three different EoS to investigate their effect on the extracted HBT radii. The first EoS, named the hadron gas (HG), describes a non-interacting gas of free hadrons [@Zschiesche:2002zr]. Included here are all reliably known hadrons with masses up to $2$ GeV, which is equivalent to the active degrees of freedom of the UrQMD model (note that this EoS does not contain any form of phase transition). This purely hadronic calculation serves as a baseline calculation to explore the effects of the change in the underlying dynamics - pure transport vs. hydrodynamic calculation. The second EoS, named the Bag Model EoS (BM), follows from coupling a bag model of massless quarks and gluons to a Walecka type of hadron gas including only SU(2) flavours (for details the reader is referred to [@Rischke:1995mt]). This EoS exhibits a strong first-order phase transition (with large latent heat) for all baryonic chemical potentials $\mu_B$. The third EoS, named the chiral+HG (CH), follows from a chiral hadronic $SU(3)$ Lagrangian and incorporates the complete set of baryons from the lowest flavour-$SU(3)$ octet, as well as the entire multiplets of scalar, pseudo-scalar, vector and axial-vector mesons [@Papazoglou:1998vr]. Additional baryonic degrees of freedom are included to produce a first-order 