Observation of Hole States at High Excitation in (p, t) Reactions

A peak about 2 MeV wide is observed at $E_x\sim 8-9$ MeV in six even-even tin isotopes and at lower excitation in ${}_{}{}^{104}{}_{}{}^{}\mathrm{Cd}$ and ${}_{}{}^{102}{}_{}{}^{}\mathrm{Pd}$ in the ($p, t$) reaction at 42 and 45 MeV. The excitation energy of the peak and its width increase with increasing neutron number. The peak may arise from two-neutron pickup from the lower-lying $\mathrm{gpf}$ shell. Distorted-wave Born-approximation calculations agree well with the angular distributions and indicate that 45% of the total strength is observed experimentally.