A study of the barrel presampler in the 1997 testbeam at CERN

In this note, we present the performance of the first final ATLAS barrel presampler module tested in beam at CERN in 1997. The electronic noise is measured in single presampler channels, as well as in various groups of cells. We show that it can be reduced by about 30% by using the optimal filtering. Then, the response of the presampler to a 100 GeV electron beam is studied, with various amounts of upstream material. We show that the presampler allows to compensate for the energy loss in the upstream material and thus maintain the energy resolution of the electromagnetic calorimeter at the level required for ATLAS.