Timepix3 detector: Performance of thick CdTe sensors for spectral X-ray imaging in industrial applications

This study presents the initial imaging performance results of a 5 mm thick CdTe Timepix3 ASIC for high-energy photon detection and imaging, continuation of previous work done with a 2 mm CZT sensor, which demonstrated enhanced material contrast by using sub-pixel imaging and spectroscopically-enhanced imaging. The increased sensor thickness has a few immediate implications. On one hand, it increases radiation attenuation and thus radiation detection efficiency. On the other hand, a thicker sensible volume increases charge-sharing between neighboring pixels, which at the same time can potentially increase spatial resolution through sub-pixel imaging. Yet, by leveraging the ASIC's spectral analysis capabilities, such as Time-over-Threshold (ToT) and Time-of-Arrival (ToA), event information can be used to improve the image formation process beyond untreated datasets, by using techniques such as event clustering. Additional material calibration measurements allow the use of energy-weighted imaging that increase the Contrast-to-Noise ratio of specific materials, allowing for material highlighting, separation and identification in real-life samples. The 5 mm thickness, was subjected to a general device characterization. While the use of detectors with sensor thicknesses beyond 2 mm is rare, achieving good imaging performance with thick detectors can open new application possibilities e.g. non-destructive testing in production sectors, radiotherapy or nuclear medicine. Thus, this work highlights the potential of the 5 mm CdTe Timepix3 detector in material visibility enhancement, showcasing its potential in a range of industrial applications for Spectroscopic Photon Counting Detectors SPCDs.