Extremely low vertical-emittance beam in the accelerator test facility at KEK

Area of Science:

• Particle accelerators
• Beam physics
• High-energy physics

Background:

• Achieving low emittance is crucial for advanced accelerator applications.
• Previous methods struggled to minimize vertical emittance effectively.

Purpose of the Study:

• To produce and confirm electron beams with record-low normalized transverse emittance.
• To develop a tuning method for damping rings to reduce vertical dispersion and orbit coupling.

Main Methods:

• Single-bunch-mode operation at the KEK Accelerator Test Facility.
• Implementing a novel tuning method for the damping ring.
• Measuring beam emittance at various intensities and energies (1.3 GeV).

Main Results:

• Record-low normalized transverse emittance achieved for electron beams.
• Vertical emittance was reduced to less than 1% of horizontal emittance.
• Vertical normalized emittance below 2.8 x 10(-8) rad m at 1.3 GeV.
• Observed strong intrabeam scattering effects at high intensity due to high particle density.

Conclusions:

• The developed tuning method successfully minimized vertical emittance.
• The results pave the way for high-brightness electron beams.
• Intrabeam scattering effects must be considered for future high-intensity, low-emittance beams.