Light fragment emission as studied by the (p,pHe) reactions on Be and Ag with 300 MeV protons

Inclusive and exclusive differential cross sections have been measured for the ({ital p},{ital p}He) reaction on Be and Ag with 300 MeV protons. Detectors in coplanar geometry were used to measure singles spectra and coincidence spectra between protons and He isotopes. The particle spectra are surprisingly similar between the inclusive and exclusive measurements as well as between the two widely different targets. The proton differential mean multiplicities associated with He emission show significant structure as a function of He emission angles except for the case of low energy emission from Ag. An analysis of the data in terms of rapidity and relativistically invariant cross section is in general agreement with the notion of isotropic emission from a moving source for the He isotopes from both targets. Only in extreme kinematic regions, where events were selected in which momentum in excess of 300 MeV/{ital c} was transferred to the target system, did the contours become nonspherical. The mass of the emitting source is shown to be small. The results are consistent with the concept of deexcitation of a small excited source by effective binary breakup leading to fragment emission.