Forward-angle proton spectra in the continuum from theNi58(p, xp)reaction at 100 MeV

Forward-angle proton energy spectra in the continuum were measured for the reaction ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}(p, xp)$ at 100 MeV with a plastic scintillator used as an active collimator. With this system it was possible to take measurements at angles as small as 8°. It was found that a previously observed broad peak in the continuum, which is suspected to appear as a result of a quasi-free nucleon-nucleon scattering, becomes even more pronounced as the scattering angle decreases. The active collimators were essential in eliminating contributions due to the penetration of collimator edges by elastically scattered protons. At small angles such effects can obscure the quasi-free peak.