Evidence for a beta-decaying 1/2- isomer in 71Ni

We report on the investigation of the population mechanism for the 454-keV level in Cu-71. This level was identified for the first time in a recent Coulomb excitation measurement with a radioactive beam of Cu-71. The selective nature of the Coulomb-excitation process as well as nuclear-structure considerations constrain the possible spin values for the newly observed state to I-pi = 1/2(-). A reexamination of the data set obtained in a beta-decay study at the Leuven isotope separator on-line mass separator (LISOL) revealed that this state is also populated in the decay of Ni-71, most probably by direct feeding from a newly identified 1/2(-) beta-decaying isomer having a T-1/2 = 2.3(3) s. In this paper, we investigate the proposed scenario by reanalyzing the beta-gamma and gamma-gamma coincidences obtained in the beta-decay study at LISOL.