Single photon counting pixel detectors for synchrotron radiation experiments

Abstract

At the Paul Scherrer Institute PSI an X-ray single photon counting pixel detector (PILATUS) based on the hybrid-pixel detector technology was developed in collaboration with SPring-8. The detection element is a 320 or 450μm thick silicon sensor forming pixelated pn-diodes with a pitch of 172μm×172μm. An array of 2×8 custom CMOS readout chips are indium bump-bonded to the sensor, which leads to 33.5mm×83.8mm detective area. Each pixel contains a charge-sensitive amplifier, a single level discriminator and a 20bit counter. This design realizes a high dynamic range, short readout time of less than 3ms, a high framing rate of over 200 images per second and an excellent point-spread function. The maximum counting rate achieves more than 2×106X-rays/s/pixel.