Central heavy ion collisions with emulsion at 4.2 GeV/c per incident nucleon

The investigated data represent the most central collisions which had ever been studied yet. The analysis of the experimental data shows agreement with the limiting fragmentation hypothesis. The multiple production of particles in central collisions is consistent with the assumption of superposition of nucleon-nucleon collisions. There is no strong correlation between the produced pions in this class of interactions. The angular distributions of target fragmentation particles do not show statistically significant peak which would have been attributed to a collective ''shock wave'' phenomenon. The longitudinal velocity of the emitting system, found from black tracks analysis, is low and typically equals 0.014+-0.002