Characterisation of spectral performance of pixellated X-ray imaging detectors in a microscopy setup

In order to achieve energy resolved X-ray imaging with small pixel resolution, physical processes in the detector material such as fluorescence and charge sharing must be considered. This paper presents characterisation measurements performed with an X-ray microscopy setup for energy resolved imaging. The microscopy setup consists of a nanofocus X-ray source capable of 160 kV anode voltage, ESRF-type collimating slits and Medipix2 detectors. The detector systems developed in the Medipix collaboration are capable of energy resolved imaging. The measurements were performed by scanning an energy window through the spectrum. In this paper we have considered detectors made of Si, GaAs and CdTe for use in the microscopy setup. Both measurements and theoretical simulations are considered. For high X-ray energies, it is essential to consider fluorescence from the shielding and Compton scattering in silicon detectors.