Bayesian deconvolution as a method for the spectroscopy of X-rays with highly pixelated photon counting detectors

Abstract

The energy deposition spectrum of highly pixelated photon-counting pixel detectors with a semiconductor sensor layer (e.g. silicon) differs significantly from the impinging X-ray spectrum. This is mainly due to Compton scattering, charge sharing, an energy-dependent sensor efficiency, fluorescence photons and back-scattered photons from detector parts. Therefore, the determination of the impinging X-ray spectrum from the measured distribution of the energy deposition in the detector is a non-trivial task. For the deconvolution of the measured distribution into the impinging spectrum, a set of monoenergetic response functions is needed. Those have been calculated with the Monte Carlo simulation framework ROSI, utilizing EGS4 and including all relevant physical processes in the sensor layer.