ATLAS calorimeter results

This report presents results obtained with the ATLAS detector. These are based on the first Large Hadron Collider (LHC) proton-proton collision data accumulated up to December 2009 at 900 GeV and at 2.36 GeV center of mass energy. The performances of the ATLAS calorimeter system are presented. Highlights are put on its responses to missing transverse energy, jets, photons and electrons including combined performances with the tracking system. In addition it shows the very good description of the data by the ATLAS Monte Carlo simulation. Finally early physics results such as the measured reconstructed γγ invariant mass are given, illustrating the very good performances of the calorimeter system.