Depletion voltage and charge collection for highly irradiated silicon microstrip detectors with various initial resistivities

We have irradiated p-on-n silicon microstrip detectors of initial bulk resistivity between 0.2 and 2.7 k/spl Omega/-cm with 55 MeV protons to fluences of 0.7, 2 and 11/spl times/10/sup 13/ p/cm/sup 2/ (equivalent to twice the fluence in high energy protons), and have measured the depletion voltage before and after irradiation using C-V methods. In addition, we have measured the charge collection of minimum ionization on a single strip with a fast amplifier as a function of bias voltage. We compare the depletion voltage deduced from both methods for samples with different initial resistivities.