Reconstructing the Freeze-out State in Pb+Pb Collisions at 158 A GeV/ c a

Tomášik, Boris; Wiedemann, Urs Achim; Heinz, Ulrich

doi:10.1556/aph.17.2003.1.11

Cited by 33 publications

(50 citation statements)

References 56 publications

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“…Let us elaborate on this aspect. Recall that the pion-chemical potential (µ π ) may reach a value of about 60 MeV in collision of lead nuclei at SPS energies [35] when T drops to 100 MeV. This will imply an enhancement in the rate of production of photons from the hadronic matter by approximately a factor of exp(µ π /T ) for every pion in the entrance channel, and also some increase due to Bose enhancement factor in the exit channel, if there is a pion there.…”

Section: B Single Photonsmentioning

confidence: 99%

Intensity interferometry of thermal photons from relativistic heavy-ion collisions

Srivastava

2005

Phys. Rev. C

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Intensity interferometry of thermal photons, having transverse momenta kT ≈ 0.1 -2.0 GeV, produced in relativistic collision of heavy nuclei is studied. It is seen to provide an accurate information about the temporal and spatial structure of the interacting system. The source dimensions and their kT dependence revealed by the photon interferometry, display a richness not seen in pion interferometry. We attribute this to difference in the source functions, the fact that photons come out from every stage of the collision and from every point in the system, and the fact that the rate of production of photons is different for the quark-gluon plasma, which dominates the early hot stage, and the hadronic matter which populates the last phase of the collision dynamics. The usefulness of this procedure is demonstrated by an application to collision of lead nuclei at the CERN SPS. Prediction for the transverse momentum dependence of the sizes for SPS, RHIC, and LHC energies are given.

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Section: B Single Photonsmentioning

confidence: 99%

Intensity interferometry of thermal photons from relativistic heavy-ion collisions

Srivastava

2005

Phys. Rev. C

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“…This has also been pointed out in [10]. Hence, incorporating accelerated longitudinal expansion we have the freedom to select τ f accoring to Eq.…”

Section: Initial Compression and Re-expansionmentioning

confidence: 63%

“…However, there is a subtle problem with this interpretation: If the system expands from a root mean sqare radius R rms of about 4.5 fm (as found by a calculation of the overlap of the colliding nuclei) to the measured R rms of about 8.5 fm (assuming R G = 6 fm), while at the same time the fireball front (for a Gaussian distribution, take e.g. R rms for the front) expands to a velocity of ∼ 0.5c, we may expect the following equations to approximate the problem [10]:…”

Section: Introductionmentioning

confidence: 69%

“…In [10], expressions (9), (11) and (12) have been used to fit the parameters of the shapes G(r) and H(η), the radial and longitudinal expansion velocities at freeze-out τ f , the freeze-out temperature T f and the temporal smearing ∆τ to experiment, thus providing the basic parameters for the fireball evolution described above. As a starting point for the investigations in this paper, we assume a box profile G(r) = θ(R B − r) for the radial distribution of thermalized matter.…”

Section: Hadron Emission From the Hypersurface With Timelike Normalmentioning

confidence: 99%

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Why a long-lived fireball can be compatible with Hanbury-Brown–Twiss measurements

Renk

2004

Phys. Rev. C

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The common interpretation of HBT data measured at top SPS energies leads to apparent source lifetimes of 6-8 fm/c and emission duration of approximately 2-3 fm/c. We investigate a scenario with continuous pion emission from a long-lived (∼ 16 fm/c) thermalized source in order to show that it is not excluded by the data. Starting from a description of the source's spacetime expansion based on gross thermodynamical properties of hot matter (which is able to describe a number of experimental observables), we introduce the pion emission function with a contribution from continuous emission during the source's lifetime and another contribution from the final breakup and proceed by calculating the HBT parameters Rout and R side . The results are compared with experimental data measured at SPS for 158 AGeV central Pb-Pb collisions. We achieve agreement with data, provided that some minor modifications of the fireball evolution scenario are made and find that the parameter Rout is not sensitive to the fireball lifetime, but only to the duration of the final breakup, in spite of the fact that emission takes place throughout the whole lifetime. We explicitly demonstrate that those findings do not alter previous results obtained within this framework.

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“…The critical curves of BO and KLNS models correspond to an energy density about 1.8 times above ε c . We interpret this result as a consequence of delayed thermalization and rapid expansion in both the longitudinal and transverse [47] direction which leads to fast cooling. In order to have a collectively behaving plasma that will be able to Figure 3: Curves in the 2L A , 2L B plane, which indicate the limits of anomalous J/ψ suppression in the BO [44] and KLNS [45] models, given by Eqs.…”

Section: Resultsmentioning

confidence: 90%

On energy densities reached in heavy-ion collisions at the CERN SPS

2003

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We present a few estimates of energy densities reached in heavyion collisions at the CERN SPS. The estimates are based on data and models of proton-nucleus and nucleus-nucleus interactions. In all of these estimates the maximum energy density in central Pb+Pb interactions is larger than the critical energy density ε c ≈ 0.7 GeV/fm 3 following from lattice gauge theory computations. In estimates which we consider as realistic the maximum energy density is about 2ε c . In this way our analysis gives some support to claims that deconfined matter has been produced at the CERN SPS. Any definite statement requires a deeper understanding of formation times of partons and hadrons in nuclear collisions. We also compare our results with implicit energy estimates contained in earlier models of anomalous J/ψ suppression in nuclear collisions.

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Reconstructing the Freeze-out State in Pb+Pb Collisions at 158 A GeV/ c a

Cited by 33 publications

References 56 publications

Intensity interferometry of thermal photons from relativistic heavy-ion collisions

Intensity interferometry of thermal photons from relativistic heavy-ion collisions

Why a long-lived fireball can be compatible with Hanbury-Brown–Twiss measurements

On energy densities reached in heavy-ion collisions at the CERN SPS

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