Array of avalanche photodiodes as a position-sensitive X-ray detector

Two types of the silicon avalanche photodiode (Si-APD) array detector have been developed for synchrotron X-ray experiments on nuclear resonant scattering. A 16×2 array of 3×5 mm2 pixels (thickness: 0.15 mm) is proposed for large solid angle measurements of the nuclear resonant inelastic scattering on 57Fe (nuclear resonant level: 14.4 keV). A 4×2 array of 0.5×1 mm2 pixels (thickness: 0.05 mm) is proposed for a 0.5-ns time resolution in measurements of the microscopic Mössbauer spectroscopy. These APD devices have a transmission structure without a thick dead layer. They can be mounted in a stack inside a detector to increase the efficiency for X-rays. The results of the detection efficiency and the timing performance, tested by 14.4-keV X-rays are described. With a proper readout system for each pixel, an array of Si-APDs can used as a new position-sensitive detector, for which one pixel has a very high count-rate capacity of up to 108 s−1.