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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-22 1:56 |
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Conference: Bucharest University Faculty of Physics 2004 Meeting
Section: Nuclear and Elementary Particles Physics
Title:
Study of the chemical freeze-out in nucleus-nucleus collisions
Authors:
Oana Ristea for the BRAHMS Collaboration
Affiliation:
Faculty of Physics, University of Bucharest
E-mail
Keywords:
Heavy ion ultra-relativistic collisions
Abstract:
Heavy ion collisions at ultra-relativistic energies are studied in order to create and analyze the quark-gluon plasma, which subsequently hadronizes forming the hadrons. Hadron multiplicities and their correlations are observables which can provide information on the
nature, composition and size of the medium from which they are originating.
The hadron yields measured in the energy range from SIS to RHIC are well described by the thermal model assuming chemical equilibrium among produced hadrons at freeze-out. To determine the parameters characterizing chemical freeze-out, we analyze particle yields in terms of
temperature and baryon chemical potential. From the experimental data obtained with BRAHMS experiment, in Au-Au collisions, at 200 AGeV, we obtain the lowest value for the baryon chemical potential and a chemical freeze-out temperature of approximately 170 MeV. The net-baryon density of the central rapidity region has the lowest value, and could explain the baryon chemical potential
behaviour. At the same energy, the baryon chemical potential increase from mid-rapidity to forward rapidities. This behaviour confirms that, the mid-rapidity region is almost a net-baryon free region, and in the region at forward rapidities is still a significant baryon content of the original colliding nuclei.
The energy dependence of chemical parameters is also discussed. As the beam energy is increased, the values for chemical freeze-out temperature are higher and for baryon chemical potential are lower. The trend for chemical potential shows less baryon stopping with increased energy.
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