Ultrarelativistic heavy-ion collisions within two-fluid model with pion emission

Mishustin, I. N.; Russkikh, V. N.; Satarov, L. M.

doi:10.1016/0375-9474(89)90192-9

Cited by 38 publications

(44 citation statements)

References 15 publications

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“…In particular, this model also leads to a high rapidity projectile contribution centered around y ~ 2.5 as required by energy-momentum and baryon conservation. The rather large values of these stopping lengths are surprizing in view previous expectations basedon p+ A at higher energies [4,15]. Also with Ls = 26 fm, the fraction of projectile baryons in the central fireball is only fs '"" 1/3 for Si +Au.…”

supporting

confidence: 67%

Nuclear transparency in 15A-GeV Si+Au reactions?

Chapman

Gyulassy

1991

Phys. Rev. Lett.

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Recent data on central Si+Au collisions at 15 AGe V are shown to imply an unexpected high degree of nuclear transparency. The paucity of observed midra.pidity protons and pions suggests that up to one half of the projectile nucleons may lose less than one unit of rapidity after traversing 5-10 fm of nuclear matter. 25.70.Np, 13.85.Ni The first detailed spectra of p, 1r±, and J<± from central Si + Au reactions 14.6 AGeV /c have been reported recently by the E802 collaboration [1] at the AGS. These data are of interest in connection with estimating the nuclear stopping power and assessing whether high baryon density matter can be produced in nuclear collisions.Previous indirect data on transverse energy spectra and leading baryon spectra have been interpreted [2] as evidence for a large amount of nuclear stopping in such reactions. However, in Ref. [3] we noted that the paucity of pions and the shape of the proton rapidity distribution measured by E802 [1] were more indicative of nuclear transparency at least for light ion induced reactions. Our aim in this letter is to analyze the new data in detail and to estimate the nuclear stopping power in this reaction using a multicomponent firestreak model. 1The data that we focus on are shown in Figs. 1-3. The p, 1r-, J<± rapidity densities in central Si+Au collisions are shown in the upper panels. The lower panels show the transverse momentum slope parameter, T(y), obtained by fitting the invariant distributions at each rapidity with exp ( -m1./T(y)). The curves and histograms show the results based on the models discussed below. Also shown are extrapolations of the E814 leading neutron data[2] from a 0.8 degree cone assuming the above m1. distribution with T varied between 0.1 to 0.2 GeV for their ET > 13 GeV trigger.Based on p +A ---+ p +X data at energies Elab ~ 100 GeV [4], it was expected that in central Si +Au reactions the average rapidity of projectile baryons would be shifted downward by ~y "' 2.5 while the rapidity of participant target baryons should be shifted upward by ~y ~ 1. Therefore a substantial amount of equilibration between projectile and target baryons was expected to occur at 15 AGeV where the total rapidity gap is only 3.5. We therefore compare the data first with the firestreak model [5]. The short dashed curves in Figs. 1 and 3 show the results "Obtained with a cut on impact parameters b::::; 2.9 fm. The severe discrepancy between the data and the calculated results is obvious. No reasonable variation of the freeze-out density was found to improve this situation. Also shown by the long dashed curves in Fig.1, are the results using the Landau hydrodynamic fireball of Ref. [2]. While the proton distribution is in agreement with the extrapolated E814 data, it fails to account for the ramp form of E802 proton data, the difference between the pion and proton slope parameters, and the absolute pion yield. In Re£.[6] a hydrochemical version of the fireball model was able to reproduce the pion and kaon spectra, but that model also failed t...

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supporting

confidence: 67%

Nuclear transparency in 15A-GeV Si+Au reactions?

Chapman

Gyulassy

1991

Phys. Rev. Lett.

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“…Inserting different equations of state, particularly with and without the plasma EOS, into the one-, two-, or three-fluid hydrodynamic model [29][30][31][32] one can study the properties of the particle collective flow at various incident energies [15][16][17]21]. The microscopic models, developed to describe heavy-ion collisions in a wide range of bombarding energies, e.g.…”

Section: Introductionmentioning

confidence: 99%

Microscopic study of energy and centrality dependence of transverse collective flow in heavy-ion collisions

et al. 2000

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The centrality dependence of directed and elliptic flow in light and heavy systems of colliding nuclei is studied within two microscopic transport models at energies from 1A GeV to 160A GeV. The pion directed flow has negative slope in the midrapidity range irrespective of bombarding energy and mass number of the colliding ions. In contrast, the directed flow of nucleons vanishes and even develops antiflow in the midrapidity range in (semi)peripheral collisions at energies around 11.6A GeV and higher. The origin of the disappearance of flow is linked to nuclear shadowing. Since the effect is stronger for a light system, it can be distinguished from the similar phenomenon caused by the quark-gluon plasma formation. In the latter case the disappearance of the flow due to the softening of the equation of state should be most pronounced in collisions of heavy ions. The centrality dependence of the elliptic flow shows that the maximum in the v 2 (b) distribution is shifted to very peripheral events with rising incident energy, in accord with experimental data. This is an indication of the transition from baryonic to mesonic degrees of freedom in hot hadronic matter.PACS numbers: 25.75.Ld, 24.10.Lx

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“…Thus, the three-fluid model accounts for the non-equilibrium situation during the compression stage of heavy-ion collisions. The coupling between the projectile and target fluids is calculated assuming free binary NN-collisions [8].…”

Section: Modelmentioning

confidence: 99%

On the observation of phase transitions in collisions of elementary matter

Paech¹,

Reiter²,

Dumitru³

et al. 2001

Nuclear Physics A

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We investigate the excitation function of directed flow, which can provide a clear signature of the creation of the QGP and demonstrate that the minimum of the directed flow does not correspond to the softest point of the EoS for isentropic expansion. A novel technique measuring the compactness is introduced to determine the QGP transition in relativistic-heavy ion collisions: The QGP transition will lead to higher compression and therefore to higher compactness of the source in coordinate space. This effect can be observed by pion interferometry. We propose to measure the compactness of the source in the appropriate principal axis frame of the compactness tensor in coordinate space. MotivationThe primary goal for the investigation of heavy-ion collisions is to test the equation of state (EoS) of hot and dense matter far off the ground state, especially with view on possible phase transitions, e.g. to the Quark-Gluon-Plasma (QGP) [1]. Indeed, collective flow phenomena are sensitive indicators for thermodynamically abnormal matter [2]. In the case of a first-order phase transition to a QGP, an isentropic expansion proceeds through a stage of phase coexistence which should lead to signatures in the observables. The first ideas to investigate this phenomenon occured in the mid-seventies [3]. In this paper we investigate the excitation function of directed flow, as well as the compactness in heavy-ion collisions. ModelTo investigate quantitatively the experimental observables, we perform 1-fluid and 3-fluid (3+1)-dimensional relativistic hydrodynamic calculations. That is, we solve numerically the continuity equations for the energy-momentum tensor, ∂ µ T µν = 0, and the net baryon current, ∂ µ N µ B = 0. Detailed discussions of (3+1)-d numerical solutions for hydrodynamical compression and expansion can be found e.g. in [4]. We shall employ two * Invited speaker at CRIS 2000, 3rd Catania Relativistic Ion Studies,

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Ultrarelativistic heavy-ion collisions within two-fluid model with pion emission

Cited by 38 publications

References 15 publications

Nuclear transparency in 15A-GeV Si+Au reactions?

Nuclear transparency in 15A-GeV Si+Au reactions?

Microscopic study of energy and centrality dependence of transverse collective flow in heavy-ion collisions

On the observation of phase transitions in collisions of elementary matter

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