Performance of microdot detectors of 50-, 100-, and 200-mu m pitches based on the amorphous silicon process

Abstract

Microdot detectors, which are based on the amorphous silicon process and which have square-shaped electrodes and three different anode-to-anode distances of 50, 100, and 200 mum, have been developed for a reliable true two-dimensional (or pixel) device. Their electrical characteristics, such as insensitive regions and spatial resolution, were tested using a collimated X-ray beam as a probe. Our results suggest that the 100-mum pitch appears to be the optimum value both to minimize the defocusing away from the anode dots of the primary electrons and to achieve good spatial resolution (55 mum) and a moderate gas gain (3100).