The $\gamma$-ray decay of isomeric states in the even-even nucleus ${}^{128}\mathrm{Cd}$ has been observed. The nucleus of interest was produced both by the fragmentation of ${}^{136}\mathrm{Xe}$ and the fission of ${}^{238}\mathrm{U}$ primary beams. The level scheme was unambiguously constructed based on $\gamma \gamma$ coincidence relations in conjunction with detailed lifetime analysis employed for the first time on this nucleus. Large-scale shell-model calculations, without consideration of excitations across the $N=82$ shell closure, were performed and provide a consistent description of the experimental level scheme. The structure of the isomeric states and their decays exhibit coexistence of proton, neutron, and strongly mixed configurations due to $\pi \nu$ interaction in overlapping orbitals for both proton and neutron holes.

• Received 24 September 2008

DOI:https://doi.org/10.1103/PhysRevC.79.011301