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Published: 1975

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The effect of free-particle collisions in simple ''knockout'' reactions of the form (a, aN) and in more complex nuclear reactions of the form (a, X) was investigated by using protons and pions. Cross sections for the $sup 48$Ti(p,2p)47Sc and the 74Ge(p,2p)73Ga reactions were measured from 0.3 to 4.6 GeV incident energy. The results indicate a rise in (p,2p) cross section for each reaction of about (25 +- 3) percent between the energies 0.3 and 1.0 GeV, and are correlated to a large increase in the total free-particle pp scattering cross sections over the same energy region. Results are compared to previous (p,2p) excitation functions in the GeV energy region and to (p,2p) cross section calculations based on a Monte Carlo intranuclear cascade-evaporation model. Cross section measurements for ([pi]/sup +-/, [pi]N) and other more complex pion-induced spallation reactions were measured for the light target nuclei 14N, 16O, and 19F from 45 to 550 MeV incident pion energy. These measurements indicate a broad peak in the excitation functions for both ([pi], [pi]N) and ([pi], X) reactions near 180 MeV incident energy. This corresponds to the large resonances observed in the free-particle [pi]p and [pi]−p cross sections at the same energy. Striking differences in ([pi], [pi]N) cross section magnitudes are observed among the light nuclei targets. The experimental cross section ratio sigma([pi]−, [pi]−n)/ sigma($pi$$sup +$, $pi$N) at 180 MeV is 1.7 +- 0.2 for all three targets. The experimental results are compared to previous pion and analogous proton-induced reactions, to Monte Carlo intranuclear cascade-evaporation calculations, and to a semi-classical nucleon charge exchange model. (108 references) (auth).