A novel method for the determination of the radiation damage effects in silicon detectors

The result of a study about the effects of radiation damage on silicon detectors, carried out using the LBIC (light beam induced current) technique are thoroughly reported. As this technique is capable to detect any change in the minority carriers diffusion lenght associated to radiation damage, it was possible to show that the main degradation effect, associated to fast neutron irradiation up to a fluence of 1013ncm2, is a reduction of the lifetime of the minority carriers, which reduces the collection efficiency. A secondary effect which has been also clearly detected is a drift of the Fermi level, presumably associated to damage-induced compensation effects.