Silicon-based photon counting X-ray detector for synchrotron applications

Abstract

We have built the second version of a Large Area Detector (LAD) with a 500 μm thick pixellated silicon detector that is bump-bonded to seven readout application-specific integrated-circuits, (ASICs) each with 64×64 pixels. The detector module has 448×64 pixels, each of 150 μm×150 μm with uniform pixel size and no dead regions. The whole module (67.2 mm×9.6 mm) of photon counting pixels can be activated to readout X-rays with low observed pixel to pixel crosstalk and a high counting rate. Each pixel on the ASIC has a novel 5-bit energy adjustment that is optimised automatically by a Labview-based routine. This cures the observed pixel non-uniformity problem of the earlier design. The detector is sensitive to X-rays from 8 to 25 keV with a programmable energy threshold. A National Instruments based readout system has been built which has been up-graded to a Xilinx FPGA system allowing 1000 frames/s to be acquired from the system. This hardware is controlled with a Labview GUI to program different runs and to display images and spectra. The system can be expanded in a modular fashion to cover 300 mm×300 mm for high-frame-rate protein-diffraction studies at third generation synchrotrons or for other X-ray imaging applications.