The CZT Ring-drift detector: A novel concept for hard X-ray detection

We report on experimental and theoretical results obtained with a CdZnTe (CZT) detector with a novel type of read-out scheme: the ring detector. This detector has been tested extensively both in our laboratories and at the HASYLAB synchrotron facility and demonstrated excellent energy resolutions of up to 0.73%, over a wide dynamic range covering 6-662 keV. The key feature in this design is a carefully managed charge transport which eliminates the hole contribution, and optimizes the electron collection. We are developing a theoretical model of this detector, to allow the optimization of the read-out structure as a function of detector dimensions. A comparison between X-ray scans across the detector and model calculations shows that the model already captures all the major detector features, but still leaves a few challenging questions related to CZT surface conductivity. It is clear, however, that the ring- detector concept offers the potential of versatile, high- performance X-ray detectors, with applications in space, nuclear research and medicine.