Discrepancy between proton- and alpha-induced cluster knockout reactions onO16

Cross sections for ($p, \mathrm{pd}$) and ($p, \mathrm{pt}$) reactions at 101.3 MeV and ($\alpha , \alpha d$), ($\alpha , \alpha t$), and ($\alpha , \alpha {}_{}{}^3{}_{}{}^{}\mathrm{He}$) reactions at 139.2 MeV have been measured for an ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ target. Distorted wave impulse approximation analyses of the data yield spectroscopic factors for the proton induced reactions which are comparable to shell model estimates. However, the alpha induced reactions yield values up to two orders of magnitude larger. The relationship of these results to similar results for alpha knockout reactions is discussed.