Energy and collision centrality dependencies of the average characteristics of the charged pions in p12C collisions at 4.2 and 9.9 GeV/<i>c</i>
Abstract
Various characteristics of the negative and positive pions produced in [Formula: see text]C collisions at an incident proton momentum of 4.2 and 9.9[Formula: see text]GeV/c have been investigated depending on the degree of collision centrality. The average number of negative and positive pions and the average values of partial inelasticity coefficients increase with an increase in the number of protons from the fragmentation region of the target nucleus participating in the interaction. The shape of the transverse momentum distribution of the negative pions and the average values of their transverse momentum do not depend on the degree of centrality of [Formula: see text]C collisions. The average values of the multiplicity and kinematical characteristics of the positive pions turned out to be somewhat larger than those for negative pions, which is associated with the contribution of the inelastic charge exchange conversion of the initial proton to a neutron and [Formula: see text] meson. Differences in the characteristics of the negative and positive pions at different energies and various collision centralities are interpreted as being due to the centrality selection criterion, based on the number of participant protons and the conservation laws of energy, baryon number and electric charge in [Formula: see text]C collisions. The experimental data have been systematically compared with the results of calculations using the modified FRITIOF model.