A fast X-ray detector using silicon avalanche photodiodes of 64-pixel linear array

Abstract

We have developed a silicon avalanche-photodiode (Si-APD) array detector operated in the linear mode for time-resolved measurements using pulsed synchrotron X-rays. The Si-APD detector had 64 pixels of a linear array, where the pixel size was 100 μm by 200 μm with a 50-μm gap between pixels and a depleted thickness was 10 μm. A nanosecond response of the array detector is extremely valuable for time-resolved X-ray diffraction measurements in the multi-bunch mode operation of a 500M-Hz synchrotron ring. In order to apply the APD detector for the time-resolved diffraction measurements with 2-ns pulse-pair resolving time and a count rate of more than 10 s−1, an ultra fast ASIC has newly been developed for processing a nanosecond-width pulse from each pixel of the Si-APD array. A prototype system had a 10-ns time resolution and a high count-rate of more than 107 s−1/pixel in the first test measurement using synchrotron X-ray beam.