Evidence for core-coupled states inY87from aY89(p,t)Y87andSr88(p,t)Sr86comparison

The ${}_{}{}^{89}{}_{}{}^{}\mathrm{Y}(p,t){}_{}{}^{87}{}_{}{}^{}\mathrm{Y}$ and ${}_{}{}^{88}{}_{}{}^{}\mathrm{Sr}\mathrm{}(p,t)\mathrm{}{}_{}{}^{86}{}_{}{}^{}\mathrm{Sr}$ reactions were studied at 42 MeV proton energy, using a quadrupole-dipole-dipole-dipole spectrograph. Comparison of excitation energies, ($p,t$) cross-section strengths, and angular distribution shapes indicates that basic features of the core-coupling model apply to these nuclei. However, mixing of single-particle states with the core-coupled states is evident. The ($p,t$) cross-section strength summed over the ${}_{}{}^{87}{}_{}{}^{}\mathrm{Y}$ multiplet is found with few exceptions to be nearly a constant multiple of the ($p,t$) strength of the associated ${}_{}{}^{86}{}_{}{}^{}\mathrm{Sr}$ state.