Zn.