HOW MANY NUCLEONS ARE REQUIRED FOR NUCLEAR PION ABSORPTION

The inclusive spectra of protons from the interactions of positive and negative pions with different nuclei at incident-pion energies from 1 00 MeV to 1 GeV are analyzed in the cascade-exciton model of nuclear r eactions. The contributions of various pion-absorption mechanisms and the relative role of various mechanisms of particle production in thes e reactions are discussed. The results obtained here, as well as in ou r previous analysis of a large variety of experimental data on pion-nu cleus reactions at bombarding energies in the range 0 - 3 GeV, confirm the conclusion that pion absorption proceeds predominantly via the tw o-nucleon mechanism. It is shown that the data on pion-induced inclusi ve proton production, which are intensively discussed in the literatur e, can be satisfactorily described on the basis of the two-nucleon abs orption mechanism alone, provided that the initial- and final-state in teractions are taken into account.