X-ray fluorescence imaging with the Medipix2 single-photon counting detector

Material-resolved X-ray imaging or colour X-ray imaging is of a great interest for many applications ranging from physics, industry to medicine and biology. X-ray fluorescence offers a method for producing such images if the energies and positions of origin of the fluorescent photons can be adequately resolved. This paper describes application of the Medipix2 single photon counting imaging detector (256×256 pixels each of 55×55μm² size) for this purpose. The basics of the method are explained including details of the energy calibration of all 65k individual pixels. The effect of charge sharing is discussed and a method for its characterisation based on numerical calculation presented. The charge sharing calculation is then used to generate the Medipix2 detector response matrix, which is subsequently used for analysis of measured spectra in detector pixels.