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Universal Pion Freeze-out in Heavy-Ion Collisions

CERES Collaboration
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Abstract

Based on an evaluation of data on pion interferometry and on particle yields at mid-rapidity, we propose a universal condition for thermal freeze-out of pions in heavy-ion collisions. We show that freeze-out occurs when the mean free path of pions lambda_f reaches a value of about 1 fm, which is much smaller than the spatial extent of the system at freeze-out. This critical mean free path is independent of the centrality of the collision and beam energy from AGS to RHIC.

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CERES Collaboration. 2002-10-16. Universal Pion Freeze-out in Heavy-Ion Collisions. https://doi.org/10.1103/physrevlett.90.022301

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