Performance of the ATLAS liquid argon endcap calorimeter in the pseudorapidity region 2.5<|η|<4.02.5<|η|<4.0 in beam tests

The pseudorapidity region 2.5<|η|<4.02.5<|η|<4.0 in ATLAS is a particularly complex transition zone between the endcap and forward calorimeters. A set-up consisting of 14 resp. 18 of the full azimuthal acceptance of the ATLAS liquid argon endcap and forward calorimeters has been exposed to beams of electrons, pions and muons in the energy range E⩽200GeV at the CERN SPS. Data have been taken in the endcap and forward calorimeter regions as well as in the transition region. This beam test set-up corresponds very closely to the geometry and support structures in ATLAS. A detailed study of the performance in the endcap and forward calorimeter regions is described. The data are compared with MC simulations based on GEANT 4 models.