Advanced Photon Source
The Advanced Photon Source (APS) at Argonne National Laboratory (in Argonne, Illinois, USA) is a national synchrotron-radiation light source research facility funded by the United States Department of Energy Office of Science. The facility "saw first light" on March 26, 1995. Argonne National Laboratory is managed by UChicago Argonne LLC, which is composed of the University of Chicago and Jacobs Engineering Group.
Using high-brilliance X-ray beams from the APS, members of the international synchrotron-radiation research community conduct forefront basic and applied research in the fields of materials science and biological science; physics and chemistry; environmental, geophysical and planetary science; and innovative X-ray instrumentation. As of 2015[update], APS held the distinction of being the facility at which 21 of the 30 known g-protein coupled receptor protein structures had been solved.[1]
How APS works
Electrons are produced by a hot cathode that is heated to about 1,100 °C (2,000 °F). The electrons are accelerated to relativistic speeds (99.999+% of the speed of light) with an energy of 450 MeV in a linear accelerator.[2] From the linear accelerator, the electrons are injected into the booster synchrotron. Here, the electrons are sent around an oval racetrack of electromagnets, providing further acceleration. Within one-half second, the electrons reach 7 GeV of energy.[3] Upon reaching that energy, the electrons are injected into the storage ring, a 1,104-metre (3,622 ft) circumference ring of more than 1,000 electromagnets.[4]
Once in the storage ring, the electrons produce x-ray beams that are available for use in experimentation. Around the ring are 40 straight sections. One of these sections is used to inject electrons into the ring, and four are dedicated to replenishing the electron energy lost though x-ray emission by using 16 radio-frequency accelerating cavities. The remaining 35 straight sections can be equipped with insertion devices.[5] Insertion devices, arrays of north-south permanent magnets usually called “undulators” or "wigglers", cause the electrons to oscillate and emit light in the invisible part of the electromagnetic spectrum. Due to the relativistic velocities of the electrons, that light is Lorentz-contracted into the x-ray band of the electromagnetic spectrum.[5]
The Experiment Hall surrounds the storage ring and is divided into 35 sectors, each of which has access to x-ray beamlines, one at an insertion device, and the other at a bending magnet.[6] Each sector also corresponds to a lab/office module offering immediate access to the beamline.[7]
Features and improvements
So called "micro-beams" (reduced cross-section, increased energy density) have been implemented in conjunction with rapid detection methods to improve the ability to obtain structure information from the small, weakly diffracting, radiation-sensitive protein crystals characteristic of membrane proteins.[1] By the 2020s, a new storage ring technology is proposed to have been installed at APS (multibend achromat) which should provide increased beam intensity with nanometer-level beam cross-sections.[1]
See also
References
- ^ a b c Liszewski, Kathy (1 October 2015). "Dissecting the Structure of Membrane Proteins". Genetic Engineering & Biotechnology News (paper). 35 (17): 14.(subscription required)
- ^ "Linear Accelerator". Argonne National Laboratory. Retrieved 9 January 2008.
- ^ "The Booster Synchrotron". Argonne National Laboratory. Retrieved 9 January 2008.
- ^ "The Electron Storage Ring". Argonne National Laboratory. Retrieved 9 January 2008.
- ^ a b "Insertion Devices". Argonne National Laboratory. Retrieved 9 January 2008.
- ^ "Experiment Hall & Beamlines". Argonne National Laboratory. Retrieved 9 January 2008.
- ^ "LOMs & Beamlines". Argonne National Laboratory. Retrieved 9 January 2008.
External links
