Irradiated silicon particle detectors

The electric field distribution inside heavily irradiated silicon particle detectors is deduced using observations of α-particle and minimum ionising particle signals. In these detectors α-particle signals are observed for both p+ and n+ side illumination even when the detector is only partially depleted. The observations indicate that the electric field distribution within the partially depleted detector has the contribution expected from a uniform space charge, as in unirradiated detectors, together with a strong, short range, local electric field in the vicinity of the p+ electrode and a non-zero electric field in the remaining part of the detectors. A mathematical model is derived from the proposed structure of the electric field and it is shown that it closely resembles the observed data. A follow-up study is also made of the charge collection efficiency of the detectors which investigates the temperature dependence of the field pattern. (author)