Development of a CCD Array Detector for combined XRD/XRF applications

摘要

This project is based on the design and testing of a CCD (charge coupled device) based detector to be used for the simultaneous collection of x-ray diffraction (XRD) and x-ray fluorescence (XRF) data from powdered rock samples. The detector designed for this project uses four e2v technologies CCD 30-11 (FI, AIMO) devices tiled in a curved geometry to allow the centre of each of the four CCDs to be exactly 120 mm from the sample. The CCDs are operated in single photon counting mode which allows the detector to simultaneously determine the spatial position of diffracted x-rays as well as resolve the energy of characteristic x-rays fluoresced from the sample. Energy discrimination is then used to reveal the XRD data and radial integration is performed on the four CCD images to extract the "2θ vs. intensity" spectrum. The project also involves the use of a high brightness x-ray micro-source from Bede Scientific Instruments, used to deliver a focused beam of low divergent x-rays to the sample. Collimation and monochromation are also introduced into the system to produce a 93% monochromatic beam of CuKa x-rays, delivered to the powder sample through a 50 μm spot. Details into the design of the CCD array are discussed as well as results presented from various samples.