Collision centrality dependencies of charged pion production in 12C+ 181 Ta collisions at 4.2 A GeV/c

Abstract

The collision centrality dependencies of the average kinematical characteristics of the negative and positive pions, produced in [Formula: see text] collisions at [Formula: see text], were investigated. The ratio [Formula: see text] proved to be [Formula: see text], [Formula: see text] and [Formula: see text] in the peripheral, semicentral, and central [Formula: see text] collision events, respectively, decreasing noticeably with increasing collision centrality. The suppression (decrease) of the ratio [Formula: see text] was observed in the semicentral and central [Formula: see text] collisions as compared to the ratio [Formula: see text], estimated using the simple model for [Formula: see text] collision system. The ratio [Formula: see text] estimated using the simple model agreed well with the corresponding ratio [Formula: see text], estimated for [Formula: see text] collisions at [Formula: see text] based on the Wounded Nucleon Model (WNM). Comparison of the emission angle as well as momentum distributions of the charged pions in the peripheral and central [Formula: see text] collisions revealed the significant decrease of the fraction of the relatively fast charged pions (with smaller emission angles) and increase of the fraction of the relatively slow charged pions (with larger emission angles) with an increase in collision centrality. The results of the present analysis can be useful for analysis of the centrality dependence of the charged pion production in heavy ion collisions at high energies.