Quantitative assessment of ohmic-type CdTe sensor response in a photon-counting X-ray imaging detector under continuous 12-49 keV irradiations.

For several years, photon-counting X-ray imaging detectors with cadmium telluride (CdTe) sensors have been used in high-energy synchrotron experiments. While these detectors exhibit excellent detection sensitivity at high energy, concerns remain regarding their performance stability over time under exposure to high-energy X-rays, an issue that can be critical for certain experiments. This study aims to quantitatively assess the response of ohmic-type CdTe sensors under well defined conditions of continuous X-ray irradiation, considering dose rate, photon energy and average absorbed dose throughout the sensor depth. Measurements were performed in a laboratory environment using a dedicated setup with a reliable and reproducible measurement protocol. The results revealed significant irradiation-induced performance variations over time. Notably, a loss of more than 11% in photon counts was observed, even at a relatively low photon flux of 5000 photons s^-1 pixel^-1 at 49 keV. The key contribution of this work is a quantitative characterization of the behavior of CdTe sensors within the 12-49 keV energy range under controlled conditions. These findings provide essential insights for synchrotron experiments operating in this energy range. Furthermore, the proposed measurement protocol offers a reliable method for quantitatively comparing the stability of other high-Z sensor materials against state-of-the-art CdTe technology.