Modelling correlations in heavy ion collisions

Modelling correlations in heavy ion collisions is reviewed from model independent characterization of the two-particle correlations to Buda-Lund hydro model fits to correlations and spectra in Au + Au collisions at sqrt{s}=130 AGeV at RHIC.Comment: 6 pages, 2 figures, talk given at XXXI International Symposium on Multiparticle Dynamics, Sept 1-7, 2001, Datong China. See http://202.114.35.18

The reconstructed final state of Au + Au collisions from PHENIX and STAR data at sqrt{s}=130 AGeV - indication for quark deconfinement at RHIC

The final state of Au + Au collisions at sqrt{s}=130 AGeV at RHIC has been reconstructed within the framework of the Buda-Lund hydrodynamical model, by performing a simultaneous fit to final data on two-particle Bose-Einstein correlations of the STAR and PHENIX Collaborations, and final identified single particle spectra as measured by the PHENIX Collaboration. The results indicate a strongly three-dimensional expansion with a four-velocity field that is almost a spherically symmetric Hubble flow. We find large transverse geometrical source sizes, R_G = 9.8 +- 1.2 fm, a relatively short mean freeze-out time of tau0 = 6.1 +- 0.3 fm/c and a short duration of particle emission, Delta_tau = 0.02 +- 1.5 fm/c. Most strikingly, we find an indication for a hot central part or the hydrodynamically evolving core, characterized by a central temperature of T0 = 202 +- 13 MeV, that is close to (or even above) the deconfinement temperature of the quark-hadron phase transition. The best fit indicates a cold surface temperature of T_s = 110 +- 16 MeV. When the possibility of the hot center is excluded, the confidence level of the fit decreases from 28.9 % to 1.2 %. Predictions are made for the rapidity dependence of the slope parameters, for the transverse mass dependence of the rapidity-width of the single-particle spectra, and for the transverse velocity dependence of the non-indentical particle correlations.Comment: 18 pages, 3 eps figures, based on the talk of A. Ster at the Budapest 02 workshop on Quark and Hadron Dynamics, budapest1.st

An indication for deconfinement in Au+Au collisions at RHIC

We present simultaneous, quality fits to final BRAHMS, PHENIX, PHOBOS and STAR data on particle spectra and two-particle Bose-Einstein or HBT correlations as measured in Au+Au collisions at $\sqrt{s_{NN}} = 130$ GeV. Using the Buda-Lund hydro model, the best fit is achieved when the most central 1/8th of the particle emitting volume is superheated to $T > T_c =170$ MeV. In contrast, we find no indication for such a hot central region in a similar analysis of Pb+Pb data at CERN SPS.Comment: 6 pages, 2 figures, 1 table, presented by A. Ster at the XXXIIIth International Symposium on Multiparticle Dynamics, Cracow, Poland, Sept. 200

Understanding the rapidity dependence of the elliptic flow and the HBT radii at RHIC

The pseudo-rapidity dependence of the elliptic flow at various excitation energies measured by the PHOBOS Collaboration in Au+Au collisions at RHIC is one of the surprising results that has not been explained before in terms of hydrodynamical models. Here we show that these data are in agreement with theoretical predictions and satisfy the universal scaling relation predicted by the Buda-Lund hydrodynamical model, based on exact solutions of perfect fluid hydrodynamics. We also show a theoretical prediction on the rapidity and transverse momentum scaling of the HBT radii measured in heavy ion collisions, based on the Buda-Lund model.Comment: 6 pages, 2 figures, proceedings contribution for M. Csanad's talk at the Workshop on Particle Correlations and Femtoscopy 2005, Kromeri

Linac 2 Performance optimization

In recent years the CERN proton linear accelerator Linac 2 operated with an approximately 90% particle transmission efficiency. The losses concerned mainly the first accelerating tank of the equipment. An intelligent procedure that optimizes the operational control settings has been developed in order to eliminate some of these losses and increase the transmission rate. Both on-line and simulation versions of the program are available. This report describes the method of optimization, presents the measurement and simulation results along with the achieved ~3% improvement, points out the limitations which cause the remaining and currently unavoidable particle loss. In the appendix a user guide of the program is provided

A hint at quark deconfinement in 200 GeV Au+Au data at RHIC

We give the emission function of the axially symmetric Buda-Lund hydro model and present its simultaneous, high quality fits to identified particle spectra, two-particle Bose-Einstein or HBT correlations and charged particle pseudorapidity distributions as measured by BRAHMS and PHENIX in 0-30 % central, \sqrt{s_{\NN}} = 200 GeV Au+Au collisions at RHIC. The best fit is achieved when the most central region of the particle emitting volume is superheated to $T_0 = 200 \pm 9$ MeV $\ge T_c =172 \pm 3$ MeV, a preliminary, 3 $\sigma$ effect.Comment: 10 pages, 3 figures, talk of A. Ster at the 2nd Warsaw Meeting on Correlations and Resonances in HIC, see http://hirg.if.pw.edu.pl/en/meeting/oct2003/talks/csorgo/Ster.pp

From Quark Gluon Plasma to a Perfect Fluid of Quarks and Beyond

With high energy heavy ion collisions one tries to create a new forms of matter that is similar to the one present at the birth of our Universe. Recent development on flow pattern, initial energy-density and freeze-out temperature shows that most likely this new form of matter is in a deconfined state, has colored degrees of freedom and is more fluid-like than gas-like. In present paper we calculate estimations on the physical properties of this new-old matter.Comment: 10 pages, 5 figures, to appear in the proceedings of the 44th International School of Subnuclear Physics, Erice, Sicily, 29 August - 7 September 200