Reconstructing the freeze-out state in Pb+Pb collisions at 158 AGeV/c

Tomášik, Boris, 1972- Reconstructing the freeze-out state in Pb+Pb collisions at 158 AGeV/c / Boris Tomášik, Urs Achim Wiedemann, Ulrich Heinz. -- For a class of analytical parametrizations of the freeze-out state of relativistic heavy ion collisions, we perform a simultaneous analysis of the single-particle m(perpendicular to)-spectra and two-particle Bose-Einstein correlations measured in central Pb+Pb collisions at the CERN SPS. The analysis includes a full model parameter scan with chi(2) confidence levels. A comparison of different transverse density profiles for the particle emission region allows for a quantitative discussion of possible model dependencies of the results. Our fit results suggest a low thermal freeze-out temperature T approximate to 95 +/- 15 MeV and a large average transverse flow velocity (υ) over bar (perpendicular to) approximate to 0.55 +/- 0.07. Moreover, the fit favours a box-shaped transverse density profile over a Gaussian one. We discuss the origins and the consequences of these results in detail. In order to reproduce the measured pion multiplicity our model requires a positive pion chemical potential. A study of the pion phase-space density indicates mu(pi) approximate to 60MeV for T = 100MeV.

In Acta physica Hungarica : heavy ion physics. -- Budapest : Akademiai Kiado, 2003. -- ISSN 1219-7580. -- Vol. 17, no. 1 (2003), pp. 105-143

1. heavy ion collisions 2. nukleárne kolízie

I. Wiedemann, Urs Achim
II. Heinz, Ulrich
III. Acta physica Hungarica : heavy ion physics. -- Vol. 17, no. 1 (2003), pp. 105-143

53
BB301