Photon-counting energy-resolving CdTe detectors for high-flux x-ray imaging

Developments in room temperature cadmium telluride (CdTe) based solid state imaging arrays for energy-resolved single photon counting in x-ray imaging are discussed. We have designed and constructed a CdTe imaging array, 3 mm thick with a 16 × 16 grid of electrical contacts interconnected to a 256 channel ASIC, with a counting range up to 2 × 10⁷ counts per second per mm². Cycling between high and low flux generates measurements which are reproducible within the limits of counting statistics, with a response time less than 1 ms. Long-term stability is determined by measuring flood images repeatedly over time. Long exposure to uniform high or low flux does not affect the temporal response, indicating that no polarization is detected within the statistical error of the measurements.