(Anti)Proton and Pion Source Sizes and Phase Space Densities in Heavy Ion Collisions

Abstract

NA44 has measured mid-rapidity deuteron spectra from AA collisions at sqrt{s}=18GeV/A at the CERN SPS. Combining these spectra with published proton, antiproton and antideuteron data allows us to calculate, within a coalescence framework, proton and antiproton source sizes and phase space densities. These results are compared to pion source sizes and densities, pA results and to lower energy (AGS) data. The antiproton source is larger than the proton source at sqrt{s}=18GeV/A. The phase space densities of pions and protons are not constant but grow with system size. Both pi+ and proton radii decrease with transverse mass and increase with sqrt{s}. Pions and protons do not freeze-out independently. The nature of their interaction changes as sqrt{s}, and the pion/proton ratio increases.

arXiv comment4 pages, Latex 2.09, 3 eps figures. Changes for January 2001. The proton source size is now calculated assuming a more realistic Hulthen, rather than Gaussian, wavefunction. A new figure shows the effect of this change which is important for small radii. A second new figure shows the results of RQMD calculations of the proton source size and phase density. Because of correlations between position and momentum coalesence does not show the full proton source size. The paper has been streamlined and readability improved

References in corpus (21)

• Chemical Equilibration in Pb+Pb Collisions at the SPS
• Particle Interferometry for Relativistic Heavy-Ion Collisions
• Flavor Production in Pb(160AGeV) on Pb Collisions: Effect of Color Ropes and Hadronic Rescattering
• Coalescence and flow in ultra-relativistic heavy ion collisions
• Bose-Einstein Correlations for Three-Dimensionally Expanding, Cylindrically Symmetric, Finite Systems
• A new cross term in the two-particle Hanbury-Brown-Twiss correlation function
• Model Independent Features of the Two-Particle Correlation Function
• Effects of collective expansion on light cluster spectra in relativistic heavy ion collisions
• Lifetimes and Sizes from Two-Particle Correlation Functions
• Antideuteron yield at the AGS and coalescence implications
• Two-pion correlations in Au+Au collisions at 10.8 GeV/c per nucleon
• Universal pion freeze-out phase-space density
• Strange Meson Enhancement in PbPb Collisions
• Antiproton Production and Antudeuteron Production Limits in Relativistic Heavy Ion Collisions
• Proton and Antiproton Distributions at Mid-Rapidity in Proton-Nucleus and Sulphur-Nucleus Collisions
• Meson phase space density from interferometry
• Two-proton correlations from 158 AGeV Pb+Pb central collisions
• Charged Kaon and Pion Production at Midrapidity in Proton Nucleus and Sulphur Nucleus Collisions
• New Scaling Law for Deuteron Production in Ultra-Relativistic Nucleus Nucleus Collisions
• Measurements of Neutrons in 11.5 A GeV/c Au+Pb Heavy Ion Collisions
• Two-Proton Correlations near Midrapidity in p+Pb and S+Pb Collisions at the CERN SPS

Cited by in corpus (4)

• Nuclear coalescence from correlation functions
• Rapidity dependence of deuteron production in Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV
• The freeze-out mechanism and phase-space density in ultrarelativistic heavy-ion collisions
• Kaon Phase Space Density in Heavy Ion Collisions