Test su fascio di prototipi del rivelatore a pixel per l'esperimento ATLAS

Silicon pixel detectors, developed to meet LHC requirements, were tested within the ATLAS collaboration in the H8 beam at CERN. Different sensor designs were studied using various versions of front end electronics developed during the R&D process. In this thesis a detailed experimental study of the overall performance of both irradiated and unirradiated detectors is presented, with special enphasis on efficiency, charge collection and spatial resolution. For the first time their dependence on timewalk is carefully investigated. Possible solutions to avoid spatial resolution deterioration due to timewalk are presented and discussed.