Position Sensing in CdZnTe Semiconductor Detectors via Proximity Charge Sensing Pixels

Abstract

Proximity charge sensing is a novel technique used in the field of radiation detection. This research examines the simulation of a pixelated anode proximity charge-sensing device on CZT semiconductors to evaluate the potential performance of the proximity sensing technique on room-temperature detector materials for imaging purposes. The weighting potentials (WPs), of proximity-sensing and directly deposited electrode pixelated designs, were generated using ANSYS Maxwell, and the best design will be considered for the implementation step in the future. The simulation investigated two features of the proximity design, pixel size and pixel pitch. Three different pixel sizes were used in the simulation designs, 0.5 × 0.5 mm2, 1.0 × 1.0 mm2, and 2.0 × 2.0 mm2. The 0.5 × 0.5 mm2 pixel size had the best WP profile, where the generated signal for one radiation energy did not depend on the interaction location. Pixel pitch was examined using the same pixel size, 1.0 × 1.0 mm2, and varying the pixel pitch from 2.0 mm, 3.0 mm up to 4.0 mm. The results showed that as the pixel pitch increases, the signal crosstalk (charge sharing between pixels) decreases. However, as the pixel pitch increases, the spatial resolution of the imaging system decreases, making it difficult to observe objects smaller in diameter than the pixel pitch. Additionally, proximity charge sensing designs showed better performance in terms of signal crosstalk for the same pixel size and pixel pitch in comparison with directly deposited designs.