Pixel-pixel interactions in square array CdZnTe detector

Summary form only received as follows: Pixelated CdZnTe radiation detectors have in recent years come under scrutiny by a large number of investigators. Such detectors present inter-pixel phenomena not seen in conventional scintillation detectors. These must be addressed in order to preserve sensitivity comparable to scintillators. The phenomena include Compton scattering, charge diffusion, and fluorescent X-ray production. These phenomena can produce simultaneous signals in two or more pixels. None of the signals alone represents full charge collection. If all the incident gamma energy is deposited in the detector, the amplitudes should sum to a value analogous to the photopeak energy. Simultaneous signals from adjacent pixels were measured as a function of position of a tightly collimated beam. The ⁵⁷Co source was moved along a line between the centers of two pixels. A programmable digital oscilloscope, controlled by a PC, recorded events from the pixels. A three-dimensional plot was constructed with the first pixel plotted on the x-axis, the second on the y-axis, and frequency on the z-axis. Results are presented that quantify these effects and their impact on energy resolution. Further, the authors show a significant number of events that are divided between the pixels to be recoverable, with a measurable effect on detector sensitivity