64-Pixel linear-array Si-APD detector for X-ray time-resolved experiments

We have developed a silicon avalanche-photodiode (Si-APD) linear array detector to be used for time-resolved measurements in pulsed synchrotron X-ray experiments. The Si-APD linear array consists of 64 pixels 100×200 μm2, with a pixel pitch of 150 μm and a depletion depth of 10 μm. The nanosecond response and high counting rate of the Si-APD are very valuable for time-resolved X-ray diffraction experiments using pulsed synchrotron radiation. A detector system that can resolve successive X-ray pulses within a short interval of 2 ns would be very efficient for recording the intensity and position of X-ray diffraction patterns within a nanosecond period. A prototype detector system equipped with an ultrafast application-specific integrated circuit, field-programmable gate arrays and network processor boards was fabricated. It allowed a high count-rate of >107 cps per channel with a synchrotron X-ray beam; however, the time resolution was limited to 10 ns. The detector successfully recorded small-angle X-ray scattering by scanning the detector position.