Equilibrium and non-equilibrium effects in nucleus - Nucleus collisions


Journal Article

Local thermal and chemical equilibration is studied for central A + A collisions at 10.7-160 AGeV in the Ultrarelativistic Quantum Molecular Dynamics model (UrQMD). The UrQMD mode exhibits strong deviations from local equilibrium at the high density hadron-string phase formed during the early stage of the collision. Equilibration of the hadron-resonance matter is established in the central cäl of volume V = 125 fmat later stages, t > 10 fm/c, of the resulting quasi-isentropic expansion. The thermodynamical functions in the cell and their time evolution are presented. Deviations of the UrQMD quasi-equilibrium state from the statistical mechanics equilibrium are found. They increase with energy per baryon and lead to a strong enhancement of the pion number density as compared to statistical mechanics estimates at SPS energies. ©1999 Published by Elsevier Science B.V. All rights reserved.

Full Text

Duke Authors

Cited Authors

  • Bravina, LV; Gorenstein, MI; Zabrodin, EE; Bass, SA; Belkacem, M; Bleicher, M; Brandstetter, M; Hofmann, M; Soff, S; Spieles, C; Weber, H; Stöckerand, H; Greiner, W

Published Date

  • January 1, 1999

Published In

Volume / Issue

  • 459 / 4

Start / End Page

  • 660 - 666

International Standard Serial Number (ISSN)

  • 0370-2693

Digital Object Identifier (DOI)

  • 10.1016/S0370-2693(99)00692-9

Citation Source

  • Scopus