23,701 research outputs found
Thermodynamical description of heavy ion collisions
We analyze the thermodynamical state of nuclear matter in transport
descriptions of heavy ion reactions. We determine thermodynamical variables
from an analysis of local momentum space distributions and compare to blast
model parameters from an analysis of fragment energy spectra. These
descriptions are applied to spectator and fireball matter in semi-central and
central Au+Au collisions at SIS-energies, respectively.Comment: 4 pages, 2 postscript-figures, to be published in the proceedings of
Bologna2000: Structure of the Nucleus at the Dawn of the Century, Bologna,
Italy, 29 May - 3 Jun 200
Relativistic heavy ion collisions with realistic non-equilibrium mean fields
We study the influence of non-equilibrium phase space effects on the dynamics
of heavy ion reactions within the relativistic BUU approach. We use realistic
Dirac-Brueckner-Hartree-Fock (DBHF) mean fields determined for
two-Fermi-ellipsoid configurations, i.e. for colliding nuclear matter, in a
local phase space configuration approximation (LCA). We compare to DBHF mean
fields in the local density approximation (LDA) and to the non-linear Walecka
model. The results are further compared to flow data of the reaction on
at 400 MeV per nucleon measured by the FOPI collaboration. We find that
the DBHF fields reproduce the experiment if the configuration dependence is
taken into account. This has also implications on the determination of the
equation of state from heavy ion collisions.Comment: Physics Letters B in press; 10 pages, Postscript file replaced by
Latex file and 3 Postscript figure
Testing Dirac-Brueckner models in collective flow of heavy-ion collisions
We investigate differential in-plane and out-of-plane flow observables in
heavy ion reactions at intermediate energies from AGeV within the
framework of relativistic BUU transport calculations. The mean field is based
on microscopic Dirac-Brueckner-Hartree-Fock (DBHF) calculations. We apply two
different sets of DBHF predictions, those of ter Haar and Malfliet and more
recent ones from the T\"ubingen group, which are similar in general but differ
in details. The latter DBHF calculations exclude spurious contributions from
the negative energy sector to the mean field which results in a slightly softer
equation of state and a less repulsive momentum dependence of the
nucleon-nucleus potential at high densities and high momenta. For the
application to heavy ion collisions in both cases non-equilibrium features of
the phase space are taken into account on the level of the effective
interaction. The systematic comparison to experimental data favours the less
repulsive and softer model. Relative to non-relativistic approaches one obtains
larger values of the effective nucleon mass. This produces a sufficient amount
of repulsion to describe the differential flow data reasonably well.Comment: 14 pages Revtex, 19 figures, discussion extended and two figures
added, accepted for publication in EPJ
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