CHEMICAL EQUILIBRATION IN HEAVY-ION COLLISIONS

We examine the question of chemical equilibration in heavy-ion collisions by comparing hadron production ratios from the NA35 and WA85 Collaborations with those calculated in an equilibrium thermodynamic model of hadron product. This model includes hadron interactions in a mean field approximation, hadron resonance decays and the effects of finite system size. We find that the mean values obtained from the calculation are in good agreement with experiment, which suggests that the system formed in the heavy-ion collision was in chemical equilibrium. We find that the NA35 and WA85 data are compatible with a freeze-out temperature and baryon number density of 170 MeV and 0.1 fm-3 respectively. In addition, we calculate the statistical fluctuations in the hadron production rates obtained from the model.