Modeling of the response function of CdTe detectors for a hard X-ray synthetic diagnostic

•A realistic response function is modeled for the CdTe detectors used in a hard X-ray diagnostic of the TCV tokamak.•The characteristics of the detector observed in the measurement of multiple radioactive. sources are considered in the modeling.•The measured energy spectra of radioactive sources can be correctly reconstructed using the new response function.•The response function is applied to a hard X-ray synthetic diagnostic for the study of energetic electrons. The response function of CdTe detectors used in a hard X-ray spectrometer system (HXRS) on the TCV tokamak fusion experiment is modeled based on the measured energy spectra from multiple gamma-ray sources. The response function consists of an asymmetric Gaussian photopeak, an exponentially inclined shelf structure below the photopeak, and CdTe escape peaks. It is demonstrated that the measured energy spectra of radioactive sources can be correctly reconstructed using this response function. This model is applied to a hard X-ray synthetic diagnostic used to convert a modeled electron distribution function to a measured hard X-ray signal, for the study of energetic electrons in the TCV tokamak.