Neutron-rich In and Cd isotopes close to the doubly magic ¹³²Sn

Microsecond isomers in the In and Cd isotopes, in the mass range A=123 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 ^123–129In and new measurements of the μs half-lives of the odd-odd ^126–130In are reported. However, the expected 8⁺ isomers in the even-mass Cd isotopes were not observed. The comparisons between the experimental B(M2) 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 ^126,128Cd of ∼10 ns, which could explain the nonobservation of μs isomers. Comparison shows that the calculated levels of ¹³⁰In and ¹²⁹In are in good agreement with the experimental values while some discrepancies occur for the lighter In isotopes. The collectivity of ^126,128Cd is discussed in the framework of the shell model and in comparison with ²⁰⁴Hg.