Universal Freeze-Out Criterion and Phase-Space Density in Ultrarelativistic Heavy-Ion Collisions

by B. Tomasik (CERN)

Tuesday 27 Aug 2002, 14:30 → 15:00 Europe/Zurich

160/1-009 (CERN)

Recently, the STAR collaboration reported a significant increase in the pion phase space density from SPS to RHIC. Here, we discuss to what extent this finding can be understood as the consequence of a freeze-out criterion for ultrarelativistic heavy-ion collisions, based on pion escape probabilities. To this end, we study the dependence of pion freeze-out on chemical composition, temperature, transverse collective expansion and transverse momentum of the escaping particle. In particular, we find that the dependence of the pion scattering rate on the momentum of the escaping particle can contribute significantly to the transverse momentum slope of transverse HBT radius parameters, and that its temperature dependence favours rather low freeze-out temperatures of 100 MeV at most.

Organiser(s): Yiota Foka, Guy Paic and Urs Wiedemann