Equilibrium and non-equilibrium effects in nucleus-nucleus collisions

被引:6
作者
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
机构
[1] Goethe Univ Frankfurt, Inst Theoret Phys, D-6000 Frankfurt, Germany
[2] Moscow MV Lomonosov State Univ, Inst Nucl Phys, Moscow 119899, Russia
[3] Bogolyubov Inst Theoret Phys, Kiev, Ukraine
[4] Univ Tubingen, Inst Theoret Phys, D-7400 Tubingen, Germany
[5] Duke Univ, Dept Phys, Durham, NC 27706 USA
[6] Gesell Schwerionenforsch mbH, D-6100 Darmstadt, Germany
[7] Univ Calif Berkeley, Lawrence Berkeley Lab, Div Nucl Sci, Berkeley, CA 94720 USA
关键词
heavy ion collisions; QMD model; local thermodynamical equilibrium; equation of state; non-equilibrium effects;
D O I
10.1016/S0370-2693(99)00692-9
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
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 model 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 cell of volume V = 125 fm(3) at later stages, t greater than or equal to 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. (C) 1999 Published by Elsevier Science B.V. All rights reserved.
引用
收藏
页码:660 / 666
页数:7
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