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Charged particle multiplicities from high-multiplicity interactions of 158 GeV/nucleon Pb ions with Pb target nuclei have been measured using high-resolution nuclear emulsion chambers with sensitivity from the peak of the pseudorapidity distribution forward to [Formula Presented] The characteristics of these interactions have been compared to those of central interactions of 200 GeV/nucleon proton, O, and S beams on silver or bromine targets and to results from simulations using the FRITIOF 7.02 and VENUS 4.12 Monte Carlo event generators. Multiplicities scale with the number of wounded nucleons, although the multiplicities for Pb+Pb interactions in the central region are significantly lower than predicted by either Monte Carlo model. We examine the shape of the pseudorapidity distribution and its dependence on centrality in detail, because in this symmetric system the participant projectile target masses are independent of centrality, so any dependence of the shape on centrality must therefore be a dynamical effect. No dependence of the produced particle pseudorapidity distribution on multiplicity or centrality is seen. VENUS, the only one of the two models which attempts to incorporate reinteraction phenomena, predicts a narrowing of the pseudorapidity distributions for the highest multiplicity events, which we do not observe. In general, FRITIOF produces better fits to the all-charged-particle (primarily pion) data than does VENUS. © 2000 The American Physical Society.

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Physical Review C - Nuclear Physics

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