StrongL=0 (t,p)Transitions in the Even Isotopes of Ti, Cr, and Fe

Absolute differential cross sections for strong $L=0\mathrm{} \mathrm{}(t,p)\mathrm{}$ transitions on targets of ${}_{}{}^{46,48,50}{}_{}{}^{}\mathrm{Ti}$, ${}_{}{}^{50,52,54}{}_{}{}^{}\mathrm{Cr}$, and ${}_{}{}^{54,56,58}{}_{}{}^{}\mathrm{Fe}$ have been measured. The bombarding energy was 13 MeV and reaction angles of 12.5 and 20° were used. The data are compared with model predictions, with special emphasis on the pairing-vibrational model with isospin. The latter model correctly predicts the dependence on neutron number of the ($t,p$) cross sections but fails, as do all other models, to predict the steady cross-section decrease with increasing $Z$. It is suggested that the latter effect is caused by a slow change in the ground-state correlations.