SPEAR3 Accelerator


SSRL utilizes x-rays produced by its accelerator, the Stanford Positron Electron Asymmetric Ring (SPEAR3). Based on a 2004 upgrade funded by the Department of Energy and the National Institutes of Health, SPEAR3 is a 3-GeV, high-brightness third generation storage ring operating with high reliability and low emittance. SSRL runs with 500 mA in top-off mode, during which the beam current is kept constant with injection of electrons into the ring every five minutes.

The SSRL storage ring team is in the final stages of installing hardware that will enable reducing the SPEAR3 emittance to 6 nm from its present value of 10 nm.  The last piece is the installation of the thin septum injection magnet that will occur in the summer of 2018.  Work to implement the new lower emittance optics in SPEAR3 operations will proceed after the 2018 summer shutdown.

State-of-the-Art Experimental Facilities

SSRL offers more than 30 experimental stations, supporting a variety of techniques including: macromolecular crystallography, soft and hard x-ray microscopy, microXAS imaging, x-ray scattering and diffraction, photoemission spectroscopy and x-ray absorption and emission spectroscopies.

SPEAR3 Status

SPEAR3: Always Improving

SSRL and SLAC's Accelerator Directorate are continually working to improve SPEAR3 to keep SSRL competitive with synchrotron light sources around the world. The current planned improvements include:

  • Accelerator performance improvements, including improvements in beam quality (brightness, stability and optimization for timing mode experiments) injector enhancements to increase the range of injection options
  • Accelerator reliability improvements along with improvements in spare availability
  • Accelerator research and development that prioritizes future accelerator performance upgrades
  • Next generation synchrotron light source: PEP-X
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