Commissioning of the ATLAS Liquid Argon Calorimeter

The Liquid Argon (LAr) calorimeter provides electromagnetic and forward hadronic calorimetry for the ATLAS experiment at the LHC. Since the installation of the calorimeter in 2006, the electronic calibration and readout systems have been exercised with regular calibration and cosmic runs, and with three days of LHC single beam runs. These datasets have enabled detailed studies of calibration procedures, pulse shape models, uniformity of response, detector noise, and the possibility of noise and cosmic rays as backgrounds to jet and missing energy measurements. They have allowed a precise understanding of the detector behavior. The LAr calorimeter is well prepared for LHC collisions, which we hope for by the end of 2009.