Performances of drift chambers in the HARP Experiment at CERN

The neutrino physics recorded significant progress by the discovery of oscillation of solar and atmospheric neutrinos. To study in details the phenomenology of massive neutrinos new machines - neutrino factories - will be necessary the design of which depends on specific prior developments and experiments. The HARP experiment is placed in this frame and is intended to measure thoroughly and precisely the hadron (particularly pions) production cross section in the proton-nucleus interactions for low incident momenta (2 to 15 GeV/c). The experimental setup aims at a 4π acceptance and this thesis is oriented to the front spectrometer, namely to the drift chambers which allow reconstructing the trajectories of the fastest charged particles. The simulation of the reconstruction programs is here presented in the frame of GEANT4, special adapted by the Collaboration. The delicate issues of chambers' alignment is treated and followed by a first evaluation of the chamber performances: designed efficiency and reconstruction efficiency. The development of the global reconstruction program will allow a physical analysis of the HARP data.