The ATLAS Liquid Argon Calorimeter at the LHC: Overview and Performance

The Liquid Argon (LAr) Calorimeters provide electromagnetic and forward hadronic calorimetry measurements for the ATLAS experiment. Since 2008, all parts of the LAr calorimeters are readout. An overview of the LAr calorimeters, including hardware status and performance of the calibration system and calorimeter trigger, is presented. Results on timing alignment, uniformity and energy flow, extracted from cosmics and collision data, are presented and show the excellent performance of the LAr calorimeters 3 months after the start of LHC operation at 7 ev{} energy in center of mass.