Particle production at high energy. II. Accumulative impact and clustering in relativistic heavy-ion collisions

Transverse energy dependence dET/dη of O+Ag, S+Ag, and S+W collisions at 200 GeV/c are analyzed in a parameter-free phenomenological model of cascade and clustering based on p+p and p+Ag collisions. The model uses an event generator which explicitly displays the impact parameter dependence of the colliding hadrons and incorporates basic features of multiparticle production in p+p collisions. p+Ag data at 200 GeV/c are first analyzed with special attention to the time ordering of the cascading many-body processes using the space-time geometry and the impact parameter dependence of the colliding hadrons. We introduce a relaxation time parameter τ, the size of a time interval of the overlapping regions of space-time in the center-of-momentum frame of the colliding hadrons. Within a τ interval of relaxation, impacts of all collisions are accumulative. Only after this time has passed are pions allowed to be emitted from excited nuclear matter according to a set of rules for cascade. A value of τ∼0.1 fm/c used for p+Ag data leads to a description of the gross features of the transverse energy dependence dET/dη of O+Ag and S+Ag data of WA80 and S+W data in the forward region of HELIOS. copyright 1997 The American Physical Society