Hybrid pixel detector for time resolved X-ray diffraction experiments at synchrotron sources

This paper presents the test results of a prototype asynchronous hybrid pixel amplifier array chip, the PAC2, which is primarily intended for time resolved X-ray diffraction experiments, where the ability to provide time and spatial resolution in high fluxes is particularly important. The chip consists of an 8 × 8 array of 300 × 300 μm2 pixels, fabricated in 1.5 μm CMOS technology. Individual PAC2 amplifiers show an equivalent noise charge performance of less than 211 electrons r.m.s., with pixel to pixel comparator offset variations of 110 electrons r.m.s. The lower energy limit for X-ray detection can be as low as 4 keV, and results are presented from a prototype PAC2/silicon detector set-up which demonstrate close to 100% detection efficiency for 5.9 keV 55Fe X-rays.