Performance of silicon trigger counters in the Megarad range

The response of PIN diodes and of novel transistor-diode pixel counters of the DEPMOS type, capable of signal storage, to high radiation doses was studied by means of 10 MeV proton beams scattered from gold foils. The leakage current showed a more than proportional increase with increasing dose and an exponential dependence on temperature. The cooled PIN diodes remained operational at the highest dose of 17.6 Mrad. As specific radiation effects of the DEPMOS counter, incorporating a MOS transistor structure on a fully depleted bulk of 280- mu m-thickness, shifts were observed of the transmission characteristics and a decrease of the acceptance period of the internal gate which allows for nondestructive read-out. Annealing at room temperature was studied for both detector types.<
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