Performance of the ATLAS hadronic end-cap calorimeter in beam tests

Abstract Modules of the ATLAS liquid argon Hadronic End-cap Calorimeter (HEC) were exposed to beams of electrons, muons and pions in the energy range 6⩽ E ⩽200 GeV at the CERN SPS. A description of the HEC and of the beam test setup are given. Results on the energy response and resolution are presented and compared with simulations. The ATLAS energy resolution for jets in the end-cap region is inferred and meets the ATLAS requirements.