X-ray fluorescence (XRF) is known method for the material elemental composition analysis. Usually, high quality spectroscopic detectors are used for precise elemental analysis, however it is very difficult to obtain information about spatial distribution of elements. To get an image of a spatial distribution of elements contained in the specimen we use the Medipix or TimePix pixel detectors.
In our setup, the tested sample is iluminated by an X-ray tube. The Timepix pixel detector with pinhole aperture is used. Energy resolution of the Timepix device is approx. 3 keV, which is not sufficient for full elemental analysis. If global elemental composition of the specimen is known (or it can be estimated) and if calibration of response of each Medipix pixel to fluorescence spectrum of each of these elements is done, then it is possible to retrieve the distribution of elements in the sample using spectrum decomposition technique.
Medipix2 detects X-rays particles with minimal energy approx. 3keV. That is why it is possible get an image of spatial distribution of elements with atomic number greater than 19 (potasium). It is possible to resolve elements with difference in the atomic number of 1.