Empirical evidence for the importance of coherence effects in theS34(p, α)P31reaction

Differential cross sections have been measured for the ${}_{}{}^{34}{}_{}{}^{}\mathrm{S}(p, \alpha ){}_{}{}^{31}{}_{}{}^{}\mathrm{P}$ reaction at an incident energy of 35.5 MeV. The ($p, \alpha$) relative strengths obtained by distorted wave analyses with a triton cluster form factor are well reproduced by current shell model wave functions. The large differences observed between the ${}_{}{}^{34}{}_{}{}^{}\mathrm{S}(p, \alpha ){}_{}{}^{31}{}_{}{}^{}\mathrm{P}$ and ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}(d, {}_{}{}^3{}_{}{}^{}\mathrm{He}){}_{}{}^{31}{}_{}{}^{}\mathrm{P}$ strengths are due to coherence effects which play an important role in the ($p, \alpha$) reaction amplitude.