Measurement of proton-induced radiation damage effects in double-sided silicon microstrip detectors

The electrical characteristics of double-sided n-type silicon microstrip detectors were investigated after those detectors had received proton irradiation up to a fluence equivalent to 1.7×1013 1 MeV neutrons/cm2. This fluence is about twice as much as is expected for the CDF SVX II innermost layer during its first year. It is also approximately equal to the fluence expected at a radius of 12 cm from an interaction point during the first three years of operation of an LHC experiment. The detectorsʹ p- and n-side leakage currents and their depletion voltages responded to the damage in a manner consistent with present models. Their total capacitance per active length increased by (2.0±0.7) × 10−14 pF cm/[1MeV neutron] on the p-side. Their total capacitance increased by (1.5±0.1) × 10−13 pF cm2/[1 MeV neutron] on the n-side for a particular double-metal geometry. Their coupling capacitance was unchanged by this fluence. The study required development of a new method for determining full-depletion voltage; that method is also presented here.