Central12C-emulsion collisions at 4.5A GeV/c

Abstract

Central collisions of12C with emulsion nuclei at 4.5A GeV/c have been investigated. Central collisions are defined as events withNh≥28 and having no observable projectile fragments emitted within 3° of the beam direction. The probability of central collisions is found to be 11.68% and it increases with the mass of the projectile. The multiplicity distribution of shower particles is a Poisson one which indicates the absence of correlations between the produced pions. F/B for black and grey particles are 1.40±0.04 and 2.95±0.10, respectively, and no peaks are observed in the angular distribution of target fragments which could be attributed to the shock-wave phenomenon. Evidence of strong correlations between the produced particles has been obtained. This indicates that the particle production in nucleus-nucleus collisions takes place via cluster production. However, the absence of higher-order correlations rules out the possibility of the production of quark-gluon plasma, in these collisions. Furthermore, no evidence is found the production of fireball-type heavy clusters predicted by Adamovich et al.