In bacteria, this system is known as CRISPR (Clustered Regularly Interspaced Palindromic Repeats, see CHESS news item: Adaptive Immune Systems of Bacteria, 2012) and consists of RNA which recognizes and binds the foreign DNA or RNA through an RNA-mediated interference mechanism and a number of Cas (CRISPR-associated) proteins which help to either form the complex or to degrade the foreign DNA. The complex is known as CASCADE (CRISPR-Associated Complex for Antiviral Defense).

In the past, users performing electrochemical experiments at beamlines brought their potentiostats from their home laboratories. Because they are delicate, there is a risk of breakage of their internal components while transporting them, adding delays to users’ research programs if they do break. By having one at CHESS, users no longer need to bring one from their laboratories. There are several advantages of the Bio-Logic model. First, because of its portable design, it can easily be set up at different stations.

The octahedron itself can be composed of smaller particles located at the corners of the octahedron. Such binary structure of large iron oxide spheres of 13 nm diameter enclosing a hexamer of six small 4nm lead sulfide particles is known as an AB₆ binary superlattice.

Currently, the data that is collected at F2 and at F3/G3 (with the Maia detector) is being written directly to this new centralized data storage, and we plan to extend this system to other beamlines and detectors in future cycles. This data is accessible for analysis on the CLASSE compute cluster, and long-term archival storage is provided by an offsite magnetic tape library.

The system was developed in close collaboration with user groups using our XES capability over the last 5 years. The spectrometer name, DAVES, is both an acronym and tribute in memory of a good friend to the x-ray community, Dave Rognlie, who supplied HUBER diffraction equipment in the USA for over 30 years. DAVES – Dual Array Valence Emission Spectrometer - uses the simplest design possible for a multiple-crystal-analyzer, Rowland circle spectrometer, with simultaneous capability for independent measurements of two emission lines from one sample.

The old relay and L.E.D. system has been replaced with a hybrid system that mixes software and relay logic to provide core safety functions along with additional software control, protection and monitoring.

This is the preferred detector worldwide for macromolecular crystallography, because of its large dynamic range, zero background, very small point spread function, and millisecond readout time.

The two particle beams were the hallmark of the successful high-energy physics colliding beam program, but with those experiments finishing in 2008 x-ray production for CHESS became the primary mission of the laboratory. At that point source stability and flexibility became the top accelerator priority, driving the development of top-off injection that keeps the positron current constant at 200 milliamperes as well as a new slow-orbit feedback system that reduced x-ray beam source drifts to fewer than 10 microns.

To accommodate the very high heat load of this new, brighter source, the old swappable A2 monochromators have been retired, and replaced by a dedicated double-bounce diamond system behind a removable white-beam vertical-focus mirror. The front-end has been entirely rebuilt, and is now window-less from CESR all the way to the hutch. The new beamline is extremely versatile, delivering bright monochromatic x-ray beams at any incident energy between 5 keV and 70 keV.

Thanks to a little luck and a lot of clever engineering, the two, newly-installed canted undulators feed G-line without any modification to the G-line optics. This works because the two undulator beams, which are separated by 1 milliradian, fit almost perfectly within the much wider fan of radiation previously produced by the wiggler. With the wiggler installed, G2 and G3 shared the Northern half of the wiggler fan, while G1 used the Southern half.