SPEAR3 Accelerator

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
 
SPEAR3 History Plot
SPEAR3 History Plot
SPEAR3 History Plot
SPEAR3 History Plot
 
Updated:
Beam Line Status Steering Periods Gap (mm) Field(T) K Power (W) Yield (Ah)
1
2
4
5
6
7
8
9
10
11
12-1
12-2
13
14
15
16
17
Top-Off Mode:
Total Run Electron Beam Current Integral: Ah

 

SPEAR3 History Plot

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)