Target mass dependence in relativistic heavy ion collisions

The parameter α for the target mass dependence of the yield of charged particles as a function of pseudorapidity η is investigated for 16O and 32S induced central collisions at 200 A GeV. it is pointed out that α(η) ≤ 0.4 if the linear superposition of nucleon-nucleon interactions is considered. The experimental data α → 1 in the target fragmentation region indicate that the nonlinear effect is important at present incident energy