F1 Beamline

MacCHESS – macromolecular crystallography and BioSAXS

F1 Beamline Specifications
Source: 24-pole wiggler
Optics: White beam collimating mirror, horizontally focusing monochromator using single bent triangular Si(111) crystal, vertically focusing Rh-coated Si mirror
Energy: 12.68 keV (0.98 Å), fixed
Detector: Dectris Pilatus 6M
Beam size at sample: 100 or 20 μm*
Photons/sec through 100 µm collimator: 5.5 x 109 (at 200 mA beam current)

*Other sizes available on request

F1 is fully equipped for monochromatic macromolecular crystallography (MX). During the annual BioSAXS Essentials workshop, it is temporarily reconfigured for small-angle scattering (BioSAXS), so that two stations are available for the workshop. Crystallographic equipment includes a single-axis goniostat, Oxford Cryosystems cryocooler, high-resolution crystal viewing system with autocentering as well as click-to-center software, ALS-style BAM-1 crystal automounter which accepts multiple types of puck, and a Dectris Pilatus 6M. Beam sizes of 100 µm and 20 µm are routinely available. Crystal-detector distances of about 75-1500 mm. are possible. The X-ray energy of 12.68 keV (0.98 Å) is suitable for monochromatic data collection from most macromolecular crystals, and is just above the Se absorption edge, so that a good anomalous signal for SAD phasing can be obtained from crystals containing selenomethionine (SeMet). Special illumination which enhances sample visibility by using intrinsic protein fluorescence is installed. The ADX GUI controls all aspects of data collection, including crystal annealing. An innovative confocal optical system for viewing crystals in 3D is under development, and available to selected users.

The BioSAXS setup includes an evacuated flight path, dual Pilatus 100-K detectors for recording SAXS/WAXS data, a computerized flow control system including custom sample cells, the Robocon GUI for experiment control, and RAW software for data analysis. A q range of 0.007 to 0.7 Å-1 is accessible.

BSL-2 biohazards, such as some viruses, are accepted. Mail-in and remote data collection (for MX) modes are available, and a high level of support is provided for all users.

F1 equipment
Crystallography and BioSAXS equipment. Beam enters from the right. For MX, the rotation stage, cryocooler, crystal-viewing telescope, and automounter surround the crystal at right center, and the detector is at the left. For BioSAXS, a liquid sample cell with automated flow control replaces the goniometer, and an evacuated flight tube between sample and detector (Pilatus 100K instead of Q-270) is installed. Photo is from an early test; current setup has two detectors and better support for the flight tube.