1,686 research outputs found
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 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 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 MeV MeV, a preliminary,
3 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
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