Performances of the FINUDA Drift Chambers in a Cosmic Ray Test

We report on a cosmic ray test of the FINUDA drift chambers performed inside the FINUDA detector without a magnetic field. From an accurate study of the drift cell space^-time relations we determine both the spatial resolution and the mechanical alignment of the chambers. The chambers operate with a non-saturated 70;% He - 30% iC_4H_10 as mixture and the drift cells are modeled using GARFIELD. After alignment of the drift chamber system, we find a spatial resolution averaged over the entire drift cell and over all angles of incidence of about 140 μm.