Two-proton correlations from 158 A GeV Pb + Pb central collisions

Appelshäuser, H.; Bächler, J.; Bailey, S.; Barna, D.; Barnby, L. S.; Bartke, J.; Barton, R. A.; Betev, L.; Bialoovska, H.; Billmeier, A.; Blyth, C. O.; Bock, R.; Boimska, B.; Bormann, C.; Brady, F. P.; Brockmann, R.; Brun, R.; Bunčić, P.; Caines, H.; Carr, Lincoln D.; Cebra, D.; Cooper, G. E.; Cramer, J. G.; Cristinziani, M.; Csató, P.; Dunn, J.; Eckardt, V.; Eckhardt, F.; Ferguson, M. I.; Fischer, H. G.; Flierl, D.; Fodor, Z.; Foka, P.; Freund, P.; Friese, V.; Fuchs, Markus; Gabler, F.; Gál, János; Ganz, R.; Gaździcki, M.; Geist, W.; Gladyss, E.; Grebieszkow, J.; Günther, J.; Harris, J. W.; Hegyi, S.; Henkel, Timothy P.; Hill, L. A.; Hümmler, Holm Gero; Igo, G.; Irmscher, D.; Jacobs, P.; Jones, P. G.; Kadija, K.; Kolesnikov, V.; Kowalski, M.; Lasiuk, B.; Lednický, R.; Lévai, P.; Malakhov, A.; Margetis, S.; Markert, C.; Melkumov, G. L.; Mock, A.; Molnár, J.; Nelson, J. M.; Oldenburg, M.; Odyniec, G.; Pálla, G.; Panagiotou, A.; Petridis, A.; Piper, Anne Marie; Porter, R.; Poskanzer, A. M.; Prindle, D.; Pühlhofer, F.; Šuša, T.; Reid, J. G.; Renfordt, R.; Retyk, W.; Ritter, H. G.; Röhrich, D.; Roland, C.; Roland, G.; Rudolph, H.; Rybicki, A.; Sammer, T.; Sandoval, A.; Sann, H.; Semenov, A.; Schäfer, Erich; Schmischke, D.; Schmitz, N.; Schönfelder, Stefan; Seyboth, P.; Siklér, F.; Skrzypczak, E.; Snellings, Raimond; Squier, G.T.A.; Stock, R.; Ströbele, H.; Struck, C.; Szentpétery, I.; Sziklai, J.; Toy, M.; Trainor, T. A.; Trentalange, S.; Ullrich, T.; Vassiliou, M.; Veres, G. I.; Vesztergombi, G.; Voloshin, S.; Vranić, D.; Wang, F.; Weerasundara, D.; Wenig, S.; Whitten, C.; Wood, L.; Xu, N.; Yates, T. A.; Zimányi, J.; Zhu, X.; Zybert, R.

doi:10.1016/s0370-2693(99)01152-1

Cited by 24 publications

(13 citation statements)

References 32 publications

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“…Figure 4 shows the system dependence of the phase space densities and source radii for π ± , p andp. The p andp radii for P bP b are consistent with coalescence data at p T = 0, and pp interferometry results [37,38]. The π + and p phase space densities generally increase with system size.…”

Section: Endsupporting

confidence: 83%

(Anti)proton and pion source sizes and phase space densities in heavy ion collisions

Murray

Hölzer

2001

Phys. Rev. C

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NA44 has measured mid-rapidity deuteron spectra from AA collisions at √ s nn ≈ 18 GeV at the CERN SPS. Combining these spectra with published p,p andd data allows us to calculate, within a coalescence framework, p andp source sizes and phase space densities. These results are compared to π ± source sizes measured by Hanbury-Brown Twiss, HBT, interferometry and phase densites produced by combining pion spectra and HBT results. We also compare to pA results and to lower energy (AGS) data. Thep source is larger than the proton source at √ s nn = 17.3 GeV. The phase space densities of π + and p are not constant but grow with system size. Both π + and proton radii decrease with m T and increase with √ s nn . Pions and protons do not freezeout independently. The nature of their interaction changes as √ s nn and the π/p ratio increases. Relativistic heavy ion collisions provide a mechanism to heat and compress nuclear matter to temperatures and energy densities comparable to those of the early universe when it was still a plasma of quarks and gluons. Such a state may be fleetingly restored in these collisions where temperatures of T = 168 ± 3 MeV and energy densities ǫ = 3 GeV/fm 3 are observed [1,2]. These values are close to those of the phase transition found in lattice calculations [3]. If such a hot and dense state were formed one would expect a large increase in entropy and possibly a saturation of the density of particles in phase space. The coalescence of nucleons into deuterons is sensitive to both their spatial and momentum correlations. In this paper we report p,p and π + source sizes measured by coalescence and interferometry, and combine these with single particle spectra to derive phase space densities. The phase space densities depend on temperature, chemical potentials, and velocity fields in the system. This description of the final hadronic state serves as a boundary condition for models of possible quark gluon plasma production. We vary the total size of the system by studying P bP b, SP b, SS and pP b collisions. We also compare our results to lower energy AGS data where the π/p ratio is much lower. This comparison shows that the freeze-out of pions and protons is coupled.NA44 is a focusing spectrometer that uses conventional dipole magnets and superconducting quadrupoles to analyze the momentum of the produced particles and create a magnified image of the target in the spectrometer [4,5,6,7,8,9,10]. The systematic errors on the deuteron yields range from 14% for SP b to 9% for P bP b. The p andp spectra are corrected for feed-down from Λ and Σ decays using a GEANT simulation with the (Λ/p) and (Σ/p) ratios taken from the RQMD model [9,10,11]. The systematic error was estimated by varying these ratios by ±25%. These errors are slightly correlated for p andp. Fig. 1 shows NA44 deuteron spectra and previously published proton spectra at y = 1.9-2.3 as a function of m T /A [12]. The centrality is ≈ 10% for SS, SP b and P bP b. The spectra get flatter for the larger systems consistent with a hig...

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Section: Endsupporting

confidence: 83%

(Anti)proton and pion source sizes and phase space densities in heavy ion collisions

Murray

Hölzer

2001

Phys. Rev. C

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“…The model [24] explicitly considers rapid collective expansion of the collision zone in a density matrix approach for coalescence and finds the connection between the value of B 2 and the volume of homogeneity (the It is important to note that the radius parameters used for comparison should be taken at similar m t values in both the HBT and coalescence analysis, i.e., at m t near the nucleon mass. For this calculation the dependence of HBT radii on N part measured for pions at m t = 0.2 GeV/ c 2 [44] was scaled to m t Ӎ m p using the m t dependence of HBT radius parameters obtained from the correlation study of [44], pp [45], and KK [46,47] pairs each of them measured at different m t values in central 158A GeV Pb+ Pb collisions.…”

Section: Discussionmentioning

confidence: 99%

Energy and centrality dependence of deuteron and proton production inPb+Pbcollisions at relativistic energies

Antičić¹,

Baatar²,

Barna³

et al. 2004

Phys. Rev. C

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129

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The transverse mass m t distributions for deuterons and protons are measured in Pb+ Pb reactions near midrapidity and in the range 0 Ͻ m t − m Ͻ 1.0 ͑1.5͒ GeV/ c 2 for minimum bias collisions at 158A GeV and for central collisions at 40 and 80 A GeV beam energies. The rapidity density dn / dy, inverse slope parameter T and mean transverse mass ͗m t ͘ derived from m t distributions as well as the coalescence parameter B 2 are studied as a function of the incident energy and the collision centrality. The deuteron m t spectra are significantly harder than those of protons, especially in central collisions. The coalescence factor B 2 shows three systematic trends. First, it decreases strongly with increasing centrality reflecting an enlargement of the deuteron coalescence volume in central Pb+ Pb collisions. Second, it increases with m t . Finally, B 2 shows an increase with decreasing incident beam energy even within the SPS energy range. The results are discussed and compared to the predictions of models that include the collective expansion of the source created in Pb+ Pb collisions.

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“…NA49 Collaboration has measured the correlation Φ p ⊥ of the pion transverse momentum (Pb+Pb at 158 A GeV) [44] obtaining Φ exp p ⊥ = (0.6±1) MeV. This value is the sum of two contributions: Φ st p ⊥ = (5 ± 1.5) MeV, the measure of the statistical two-particle correlation, and Φ tt p ⊥ = (−4 ± 0.5) MeV, the anti-correlation from limitation in two-track resolution.…”

Section: Transverse Momentum Fluctuationsmentioning

confidence: 99%

Non-extensive statistical effects in high-energy collisions

2009

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Abstract. Following the basic prescriptions of the relativistic Tsallis' non-extensive thermostatistics, we investigate from a phenomenological point of view the relevance of non-extensive statistical effects on relativistic heavy-ion collisions observable, such as rapidity spectra of net proton production, transverse momentum distributions and transverse momentum fluctuations. Moreover, we study the nuclear and the subnuclear equation of state, investigating the critical densities of a phase transition to a hadron-quarkgluon mixed phase by requiring the Gibbs conditions on the global conservation of the electric and the baryon charges. The relevance of small deviations from the standard extensive statistics is studied in the context of intermediate and high energy heavy-ion collisions.PACS. 25.75.-q Relativistic heavy-ion collisions -25.75.Nq Quark deconfinement, quark-gluon plasma production, and phase transitions -05.90.+m Other topics in statistical physics, thermodynamics, and nonlinear dynamical systems

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Two-proton correlations from 158 A GeV Pb + Pb central collisions

Cited by 24 publications

References 32 publications

(Anti)proton and pion source sizes and phase space densities in heavy ion collisions

(Anti)proton and pion source sizes and phase space densities in heavy ion collisions

Energy and centrality dependence of deuteron and proton production inPb+Pbcollisions at relativistic energies

Non-extensive statistical effects in high-energy collisions

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