X-ray fluorescence imaging with pixel detectors

The main goal of this work is to determine the capabilities of the Medipix2 and Timepix devices for imaging in X-ray fluorescence (XRF) analysis. The energy resolution of these devices is not sufficient for identification of characteristic radiation in each pixel. The proposed method of per pixel spectra decomposition overcomes this disadvantage. The method splits into two phases: In the first (calibration) phase the spectroscopic responses of each pixel to the characteristic radiation of the individual elements are measured. In this way, a set of spectra (base vectors) is acquired for each pixel. In the second phase a complex spectrum of unknown sample is measured and then decomposed to spectra of individual elements. If the global elemental composition of the specimen is qualitatively known (or can be estimated) then elements with atomic number difference of 1 can be resolved. The spatial resolution is limited by the diameter of the pinhole aperture.