Application of a directly exposed self-scanning photodiode array as a linear position sensitive detector in a small-angle x-ray scattering instrument

Abstract

A linear position sensitive small-angle x-ray detector has been developed which utilizes a directly exposed self-scanning photodiode array cooled to liquid nitrogen temperature to reduce fixed pattern noise. Direct exposure of the array improves the overall sensitivity to 8 keV photons by an order of magnitude over photoconversion techniques. With this improvement in sensitivity, the photodiode array has been effectively used to detect x rays from weakly scattering biological molecules in solution. The slit-like geometry of the photodector elements ideally matches that of a Kratky collimator employed with a low-flux x-ray source to enhance greatly the data collection rate. The detective quantum efficiency and stability of the detector have been determined while taking small-angle scattering measurements of proteins and the results are quantitatively applied to characterize the performance of the instrument.