The other "SURF": Summer
Undergraduate Research Fellowship program
SURF III Home Page
SURF III Upgrade
The first stored beam and production of synchrotron radiation from SURF occurred at 11:10 AM 17 Dec 98. The initial electron beam was an unknown current (probably on the order of a few mA) of 100 MeV electrons. Later in the day that beam was ramped up to 380 MeV. The commissioning process will continue and the maximum energy, beam current, and beam lifetime will be improved.
The web page describing SURF II and the science experiments being conducted is still available.
See the construction of the SURF magnet.
See the assembly of the SURF lower yoke.
Take a pictorial tour of the disassembly of SURF II.
Project OverviewThe Electron and Optical Physics Division of the Physics Laboratory has operated the Synchrotron Ultraviolet Radiation Facilty at the National Institute of Standards and Technology (NIST) for over 30 years. Initially operated in a parasitic mode at the NIST electron synchrotron, the facility was converted into the SURF II electron storage ring in 1974. SURF II has been the United States national standard of irradiance in the vacuum ultraviolet spectral region as well as a world-class research facility for many diverse fields of investigation that require high-intensity continuum radiation from the soft x-ray to the infrared spectral regions.
The radiometric accuracy of SURF II as an irradiance standard was limited by the uniformity of the magnetic field encountered by the electrons as they traversed their orbit. Variations of up to 0.5% limited the knowledge of the local bending radius at any tangent point and restricted the accuracy of the irradiance calculations. Additionally, the performance of the magnet structure is no longer state-of-the-art. Modern magnetic materials have better performance characteristics than materials available in the 1940's, when the electron synchrotron magnet used by SURF II was built, and the conversion of SURF from a 60 Hz AC synchrotron to a DC storage ring changed the desired characteristics of the magnet material and the shape of the poles so that the original design choices are no longer the most appropriate.
Two improve the radiometric accuracy of SURF, an entirely new magnetic structure was designed and is being built. The general contractor for the project is PSL Engineering and Instrumentation. The azimuthal uniformity of the SURF magnetic field will be improved by a factor of 50, allowing irradiance calculations to be made with much higher accuracy than SURF II could achieve. As an additional benefit, the use of improved magnet material, a smaller air gap between the poles, and a higher electrical current (new magnet windings will be installed) will increase the magnetic field strength at the electron orbit, allowing SURF to store electrons at energies as high as 400 MeV, compared to 300 MeV for SURF II. The higher electron energy will extend the usable range of radiation from SURF to shorter wavelengths, enabling experiments in the "water window" from 2.3 nm to 4.4 nm.
ImprovementsThe primary purpose of the upgrade from SURF II to SURF is to improve the radiometric accuracy of SURF as an irradiance standard by improving the magnetic field uniformity. The upgrade project offers an excellent opportunity to make other improvements and modifications to the facility. The following list outlines the major changes being made and the improvements they offer.
NIST staff involved in the upgrade (left to right): Bob Madden, Mitch Furst,
Lanny Hughey, Rob Vest, Andrew Hamilton, and Rossie Graves. Not shown is
Al Raptakes (who's taking the picture). The crew is standing in front of the
partially disassembled SURF II storage ring - only the backlegs and lower yoke
Inquiries or comments: Rob Vest, SURF III, NIST
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