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CERN Heavy Ion Forum
Freeze-out conditions at SPS and RHIC
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Europe/Zurich
40-SS-D01 (CERN)
40-SS-D01
CERN
Description
1. Recent HBT measurements by the CERES/NA45 experiment at the CERN SPS
by Harald Appelshäuser / IKF, Frankfurt
2. Two pion correlations in heavy ion collisions as measured by NA49 at the CERN SPS at 20A-158A GeV
by Stefan Kniege / IKF, Frankfurt
Particle interferometry measurements provide insight into the evolution of strongly interacting matter created in heavy ion collisions. In particular, within hydrodynamical models the transverse expansion velocity of matter at freeze-out is linked to the correlation lengths between two pions which are measured in experiments. Analysis and correction procedures of two-pion short-range correlations in central Pb+Pb collisions registered by the NA49 detector at 20A, 30A, 40A, 80A, and 158A GeV will be presented. The systematic uncertainties of the measurement will be discussed in detail. The dependence of two-pion Bose-Einstein correlations on transverse momentum, rapidity and energy will be shown and compared with the corresponding results at lower (AGS) and higher (RHIC) energies. The data will be interpreted and the freeze-out parameters will be extracted using a hydrodynamically-inspired approach.
3. Two particle intensity interferometry in heavy ion collisions as measured by the STAR experiment
by Mercedes López Noriega / CERN
In relativistic heavy ion collisions, two particle intensity interferometry (HBT) is a useful tool to study the space-time geometry of the particle emitting source. It also contains dynamical information that can be explored by studying the transverse momentum dependence of the apparent source size.
I will give an overview of the main HBT results in heavy ion collisions as measured by the STAR experiment at RHIC. I will present the results of identical particle correlations in heavy ion collisions at different energies, compare them with those from pp and dAu collisions, and discuss what they tell us about the geometrical and dynamical structure of the source at freeze-out. I will then discuss the results from the analysis with non-identical particles and show how they help us to better understand the dynamical evolution of the source.
4. UrQMD calculations on pion interferometry
by Qingfeng Li / FIAS, Frankfurt
The pion source at freeze-out is investigated with energies from AGS, SPS, to RHIC within the UrQMD approach. The CRAB program is employed as a tool to analyze the two-pion interferometry. The calculated transverse momentum, centrality, rapidity, system size, and beam energy dependence of the HBT radii are reasonably well in line with experimental data, except that the predicted R_O values in high-energy and central heavy ion collisions are larger as compared to data. The HBT-puzzle is seen throughout the energies, which should be analyzed more carefully.
5. Buda-Lund hydro model fits to HBT radii and single particle spectra in Pb+Pb collisions at various SPS energies
by András Ster / RMKI/ATKI, Budapest
We present simultaneous Buda-Lund hydro model fits to recent NA49 data on dn/dy and transverse momentum distributions as well as rapidity and transverse mass dependent two-particle Bose-Einstein or HBT correlations as measured in Pb+Pb collisions at SPS energies of 20, 30, 40, 80 and 158 AGeV.
The excitation function of the mean freeze-out temperature, the transverse temperature inhomogeneity, the system size, the mean transverse flow, the mean freeze-out time and the duration of particle emission is determined within the framework of the hydro model at the energy range of CERN SPS.
6. Comparison of particle emission in h+p and Pb+Pb reactions at various SPS energies with p+p and Au+Au reactions at RHIC
by Tamás Csörgö / RMKI, Budapest
This talk builds upon the results presented by András Ster in the previous talk, as well as on earlier results achieved with the help of the Buda-Lund hydro model to analyse the hadronic final states of h+p and Pb+Pb reactions at various CERN SPS energies, and p+p and Au+Au reactions at RHIC energies.
We see an indication that the fireball created in Pb+Pb collisions at CERN SPS has a more homogeneous temperature distribution, than the fireballs created in p+p and h+p reactions or in Au+Au collisions at RHIC.
Organiser(s): Yiota Foka and Nicolas Borghini
More information: http://home.cern.ch/a/alicedoc/www/chic/
by Harald Appelshäuser / IKF, Frankfurt
2. Two pion correlations in heavy ion collisions as measured by NA49 at the CERN SPS at 20A-158A GeV
by Stefan Kniege / IKF, Frankfurt
Particle interferometry measurements provide insight into the evolution of strongly interacting matter created in heavy ion collisions. In particular, within hydrodynamical models the transverse expansion velocity of matter at freeze-out is linked to the correlation lengths between two pions which are measured in experiments. Analysis and correction procedures of two-pion short-range correlations in central Pb+Pb collisions registered by the NA49 detector at 20A, 30A, 40A, 80A, and 158A GeV will be presented. The systematic uncertainties of the measurement will be discussed in detail. The dependence of two-pion Bose-Einstein correlations on transverse momentum, rapidity and energy will be shown and compared with the corresponding results at lower (AGS) and higher (RHIC) energies. The data will be interpreted and the freeze-out parameters will be extracted using a hydrodynamically-inspired approach.
3. Two particle intensity interferometry in heavy ion collisions as measured by the STAR experiment
by Mercedes López Noriega / CERN
In relativistic heavy ion collisions, two particle intensity interferometry (HBT) is a useful tool to study the space-time geometry of the particle emitting source. It also contains dynamical information that can be explored by studying the transverse momentum dependence of the apparent source size.
I will give an overview of the main HBT results in heavy ion collisions as measured by the STAR experiment at RHIC. I will present the results of identical particle correlations in heavy ion collisions at different energies, compare them with those from pp and dAu collisions, and discuss what they tell us about the geometrical and dynamical structure of the source at freeze-out. I will then discuss the results from the analysis with non-identical particles and show how they help us to better understand the dynamical evolution of the source.
4. UrQMD calculations on pion interferometry
by Qingfeng Li / FIAS, Frankfurt
The pion source at freeze-out is investigated with energies from AGS, SPS, to RHIC within the UrQMD approach. The CRAB program is employed as a tool to analyze the two-pion interferometry. The calculated transverse momentum, centrality, rapidity, system size, and beam energy dependence of the HBT radii are reasonably well in line with experimental data, except that the predicted R_O values in high-energy and central heavy ion collisions are larger as compared to data. The HBT-puzzle is seen throughout the energies, which should be analyzed more carefully.
5. Buda-Lund hydro model fits to HBT radii and single particle spectra in Pb+Pb collisions at various SPS energies
by András Ster / RMKI/ATKI, Budapest
We present simultaneous Buda-Lund hydro model fits to recent NA49 data on dn/dy and transverse momentum distributions as well as rapidity and transverse mass dependent two-particle Bose-Einstein or HBT correlations as measured in Pb+Pb collisions at SPS energies of 20, 30, 40, 80 and 158 AGeV.
The excitation function of the mean freeze-out temperature, the transverse temperature inhomogeneity, the system size, the mean transverse flow, the mean freeze-out time and the duration of particle emission is determined within the framework of the hydro model at the energy range of CERN SPS.
6. Comparison of particle emission in h+p and Pb+Pb reactions at various SPS energies with p+p and Au+Au reactions at RHIC
by Tamás Csörgö / RMKI, Budapest
This talk builds upon the results presented by András Ster in the previous talk, as well as on earlier results achieved with the help of the Buda-Lund hydro model to analyse the hadronic final states of h+p and Pb+Pb reactions at various CERN SPS energies, and p+p and Au+Au reactions at RHIC energies.
We see an indication that the fireball created in Pb+Pb collisions at CERN SPS has a more homogeneous temperature distribution, than the fireballs created in p+p and h+p reactions or in Au+Au collisions at RHIC.
Organiser(s): Yiota Foka and Nicolas Borghini
More information: http://home.cern.ch/a/alicedoc/www/chic/