Average transverse expansion velocities and global freeze-out temperatures in central Cu plus Cu, Au plus Au, and Pb plus Pb collisions at high energies at RHIC and LHC

摘要

The experimental invariant transverse momentum (pt) spectra of the charged pions and kaons, protons and antiprotons, produced at midrapidity in central (0-10%) Au + Au collisions at (s(nn))(1/2) = 62.4 GeV, central (0-10%) Cu + Cu collisions at (s(nn))(1/2) = 200 GeV, central (0-10%) Au + Au collisions at (s(nn))(1/2) = 200 GeV, and central (0-5%) Pb + Pb collisions at (s(nn))(1/2) = 2.76 TeV, measured by BRAHMS, STAR and ALICE collaborations, were analyzed using three different transverse expansion (blast-wave) models: Siemens-Rasmussen blast-wave model, Simple transverse flow model, and Simpli fied (hydro-inspired) blast-wave model of Schnedermann et al. Combined (simultaneous) minimum chi(2) fits of the experimental invariant pt spectra of the charged pions and kaons, protons and antiprotons with the above three model functions were conducted, using the identical selected optimal fitting ranges in pt in each studied collision system, and the values of the average transverse expansion velocity () and global kinetic freeze-out temperature (T-fo) and their dependencies on the collision system (< N-part >) and (s(nn))(1/2) were extracted. The combined (simultaneous) fits using Hagedorn formula with the (embedded) simple transverse flow describe well the experimental invariant pt spectra of the charged pions, kaons, protons and antiprotons in the whole measured range in region pt >= 0.5 GeV/c in the analyzed central heavy ion collisions at RHIC and LHC, reproducing qualitatively well all the established dependencies of the parameters and T-fo on the collision system (< N-part >) and (s(nn))(1/2). The obtained results were compared with those of the previous analyses of high energy heavy ion collisions.