Energy dependence of transfer reactions onZn64and two-step processes

Differential cross sections, at proton incident energies between 23.3 and 42.4 MeV, have been measured for the following reactions: ${}_{}{}^{64}{}_{}{}^{}\mathrm{Zn}(p,d){}_{}{}^{63}{}_{}{}^{}\mathrm{Zn}$, ${}_{}{}^{64}{}_{}{}^{}\mathrm{Zn}(p,t){}_{}{}^{62}{}_{}{}^{}\mathrm{Zn}$, and ${}_{}{}^{64}{}_{}{}^{}\mathrm{Zn}(p,\alpha ){}_{}{}^{61}{}_{}{}^{}\mathrm{Cu}$. The data are compared with distorted wave Born approximation calculations. Although good results for the ($p,d$) data are obtained, attempts to fit the experimental energy dependence of the ($p,t$) and ($p,\alpha$) reactions are less successful. The effects of two-step processes have been investigated. It is shown that the ($p,d,t$) successive single-neutron pickup can provide a satisfactory description of the energy dependence of the ($p,t$) cross sections.