CERN Accélérateur de science

Microsecond isomers in the In and Cd isotopes, in the mass range 𝐴=123to130, 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
 In 
  and new measurements of the 𝜇⁢s half-lives of the odd-odd  
126–130
 In 
  are reported. However, the expected 8+ isomers in the even-mass Cd isotopes were not observed. The comparisons between the experimental 𝐵⁡(𝑀⁢2) 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
 Cd 
  of ∼10ns, which could explain the nonobservation of 𝜇⁢s isomers. Comparison shows that the calculated levels of  
130
 In 
  and  
129
 In 
  are in good agreement with the experimental values while some discrepancies occur for the lighter In isotopes. The collectivity of  
126,128
 Cd 
  is discussed in the framework of the shell model and in comparison with  
204
 Hg 
 .