Identification of levels above 6- isomeric state in 66Cu

Excited states in odd-odd 66Cu were investigated in a reaction between a 136MeV 30Si beam and a 65Cu target with the Indian National Gamma Array. Six new transitions have been identified including four transitions feeding the 600ns \(6^{-}\) isomeric state from an investigation of prompt-prompt and prompt-delayed coincidence events. The results of the present work have extended the level structure of this nucleus up to \(I^{\pi}=(9^{-})\). In addition, new information on the set of \( \pi p_{3/2} \nu g_{9/2}\) multiplets in this nucleus have been added. Shell model calculations were performed within the \( fpg_{9/2}\) and \( f_{5/2}pg_{9/2}\) model spaces. The results of shell model calculations using the \( fpg_{9/2}\) model space have been observed to be in better agreement with experimental excitation energies up to the highest spin observed. The results of the present work highlight the necessity of \( f_{7/2}\) proton holes to describe the positive as well as negative parity states in 66Cu.