Electron and Photon Reconstruction with Fully Simulated Events in the CMS/LHC Experiment.

The CMS/LHC experiment is building a high performance electromagnetic calorimeter. The detailed simulation of the calorimeter, the tracker material in front of it and the high magnetic field, were essential in the design and development phases. Recently, fully simulated events have been used in the evaluation of the DAQ and High Level Trigger design. The current strategy for the reconstruction of the electrons and photons is presented as well as indications of its impact on physics performance.