Multiple Module Pixellated CdTe Spectroscopic X-Ray Detector

A pixellated CdTe detector system comprising 2×2 detector modules has been developed for high energy spectroscopic X-ray imaging applications and has an active area of 16 cm² . The detector modules are made from the HEXITEC 80×80 ASIC and 1 mm thick CdTe with Al-Schottky contacts. The CdTe has 250 μm pitch pixels with an outer guard ring on the same pitch. The single HEXITEC 80×80 detectors have an average energy resolution (FWHM) of 800 eV at 59.9 keV. Limitations in the multiple module DAQ system mean that the energy resolution of the pixels in the 2×2 detector array is 2.0 keV at 59.9 keV. The spacing between the tiled detector modules is 150 μm which results in an inactive area equivalent to 3 pixels, including the guard ring on the edge of the detectors. The modular detector configuration demonstrates the potential to create large area detector arrays in the future.