th / 0 20 80 68 v 1 2 9 A ug 2 00 2 1 Collective flow and HBT radii from a full 3 D hydrodynamic model with early chemical freeze out

From the particle ratios and the transverse momentum spectra of hadrons in relativistic heavy ion collisions, one can obtain chemical freeze-out temperature T ch and thermal freeze-out temperature T th through the analyses of statistical models [1]. These temperatures are usually different from each other at the AGS, SPS and RHIC energies, i.e., T ch ∼ 160-200 MeV while T th ∼ 100-140 MeV. This provides the following picture of space-time evolution of hadronic matter: The equilibrated system produced in the early stage of collisions first undergoes the chemical freeze-out where the observed particle ratios are fixed and then goes through the thermal freeze-out where the momentum distribution is fixed. However, one assumes T ch = T th in the conventional hydrodynamic models. As a result, one cannot describe the particle ratios and spectra simultaneously. As a first trial, we incorporate the early chemical freeze-out into the hadronic equation of state (EOS) [2] for μB = 0 case [3] and investigate its effects on hydrodynamic evolution such as radial flow, elliptic flow and HBT radii by using a fully three-dimensional hydrodynamic model (3D hydro) [4].