Macromolecular Crystallography (MX) Core

The GM/CA Macromolecular Crystallography (MX) Core has three main goals. We will provide a modern, powerful environment for sample screening, fine sample examination via rastering, and data collection in tunable, fixed-energy modes for single- or multi-crystal samples. GM/CA will create an intuitive, sophisticated, biologist-friendly user interface for beamline control and data processing and analysis for both on-site and remote users. We will implement beamline and software improvements to provide new capabilities to take advantage of the upgraded APS source and our rebuilt beamlines. GM/CA Group Leader Dr. Robert Fischetti leads the MX Core, Dr. Nagarajan Venugopalan (Beamline Development Section Lead) leads our beamlines upgrade and maintenance, and Dr. Sergey Stepanov (Controls Section Lead) leads the computing and networking effort. Beamlines 23-ID-B and 23-ID-D were rebuilt with state-of-the-art focusing optics and instruments and, coupled with new software controls, provide enhanced capabilities for diffraction experiments. Users will tailor the beam properties to match the scientific needs of their challenging biomedical problems. They will be able to rapidly and reliably select a beam size between 1 and 50 µm over an energy range of 5 – 35 keV (2.48 to 0.35 Å). The beam will be more than 100-fold brighter than before the upgrade. The high-stability endstations will include micro- focusing compound-refractive-lens (CRL) optics, high-precision goniometry capable of rapidly scanning sample mounts with many micro-crystals, high-capacity sample automounters (288 pins), and sample microscopes for visualizing and centering microcrystals. High-speed Eiger pixel-array detectors will support multiple data collection modes at up to 560 Hz (frames per second). GM/CA will provide powerful, user-friendly control software that supports multiple data collection modes such as rastering for diffraction centering, vector-collect to mitigate radiation damage, as well as automated data collection. A data analysis pipeline will automatically process data as they are collected. Beam time will be awarded based on peer-reviewed applications through the APS General User Program. We will support both cryo-cooled and room-temperature samples, and fixed-target and viscous-injector jet modes of serial crystallography. We will continue a multi-tiered maintenance program to anticipate problems ahead of failures and provide full beamline capabilities to users for all scheduled beam time.