January 23, 2004  


Illuminating Facts about SPEAR3, its Predecessors and Laboratory

By Heather Rock Woods

• SPEAR3 is built within the same curved walls of the original SPEAR machine. Built in 1972 for SLAC’s particle physics program, and upgraded to SPEAR2 in 1974, it yielded two Nobel prizes in particle physics (Burton Richter’s charm quark and Martin Perl’s tau lepton).

• During the upgrade and rebuild, SPEAR2 was almost completely dismantled (including the floor) to make way for its successor.

• The scientific user community had to wait a mere 11 months from when SPEAR2 was shut off to when SPEAR3 comes on-line March 2004, a remarkably speedy schedule for such a complex and comprehensive rebuild of an accelerator.

• Thirty years ago, SSRL was the first laboratory in the world to use storage ring based synchrotron x-rays for studying matter at atomic and molecular scales. SSRL was also among the first to operate as a user facility, offering beam time to a broad user community of scientists from academic, industry and government labs on a peer reviewed proposal basis.

• Synchrotron radiation was originally considered a nuisance to particle physicists because it decreased the particles’ energy. The far-sighted founders of SSRL siphoned off the unwanted radiation, realizing they had the world’s most intense x-ray source, many times more powerful than any conventional x-ray sources could ever produce.

• In 1990, the SPEAR machine was turned over solely to synchrotron radiation research.

• The ring is one-fourth kilometer in circumference and 80 meters in diameter. Its x-ray beams can be used to take images on the sub nanometer scale (one billionth of a meter).

• The synchrotron radiation illuminates everything from radioactive material to the workings of DNA. What researchers see can help them design drugs, gauge the toxicity of environmental pollution and overcome impurities in high-tech materials like silicon chips.

• SSRL expects to operate SPEAR3 24/7, 10 months a year, delivering hard and soft x-rays and ultraviolet light to 32 experimental stations.

• The major milestone of first electrons circulating around SPEAR3 occurred on December 12, 2003.

• Innovations: SSRL has pioneered many new technological and scientific developments in synchrotron research, including permanent magnet wigglers and undulators, synchrotron structural biology (including MAD phasing, XAS, photoemission) and other new techniques for surface and intersurface studies. These advances helped spawn some 50 second- and third-generation synchrotron light sources around the globe.

•Since 1974, SSRL has served over 5,600 unique users (many scientists return for multiple experiments) and users have reported results in more than 6,000 publications.

•Tech notes: The SPEAR3 storage ring will produce beams having one to two orders of magnitude higher brightness and flux density than the old SPEAR2 ring, accommodate many new high performance insertion devices and beam lines, and—with time—become capable of top-off operation by virtue of its improved at-energy injection system. Brightness for new undulators exceeds 1018 at 5 keV.

• Operations and Development: SSRL is supported by the DOE Office of Basic Energy Sciences and the SPEAR3 upgrade jointly funded by DOE-BES and NIH. The SSRL Structural Biology Program is supported by the DOE Office of Biological and Environmental Research and NIH.


The Stanford Linear Accelerator Center is managed by Stanford University for the US Department of Energy

Last update Friday January 30, 2004 by Kathy B