Pion Energy Reconstruction Methods for the ATLAS Electromagnetic and Hadronic Endcap Calorimeters

In preparations for the ATLAS experiment at the Large Hadron Collider at CERN, sections of the Electromagnetic Endcap Calorimeter (EMEC) and Hadronic Endcap Calorimeter (HEC) were subjected to particle beams in the summer of 2002. The EMEC and HEC are non-compensating calorimeters with e/h > 1: electromagnetic showers will, on average, have a higher energy response than hadronic showers initiated by particles of the same energy. To reconstruct the energy of pions, the method of software compensation is investigated. Several beam energy dependent weighting schemes are studies, using calorimeter depth weights and cluster energy density weights. Finally, a beam energy independent cluster energy density weighting scheme is studied. Partial software compensation is achieved for pion energy reconstruction, improving the energy resolution and response linearity of the calorimeters.