Search for particle-vibration coupling in Cu-65

The lifetime of the 9/2+state of65Cu, at 2534 keV, has been measured by fast timing techniques, in order to establish wether such state arises from a weak coupling between a p3/2proton and the 3-octupole vibration at 3.56 MeV in the64Ni core. The65Cu nucleus was populated by the reaction7Li +64Ni at 32 MeV, at the Horia Hulubei National Institute of Physics and Nuclear Engineering (NIPNE) in Bucharest, and its γ-decay was detected by the ROSPHERE array. The measured lifetime coresponds to a B(E3) reduced transition probability to the ground state equal to 8.89 W.u., in agreement with theoretical predictions in the weak coupling limit.