Space-time picture of high-energy heavy-ion collisions and scaling properties of proton spectra

Abstract

A comparative analysis of predictions of three typical models of relativistic nucleus-nucleus collisions is performed. It includes the model of partial transparency, the hydrodynamical model and the intranuclear cascade model. The results of proton and pion spectra calculations are compared with the experimental data available at incident energies of 0.8, 2.1 and 3.6 GeV nucleon . The effects of deviation from thermodynamical equilibrium due to mutual transparency of projectile and target nuclei are studied. The importance of the transition layer arising on the boundary of the overlapping parts of interacting nuclei has been demonstrated. The emission from this layer gives the main contribution to inclusive proton spectra in the target fragmentation region. In this region all the three models are in good agreement with experiment and, in particular, reproduce the scaling properties of proton inclusive cross sections satisfactorily. Considerable difference in the models' predictions takes place in the central rapidity region, especially in central collisions of identical nuclei. Experiments are suggested to study the mechanisms of the transition layer formation and the nature of scaling behaviour of proton spectra.