Stack of Timepix-based detectors with Si, GaAs:Cr and CdTe sensors with optimized thickness for spectral CT

Hybrid pixel detectors based on the Medipix chips have proven themselves as a good tool for spectral X-ray imaging. An important advantage of such detectors is the possibility to use various sensor materials (Si, GaAs:Cr, CdTe etc). Each of these materials has own advantages and disadvantages. The higher Z materials provide the higher photon registration efficiency, but also the greater energy of the fluorescent photons distorting the detector’s energy response. The thickness of the sensor affects the same way: the thicker sensor means the higher photon registration efficiency, but the energy resolution gets worse. At the same time, photons that have passed through the detector without interacting in it can be registered by the next detector. The combination of several detectors with various sensor materials allows increasing the overall photon registration efficiency. In this case, each detector will operate in the optimal energy range. In this work, we consider a system based on three Timepix detectors with sensors made from Si, GaAs:Cr and CdTe. The Monte Carlo simulation was used for the sensors thickness optimization. The possibility and advantages of using such imaging system for spectral CT are demonstrated.

Kozhevnikov, D., & Smolyanskiy, P. (2019). Stack of Timepix-based detectors with Si, GaAs: Cr and CdTe sensors with optimized thickness for spectral CT. Journal of Instrumentation, 14(02), C02010.