Performance of the ATLAS electromagnetic calorimeter under beam tests

The physics program at LHC is highly demanding in terms of detector performance. In particular, the A Toroidal LHC Apparatus (ATLAS) electromagnetic calorimeter has to match challenging requirements for energy, position and time resolutions. Calorimeter prototype and production modules have been tested under electron beams at CERN during the last three years. The results are presented and compared to ATLAS requirements.