SPAN: a novel high-speed high-resolution position readout

The concept for the 2D position-readout device for the SPAN photon-counting detector is presented with attention to the count rates, spatial resolution, and charge-measurement precision. The electrodes which are deposited on the planar substrate result from charge division induced by a charge cloud, the centroid position of which is encoded by the ratio of charge magnitudes. The SPAN electrode design is analyzed and theorized to permit 1000 x 1000-pixel resolution at 1 MHz. The SPAN spiral-anode six-electrode design is compared to the Vernier-anode twelve-electrode structure for encoding 2D position, and digital precision is analyzed at count rates up to 1 MHz. The SPAN readout affords resolution levels of up to 1/1000 across the entire active area at 8-bit digitization.