SCT Experiment

# Accelerator Complex

The SCT factory is a symmetric electron-positron collider consisting of the following installations:

1. Positron injector with cooling storage ring
2. Injector of polarized electrons
3. Linear accelerator producing the beams at the energy of the experiment
4. Double ring collider

## Collider

The collider has the following features:

• high single-bunch luminosity due to the Crab Waist collision scheme with large Piwinski angle and submillimeter vertical beta function at the interaction point;
• multi-bunch regime, which implies the use of the double ring scheme;
• the final focus on the basis of superconducting quadrupole lenses, providing a small beta function;
• small horizontal and vertical beam emittances;
• high intensity of a short bunch (∼10 mm);
• effective control of the damping parameters (emittance, damping time, etc.) to ensure maximum luminosity in the entire energy range;
• high level of longitudinal polarization of the electron beam in the entire energy range.
Parameter 1.5 GeV 2.5 GeV 3.5 GeV
Perimeter, $$\Pi$$ (m) 632.94
Beams crossing angle, $$2\theta$$ (mrad) 60
RF frequency, $$f_0$$ (MHz) 350
Beta function at the interaction point $$\beta_x^*/\beta_y^*$$ (mm) 100/1
Number of bunches 292 328 262
Number of electrons in each bunch ($$10^{10}$$) 9 8 9
Beam current $$I$$ (A) 2
$$\xi_x/\xi_y$$ 0.007/0.15 0.003/0.1 0.004/0.08
Luminosity, $$L$$ ($$10^{35}$$ cm$${}^{-2}$$s$${}^{-1}$$) 0.8 1.0 1.0

## Injector

The SCT injector contains a number of acceleration modules. Each acceleration module consists of klystron, power multiplication system, and two acceleration sections. The injector provides top-up injection electrons and positrons at the experiment energy with frequency of 50 Hz.