NA49 Results on Single Particle and Correlation Measurements in Central PB+PB Collisions

NA49 Results on Single Particle and Correlation Measurements in Central PB+PB Collisions
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Total Pages: 14
Release: 1998
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Single-particle spectra and two-particle correlation functions measured by the NA49 collaboration in central Pb+Pb collisions at 158 GeV/nucleon are presented. These measurements are used to study the kinetic and chemical freeze-out conditions in heavy ion collisions. We conclude that large baryon stopping, high baryon density and strong transverse radial flow are achieved in central Pb+Pb collisions at the SPS.

Two-Particle Correlations at 40, 80, and 158 AGeV Pb-Au Collisions

Two-Particle Correlations at 40, 80, and 158 AGeV Pb-Au Collisions
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Total Pages:
Release: 2002
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In this thesis, a centrality dependent study of tow-particle momentum correlations of like-sign pions (HBT interferometry) from Pb-Au collisions at beam energies of 40, 80 and 158 AGeV is presented. The three-dimensional correlation function C_2, depending on the relative momentum components of the particle pair, was parameterized using a three-dimensional Gaussian, modified to consider the final state Coulomb repulsion. The parameterization was done in the Cartesian out-side-long system as proposed by G. Bertsch and S. Pratt. A differential analysis of the HBT radius parameters as a function of the mean transverse pair momentum k_perp allowed to determine transverse geometrical source sizes of about 5.5 fm to 7 fm, increasing with energy and centrality. The mean transverse flow velocity v_perp was found to be of the order 0.5--0.6 c. For the freeze-out time tau_f values between 6 and 8 fm/c were obtained with a duration of particle emission compatible with zero. The beam energy dependence of the HBT radii provide evidence for a universal pion freeze-out condition. The analyzed data have been recorded with the CERES spectrometer at the Super Proton Synchrotron (SPS) accelerator at CERN.