State-of-the-Art Experimental Facilities
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. Most recently, the SSRL storage ring team has been working to reduce the SPEAR3 emittance.
SSRL continually works to improve SPEAR3 to remain competitive with synchrotron light sources around the world, including:
- Accelerator performance 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
3 GeV
Electron storage ring
7 nmrad
Emittance and top-off injection
Current
97%+
Reliability
| Beam Line | Status | Steering | Periods | Gap (mm) | Field(T) | K | Power (W) | Yield (Ah) |
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| 17 |
Top-Off Mode:
Total Run Electron Beam Current Integral:
Photon Source Parameters
| Parameter | Value |
|---|---|
| Beam Energy | 3 GeV |
| Injection Energy | 3 GeV |
| Current | 500 mA |
| Fill Pattern | 276 bunches distributed in 4 groups of 69 bunches each, plus 1 "camshaft" bunch |
| Circumference | 234.137 |
| Radio Frequency | 476.315 MHz |
| Bunch Spacing | 2.1 ns |
| Horizontal Emittance | 7 nm*rad |
| Vertical Emittance | 30 pm*rad |
| Critical Energy | 7.6 keV |
| Energy Spread | 0.10 |
| Lifetime | 6 hours |
| e- size (x,y) | Dipole: 123, 11 µm rms Standard ID: 270, 6.6µm rms Chicane ID: 296, 3.6 µm rms Matching ID: 249, 4.5 µm rms |
| e- divergence (x,y) | Dipole: 165, 2.3 µrad rms Standard ID: 28, 1.25 µrad rms Chicane ID: 27, 2.3 µrad rms Matching ID: 27, 1.8 µrad rms |
| Bunch Length | 20 psec rms (6.1 mm rms) |
| Straight sections for IDs (available ID length) |
9 x 2.3 m 4 x 3.7 m 2 x 1.5 m (Chicane) |