Characterization of the ALICE Silicon Drift Detectors using an infrared laser

The Inner Tracking System of the ALICE experiment at LHC uses Silicon Drift Detectors in two cylindrical layers located at radial distance of ≈ 15 and ≈ 24 cm from the beam axis. The spatial resolution of silicon drift detectors can be strongly affected by inhomogeneities of the doping concentration, temperature effects and non-linearity of the drift potential distribution. Before the detector commissioning, an extensive study and characterization of all the produced detectors has been performed. For this purpose, a specific measuring station, based on a laser mapping system, has been developed.