We report on the investigation of the population mechanism for the 454-keV level in ${}^{71}\mathrm{Cu}$. This level was identified for the first time in a recent Coulomb excitation measurement with a radioactive beam of ${}^{71}\mathrm{Cu}$. 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 ${}^{71}\mathrm{Ni}$, 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 $\beta \text{−}\gamma$ and $\gamma \text{−}\gamma$ coincidences obtained in the $\beta$-decay study at LISOL.

• Received 22 January 2009

DOI:https://doi.org/10.1103/PhysRevC.79.044325