High-Speed High-Sensitivity Detector for X-ray Micro-Crystallography at GM/CA@APS

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Project Summary GM/CA @ APS operates two highly successful undulator beamlines as a national user facility for macromolecular crystallography at the Advanced Photon Source (APS). The GM/CA group develops and operates world-leading beamlines in micro-crystallography, offering user-selectable “min-beam” sizes down to 5 m for all samples. Giving users the ability to change beam size rapidly, reliably, and on-demand without staff involvement to optimize the beam size for a given project has led to a sweeping change in experimental practice. The hardware for micro-crystallography is coupled with sophisticated software tools in the JBluIce user interface. Essential tools include rastering to find micro- crystals in complex mounts or to identify the best diffracting regions of larger inhomogeneous samples, helical data collection to distribute dose along rod-shaped crystals and serial data collection from viscous jets or fixed targets. Consequently, the GM/CA beamlines are oversubscribed due to the high demand by a growing number of investigators with challenging NIH-funded structural projects. We are about to embark on an exciting new phase. Our vision is to provide the highest resolution data achievable from challenging problems in structural biology that tend to yield tiny, weakly diffracting crystals. The APS will shut down in April of 2023. The storage ring will be upgraded (APS-U) with a 4th generation multi-bend achromat storage ring, increasing the X-ray brightness by two to three orders of magnitude depending on the X-ray energy. In preparation for the APS-U start-up in April 2024, new focusing optics were installed on 23ID-D. The new mirrors will focus the APS-U source to a beam as small as ~5-microns, and new Compound Refractive Lenses will provide an intense ~1-micron beam. Combining the APS-U source and the new optics is a game-changing opportunity for structural biology. However, beamline 23ID-D has a Pilatus3 6M detector that will be ten years old when the APS-U starts up and must be replaced. To realize our vision, we propose to purchase an Eiger2 XE 16M CdTe detector from Dectris, AG, a next-generation high-speed, high count rate detector with high quantum efficiency for the detection of X-rays with energies from 6 – 35 keV.