%0 Journal Article
%T Microscopic study of freeze-out in relativistic heavy ion collisions at SPS energies
%A L. V. Bravina
%A I. N. Mishustin
%A J. P. Bondorf
%A Amand Faessler
%A E. E. Zabrodin
%J Physics
%D 1999
%I arXiv
%R 10.1103/PhysRevC.60.044905
%X The freeze-out conditions in the light (S+S) and heavy (Pb+Pb) colliding systems of heavy nuclei at 160 AGeV/$c$ are analyzed within the microscopic Quark Gluon String Model (QGSM). We found that even for the most heavy systems particle emission takes place from the whole space-time domain available for the system evolution, but not from the thin ''freeze-out hypersurface", adopted in fluid dynamical models. Pions are continuously emitted from the whole volume of the reaction and reflect the main trends of the system evolution. Nucleons in Pb+Pb collisions initially come from the surface region. For both systems there is a separation of the elastic and inelastic freeze-out. The mesons with large transverse momenta, $p_t$, are predominantly produced at the early stages of the reaction. The low $p_t$-component is populated by mesons coming mainly from the decay of resonances. This explains naturally the decreasing source sizes with increasing $p_t$, observed in HBT interferometry. Comparison with S+S and Au+Au systems at 11.6 AGeV/$c$ is also presented.
%U http://arxiv.org/abs/nucl-th/9907061v1