Equilibrium and non-equilibrium effects in nucleus - Nucleus collisions
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.
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- Nuclear & Particles Physics
- 51 Physical sciences
- 49 Mathematical sciences
- 0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics
- 0201 Astronomical and Space Sciences
- 0105 Mathematical Physics
Citation
Published In
DOI
ISSN
Publication Date
Volume
Issue
Start / End Page
Related Subject Headings
- Nuclear & Particles Physics
- 51 Physical sciences
- 49 Mathematical sciences
- 0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics
- 0201 Astronomical and Space Sciences
- 0105 Mathematical Physics