Extremely High Multiplicities in High-Energy Nucleus-Nucleus Collisions

Abstract

Two unusually-high-multiplicity interactions of high-energy heavy nuclei are observed in a balloon-borne emulsion chamber: A Si + Ag Br event (4 TeV/nucleon) and a Ca + C event (100 TeV/nucleon), with 1015 and 760 charged particles, respectively. The multiplicities and rapidity distributions favor the multichain model but not the wounded-nucleon superposition model. The high average ${P}_{T}$ (550-700 MeV/c) and the rapidity fluctuations of the events are not readily understood in terms of any superposition models.