Characterization of non-uniformly irradiated silicon micro-strip sensors

We describe a method we used to characterize micro-strip sensors, which were non-uniformly irradiated up to a fluence of ∼1014 1 MeV equivalent neutrons per cm2. The method allows for a complete bidimensional mapping of the sensor characteristics over the entire active area. Information is gathered through the Q-V characteristic, measured scanning the sensor with an infra-red laser source. Q-V characteristics are then fitted to a simple analytical model, which returns local full-depletion voltages, carrier lifetimes, etc. With the present method one can even obtain the profile of the absorbed fluence. The development and tuning of the present method have been done in the context of the R&D programs for the micro-strip forward tracker of the BTeV experiment at the Tevatron.