Mesure de la réponse des calorimètres centrales d'ATLAS à des pions chargés d'énergie comprise entre 3 et 250 GeV. Calibration des photomultiplicateurs du calorimètre hadronique d'ATLAS avec un système laser

The Large Hadron Collider (LHC) is the machine that will provide the highest ever produced energy in the center of mass, reaching the value of √ s=14 TeV for proton-proton collisions. The work presented in this thesis is oriented into two axis: the calibration of the photomultipliers of the ATLAS hadronic calorimeter (TileCal) with a LASER system and the study of the response of the ATLAS calorimeters (LAR+TileCal) exposed to pions with energy between 3 and 250 GeV at 2004 combined test beam. After a description of the ATLAS detector, the LASER calibration system is described; after the description of the mechanical and electronical components, the results of the LASER system commissioning and of the TileCal photomulipliers calibration are presented. The last two chapters are dedicated to the study of the TileCal response to high energy pions (20-250 GeV) and low energy pions (3-10 GeV) respectively.