Performance of a liquid argon Accordion calorimeter with fast readout

Abstract A prototype lead-liquid-argon electromagnetic calorimeter with parallel plates and Accordiongeometry has been equipped with high speed readout electronics and tested with electron and muon beams at the CERN SPS. For a response peaking time of about 35 ns, fast enough for operation at the future hadron colliders, the energy resolution for electrons is 9.6%/√ E [GeV] with a local constant termof 0.3% and a noise contribution of 0.33 E[ GeV ] . The spatial accuracy achieved with a detector granularity of 2.7 cm is 3.7 mm E[ GeV ] and the angular resolution12 mrad at 60 GeV.