Direct pickup and knockout processes in inclusive (p, alpha x) reactions from 42 to 300 MeV

Inclusive (p, alpha x) reactions from 42 to 300 MeV are investigated to quantitatively understand the roles of direct pickup and knockout processes. These two processes as well as indirect pickup are incorporated into the intranuclear cascade model. Calculations followed by the evaporation model successfully explain the double-differential cross-section spectra in terms of both shape and magnitude. Direct pickup occupies the low excitation energies of the spectra, and knockout appears between the direct pickup and evaporation regions. The contribution of knockout is negligible below 100 MeV, increases to be comparable with that of direct pickup at 160 MeV, and is dominant above 200 MeV. Indirect pickup shows an important contribution at 300 MeV. The direct pickup and knockout processes show decreasing trends of incident-energy dependence, common to targets ranging from C-12 to Bi-209. However, the decrease of direct pickup is much faster than that for knockout.