Fast-timing lifetime measurements of excited states in Cu-67

The half-lives of the 9/2(+), 13/2(+), and 15/2(+) yrast states in the neutron-rich Cu-67 nucleus were determined by using the in-beam fast-timing technique. The experimentally deduced E3 transition strength for the decay of the 9/2(+) level to the 3/2(-) ground state indicates that the wave function of this level might contain a collective component arising from the coupling of the odd proton p(3/2) with the 3(-) state in Ni-66. Theoretical interpretations of the 9/2(+) state are presented within the particle-vibration weak-coupling scheme involving the unpaired proton and the 3(-) state from Ni-66 and within shell-model calculations with a Ni-56 core using the jj44b residual interaction. The shell model also accounts reasonably well for the other measured electromagnetic transition probabilities.