Local Hadron Calibration in Atlas.

The method of Local Hadron Calibration is used in Atlas as one of two major calibration schemes for hadronic signals like jets and missing transverse energy. Starting from noise suppressed energy clusters a modular chain of classification and corrections steps are applied to distinguish electro-magnetic from hadronic deposits and to compensate invisible energy losses, deposits in dead material and noise threshold related losses. Finally jet-level corrections take care of missing energy due to particles never reaching the calorimeter. The method and its application to single charged and neutral pion simulations as well as di-jet simulations are presented. First comparisons of MinBias simulations and real Atlas data at sqrt(s)=900 GeV are shown.