Simulation and measurements of the internal electric field of a CZT (or CdTe) detector under high X-ray flux for medical imaging

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Abstract
Simulation of room-temperature radiation detector for high X-ray flux application leads to investigate the created space charge. Existing models are based on transport, trapping and subsequent detrapping of charge. Problem is that parameters of these models are difficult to measure and simulation is very sensitive to any variation of these parameters especially for the space-time solution. Our approach is: first we measure the electric field, second we build a model for it. Measuring the electric field provides important information on the distribution and the dynamics of the electric phenomena for a better understanding of the detector behavior under high X-ray flux. Observations show non uniform electric field and a polarization under X-ray irradiation depending on the applied voltage. Experimental measurements and simulations based on charge transport models with trapping effects have also a good correlation.