(p, t) Ground-StateL=0Transitions in the Even Isotopes of Sn and Cd at 40 MeV,N=62 to 74

The ($p, t$) reaction has been used to investigate the ground-state $L=0\mathrm{}$ transitions in the seven even Sn isotopes and four even Cd isotopes with the University of Minnesota Linear Accelerator 40-MeV proton beam. Angular distributions have been taken in the range 7° to 25° in most cases, and the integrated cross sections used for comparison with the theory. The isotopes of Sn have a closed $Z=50\mathrm{}$ proton shell and should be rather well described in terms of the neutrons outside of the $N=50\mathrm{}$ shell. The detailed description of the neutron configurations is available from theoretical work and one-neutron transfer reactions. The agreement between pairing spectroscopic factors and the experimental cross sections is not good. It is clear that a distorted-wave Born-approximation analysis of the data is necessary, as well as, perhaps, a better understanding of the nuclear structure of the Sn isotopes. The Cd data show that an open proton shell decreases the number of $J=0\mathrm{}$ coupled neutron pairs in the ground state.