Two-pion interferometry in heavy ion collisions at HIRFL-CSR energy

We examine the two-pion Hanbury-Brown-Twiss(HBT) interferometry for the particle-emitting source produced in heavy ion collisions at HIRFL-CSR energy.The source evolution is described by relativistic hydrodynamics with three kinds of equations of state for chemical equilibrium(CE),chemical freeze-out(CFO),and partial chemical equilibrium(PCE) models,respectively.We investigate the effects of particle decay,multiple scattering,and source collective expansion on the two-pion interferometry results.We find that the HBT radii of the evolution source for the CFO and PCE models are smaller than that for the CE model.The HBT lifetime for the CFO model is smaller than those for the PCE and CE models.The particle decay increases the HBT radius and lifetime while the source expansion decreases the HBT radius.The multiple scattering effect on the HBT results can be neglected based on our model calculations.