9,977 research outputs found
Transverse-Mass Effective Temperature in Heavy-Ion Collisions from AGS to SPS
Transverse-mass spectra in Au+Au and Pb+Pb collisions in incident energy
range from 2A to 160A GeV are analyzed within the model of 3-fluid dynamics. It
is shown that dynamical description of freeze-out, accepted in this model,
naturally explains the incident energy behavior of inverse-slope parameters of
these spectra observed in experiment. Simultaneous reproduction of the
inverse-slopes of all considered particles (protons, pions and kaons) suggests
that these particles belong to the same hydrodynamic flow at the instant of
their freeze-out.Comment: 4 pages, 3 figure
Estimation of the Shear Viscosity from 3FD Simulations of Au+Au Collisions at 3.3--39 GeV
An effective shear viscosity in central Au+Au collisions is estimated in the
range of incident energies 3.3 GeV 39 GeV. The
simulations are performed within a three-fluid model employing three different
equations of state with and without the deconfinement transition. In order to
estimate this effective viscosity, we consider the entropy produced in the 3FD
simulations as if it is generated within the conventional one-fluid viscous
hydrodynamics. It is found that the effective viscosity within different
considered scenarios is very similar at the expansion stage of the collision:
as a function of temperature () the viscosity-to-entropy ratio behaves as
; as a function of net-baryon density (), , i.e. it is mainly determined by the density dependence of the entropy
density. The above dependencies take place along the dynamical trajectories of
Au+Au collisions. At the final stages of the expansion the values are
ranged from 0.05 at highest considered energies to 0.5 at the
lowest ones.Comment: 4 pages, 3 figures, to be published in Eur. Phys. Journ.
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