Producing brilliant x-ray beams at the APS begins with electrons emitted from a cathode heated to ~1100° C. The electrons are accelerated by high-voltage alternating electric fields in a linear accelerator (linac; photo below). Selective phasing of the electric field accelerates the electrons to 450 million volts (MeV). At 450 MeV, the electrons are relativistic: they are traveling at >99.999% of the speed of light, which is 299,792,458 meters/ second (186,000 miles/second).

Synchrotron storage rings optimized for insertion devices (photo below) are called "third-generation" light sources. Some, like the Advanced Light Source in California and the SuperACO in France, provide radiation in the ultraviolet/soft x-ray part of the spectrum. The 7-GeV APS and its sister facilities, the 6-GeV European Synchrotron Radiation Facility in France, and the Super Photon Ring 8-GeV (SPring-8) in Japan, can produce a range of x-rays up to those of the hard (highly penetrating) variety because of higher machine energies.

In designing the experiment hall, the APS benefited from the experiences of researchers who had carried out experiments at other synchrotron facilities. One lesson learned was the need for adequate user laboratory and office space. The APS User Organization opted for laboratory/office modules (or LOMs) and were clear in their desire that the modules be located as close as possible to beamlines. As shown in the diagram below, LOMs are adjacent to the experiment hall, a short walk from each beamline.

User beamlines comprise crystal and/or mirror optics designed to tailor the photon beam for specific types of experiments. These optics select out about one part per million from the energies (or wavelengths) that are carried by the insertion device beam and pass that energy down the beamline to a lead, radiation-proof experiment station that contains the sample under investigation; additional optics that may be needed to analyze and characterize the scattering, absorption, or imaging process; and detectors to collect data from the interaction of x-ray beam and sample.

This concludes your introduction to the APS! For information about becoming a user and obtaining x-ray beam time at the APS, start here.

ntrepid has a highly scalable torus network, as well as a high-performance collective network that minimizes the bottlenecks common in simulations on large, parallel computers. Intrepid uses less power per teraflop than systems built around commodity microprocessors, resulting in greater energy efficiency and reduced operating costs. Blue Gene applications use common languages and standards-based MPI communications tools, so a wide range of science and engineering applications are straightforward to port, including those used by the computational science community for cutting-edge research in chemistry, combustion, astrophysics, genetics, materials science and turbulence.

Intrepid's Blue Gene/P system consists of

• 40 racks
• 1024 nodes per rack
• 850 MHz quad-core processor and 2GB RAM per node
• 640 I/O nodes
• 88 GB/s, 7.6PB Storage

For a total of 164K cores, 80 terabytes of RAM, and a peak performance of 557 teraflops.