Reaction dynamics in Pb + Pb at the CERN/SPS: From partonic degrees of freedom to freeze-out

Journal Article (Journal Article)

We analyze the reaction dynamics of central Pb+Pb collisions at 160 GeV/nucleon. First we estimate the energy density ∈ pile-up at mid-rapidity and calculate its excitation function: ∈ is decomposed into hadronic and partonic contributions. A detailed analysis of the collision dynamics in the framework of a microscopic transport model shows the importance of partonic degrees of freedom and rescattering of leading (di)quarks in the early phase of the reaction for E ≥ 30 GeV/nucleon. The energy density reaches up to 4 GeV/fm , 95% of which are contained in partonic degrees of freedom. It is shown that cells of hadronic matter, after t ≈ 2R/γυcm, can be viewed as nearly chemically equilibrated. This matter never exceeds energy densities of ∼ 0.4 GeV/fm , i.e. a density above which the notion of separated hadrons loses its meaning. The final reaction stage is analyzed in terms of hadron ratios, freeze-out distributions and a source analysis for final state pions. lab 3 3

Full Text

Duke Authors

Cited Authors

  • Bass, SA; Weber, H; Ernst, C; Bleicher, M; Belkacem, M; Bravina, L; Soff, S; Stöcker, H; Greiner, W; Spieles, C

Published Date

  • January 1, 1999

Published In

Volume / Issue

  • 42 /

Start / End Page

  • 313 - 322

International Standard Serial Number (ISSN)

  • 0146-6410

Digital Object Identifier (DOI)

  • 10.1016/s0146-6410(99)00086-1

Citation Source

  • Scopus