A fully integrated Boltzmann+hydrodynamics approach: Multiplicities, transverse dynamics and HBT

We present a coupled Boltzmann and hydrodynamics approach to relativistic heavy ion reactions. This hybrid approach is based on the Ultra-relativistic Quantum Molecular Dynamics (UrQMD) transport approach with an intermediate hydrodynamical evolution for the hot and dense stage of the collision. This implementation allows to compare microscopic transport calculations with hydrodynamic calculations using exactly the same initial conditions and freeze-out procedure. Here, the results of the different calculations for particle multiplicities, the mean transverse mass excitation function and the HBT radii at all SPS energies are discussed in the context of the available data.