High Brightness Beam for Microcrystallography at GM/CA@APS

GM/CA is a world leader in the development of microcrystallography capabilities for biological macromolecules. The combination of the GM/CA-developed quad-mini-beam collimator and advanced rastering and vector collect software tools have revolutionized microcrystallography. Recently, beamline 23ID-B was reconfigured by shifting the focusing optics 3.8 m downstream. This significantly increased the source demagnification and led to a 4-fold increase in the 5- and 10-micron beam intensity. Beamline 23ID-D is also being upgraded. A Pilatus3-6M with a 1.0 mm thick X-ray sensor was commissioned in January 2014 allowing shutterless data collection with high S/N. The detector specifications include 100 Hz frame rate, 10 MHz/pixel count rate, and high X-ray efficiency. The beamline optics and endstation are also being upgraded to provide a high intensity beam whose size can be variable rapidly in the range of 1 - 20 micron, a new air bearing goniometer with a sphere-of-confusion (SOC) of ~100 nm, a miniature sample XYZ stage that allows centering and scanning of a micron-sized crystal, and a new on-axis-visualization system that provides high resolution optical images of sample crystals. Plans are being developed to upgrade the Advance Photon Source storage ring with a Multi-Bend Achromat lattice. The source properties will be dramatically improved primarily by reducing the horizontal source size to be comparable to the vertical source size, resulting in a 2-3 orders of magnitude increase in source brightness. Both beamlines will be significantly improved by the source upgrade. Moreover the new microfocusing optics for 23ID-D will fully exploit the new source and could deliver a 500 nm (FWHM) beam with >2e13 photons/sec. This unprecedented flux density will provide new opportunities and challenges, and allow the study some of the most important problems in biology. Details of these developments will be presented.

Materials behavior under Fast Compression or Decompression

Phase transformation pathways are strongly influenced by the time dependence of the driving mechanism (compression, thermal transfer, strain, irradiation, etc). While thermal rate has been widely used for centuries for enhancing materials properties such as hardened steels or metallic glasses through rapid cooling, the application of compression rate is relatively new. Yet it drives rich new physics, novel chemistry, exceptional energy materials, and new routes of materials synthesis, and has become an important impetus in studying materials metastability, phase growth, and transition kinetics. In this talk, we will outline recently developed capabilities at HPCAT at the Advanced Photon Source for studying materials behavior under fast compression or decompression, including both single event loading or unloading and multiple, repetitive ramping events. A few recent studies will be highlighted. For example, a compression rate of 17 TPa per second has been reached in a piezo-driven diamond anvil cell; fast compression experiments significantly improve the precision in thermal equation of state determinations; the feasibility of controlled formation of metastable phases of Si and Ge has been demonstrated under controlled decompression rate; the phase transition kinetics of B1-B2 transitions in NaCl and KCl have been studied under various compression and decompression rates.

Adventures in Phasing: Flavivirus NS1 solved by low resolution native S-SAD

We used native sulfur-SAD phasing to determine a novel structure of significant health importance, the flaviviruses non-structural protein 1 (NS1). Flaviviruses cause many diseases including dengue and West Nile fever. NS1 functions in both genome replication and immune system evasion. Full length, glycosylated NS1 was expressed in insect cells and crystallized. Due to difficulties with protein expression SeMet phasing was not practical, and we embarked on an effort to use sulfur-SAD phasing. To optimize the probability of observing the estimated 1.5% S-anomalous signal, we used inverse beam protocol at 7.1 keV with 5⁰ wedges and 0.5⁰ oscillations. Crystals typically diffracted to ~3.0 Å. Pairwise comparisons of anomalous correlation coefficient (AnomCC) and Rmerge in the highest intensity (low resolution) bins were used to decide which crystals to include in the final data set. Crystals which when compared to other crystals consistently had AnomCC < 0, or Rmerge > 7.5% in the low resolution bin were excluded. Data from 18 of 28 crystals were combined to generate a data set with ~100 fold anomalous multiplicity. The final data set was of high quality by I/σI and CC1/2 metrics with a positive AnomCC to ~5.4 Å. Sulfur sites were found with SHELXD using data to 5.2 Å. Phases calculated to 4.5 Å by SHELXE and extended to 3.0 Å with DM were of sufficient quality to autobuild ~75% of the final model. The NS1 structure was complete with the exception of one 20-residue internal loop, and glycosylation was observed at expected sites. Although Rmerge values were high for the combined data (30% overall, 9% low-res, 900% hi-res), model building and refinement proceeded smoothly, supporting the notion that Rmerge is a poor indicator of data quality for purposes of refinement and may also be a poor indicator for purposes of phasing. The effects of data multiplicity and resolution on S-site determination, phase calculation and phase extension were investigated.

Current and future detector developments at the Swiss Light Source

The detector group of the Swiss Light Source (SLS) at the Paul Scherrer Institut (PSI) has a long history of x-ray detector developments for synchrotrons. Initially these detectors were all single photon counting systems. In the last years the focus at PSI was moving towards charge integrating systems mainly driven by the detector needs for the upcoming XFELs. Charge integrating systems however also solve some of the problems of single photon counting systems. Charge integrating systems have an almost infinite linear count rate capability, allow systems with smallest pixel sizes and for low photon energies. In this presentation we give an overview of the detector developments at PSI and focus on Jungfrau, Mönch and Eiger. Eiger is a single photon counting system specifically developed for high frame rates. It has a 75 micron pixel size and can run at frame rates up to 24 kHz. A 9M Eiger detector will be installed in a few months at the cSAXS beamline of the SLS. Jungfrau uses the same sensor as Eiger (about 4cm x 8 cm with a pixel size of 75 microns). It has a charge integrating architecture with dynamic gain switching to achieve a dynamic range of 10^4 photons (at 12 keV). With a frame rate of up to 2 kHz Jungfrau is currently being developed for applications at both XFELs and synchrotrons. 16M Jungfrau detectors are foreseen at the SwissFEL. Mönch is currently a research project. A first prototype with 160x160 pixels and a pixel size of 25 microns was designed and is currently characterised. It offers the smallest pixel size of current hybrid pixel detectors and also has a very low noise allowing hybrid pixel detectors to be used down to about 400eV. We present measurement results for Jungfrau, Mönch and Eiger and give an outlook on future possible systems.

Integration and first data with a Pilatus3 6M at APS beamline 23ID-D

GM/CA@APS operates two insertion-device beamlines, 23ID-B and 23ID-D, and one bending magnet beamline, 23BM-B, in sector 23 of the Advanced Photon Source. We recently integrated a Pilatus3 6M detector - a new generation of large sensitive area detectors based on pixel array detector technology and marketed by Dectris. The sensitive area of the device is 423.6 mm × 434.6 mm. The Pilatus3 features the newly implemented re-triggering mechanism that increases the count-rate capabilities by almost an order of magnitude compared to previous generation Pilatus detectors. The detector installed on beamline 23ID-D is the first Pilatus3 6M with a 1000-micron thick sensor, offering higher efficiency at energies above 12 keV. The fast read-out (0.95 ms) and high speed (up to 100 Hz) of the detector allow shutterless data collection. The detector has been fully integrated into the JBluIce user interface and data processing pipeline at GM/CA. Systematic studies with protein crystals were carried out in order to optimize data collection parameters. Overall data collection speed (frame rate), oscillation width per frame, spindle axis speed, and re-triggering have been studied. Different sets of optimal parameters have been established for crystallographic data collection and for crystal screening with the raster feature (grid scanning). The results of these studies and of performance measurements will be presented. This project and GM/CA @ APS are supported by the National Institute of General Medical Sciences and Cancer Institute of NIH.

Remote Access Capabilities at the GM/CA Beamlines at the APS

The GM/CA facility consists of two undulator source beamlines and a bending magnet beamline at the Advanced Photon Source (APS). Access to the operation of these beamlines is accomplished through visits by investigators who are either on-site, remote or a combination of the two. In all modes of access, user operations are controlled by the experimenter. The control and capabilities of the GM/CA beamlines are identical for remote and on-site users. Remote access to the beamlines is through NX or Teamviewer to local computers [1]. Once communication has been established, experienced GM/CA experimenters are greeted by our familiar JBluIce, the graphical user interface/control program[2] responsible for all operations from sample handling through data collection and reduction. Although investigators always see a familiar interface, both software and hardware on the beamlines are continually improving. Recent hardware upgrades include a shift of the optical focusing mirrors on the ID-B beamline closer to the sample to provide a significant increase in flux, and installation of a new Pilatus3 6M detector on ID-D, the second undulator beamline. The JBluIce program has incorporated new detector controls for shutterless operation while continuing to expand the features of rastering, vector (helical) data collection, strategy tools and data analysis. These tools have been essential to investigators working on membrane crystal samples, e.g. GPCRs, as well as for samples that decay quickly or require data to be collected from multiple crystals. The presentation will provide an overview of beamline remote control as well as an update of the equipment that it operates at GM/CA.