The simulation of the CMS electromagnetic calorimeter

The CMS Collaboration has developed a detailed simulation of the electromagnetic calorimeter (ECAL), which has been fully integrated in the collaboration software framework CMSSW. The simulation is based on the Geant4 detector simulation toolkit for the modelling of the passage of particles through matter and magnetic field. The geometrical description of the detector is being re-implemented using the DetectorDescription language, combining an XML based description of with the algorithmic definition of the position of the elements. The ECAL simulation software is fully operational and has been validated using real data from the ECAL test beam experiment that took place in summer 2006.