The ATLAS fast calorimeter simulation FastCaloSim

The FastCaloSim calorimeter simulation was developed to provide a reasonably realistic but still fast simulation of the ATLAS calorimeter system. Parametrizations of electromagnetic and hadronic calorimeter showers are used to deposit particle energies in the detailed calorimeter structure. In the present document a short overview of the fast calorimeter simulation principle is presented. This is followed by a comparison of individual particle signatures and event properties to the full Geant 4 based ATLAS detector simulation as well as to data collected by the ATLAS experiment in proton-proton collisions at a center-of-mass energy of √s = 7 TeV in early 2010.