Microsecond isomers in the In and Cd isotopes, in the mass range $A=123\text{to}130$, were investigated at the ILL reactor, Grenoble, using the LOHENGRIN mass spectrometer, through thermal-neutron induced fission reactions of Pu targets. The level schemes of the odd-mass ${}^{123–129}\mathrm{In}$ and new measurements of the $\mu \mathrm{s}$ half-lives of the odd-odd ${}^{126–130}\mathrm{In}$ are reported. However, the expected $8^{+}$ isomers in the even-mass Cd isotopes were not observed. The comparisons between the experimental $B\left(M2\right)$ strengths for In and Sn isotopes are discussed. A shell-model study of the heaviest In and Cd nuclei was performed using a realistic interaction derived from the CD-Bonn nucleon-nucleon potential. The calculation predicts values of the half-lives of the first $8^{+}$ states in ${}^{126,128}\mathrm{Cd}$ of $\sim 10\mathrm{ns}$, which could explain the nonobservation of $\mu \mathrm{s}$ isomers. Comparison shows that the calculated levels of ${}^{130}\mathrm{In}$ and ${}^{129}\mathrm{In}$ are in good agreement with the experimental values while some discrepancies occur for the lighter In isotopes. The collectivity of ${}^{126,128}\mathrm{Cd}$ is discussed in the framework of the shell model and in comparison with ${}^{204}\mathrm{Hg}$.

• Received 29 July 2004

DOI:https://doi.org/10.1103/PhysRevC.70.054318