Observation of polarized positrons from an undulator-based source

Area of Science:

• Particle Physics
• Accelerator Physics
• Photon Science

Background:

• Producing polarized positrons is crucial for fundamental physics research and applications.
• Previous methods for generating polarized positrons were limited in efficiency and polarization degree.

Purpose of the Study:

• To demonstrate a novel scheme for generating high-energy, longitudinally polarized positrons.
• To validate the experimental results with advanced simulation tools.

Main Methods:

• An experiment (E166) at the Stanford Linear Accelerator Center utilized a multi-GeV electron beam.
• The electron beam traversed a helical undulator to produce circularly polarized photons.
• Photons converted into positrons and electrons in a thin target, yielding longitudinally polarized positrons.

Main Results:

• Achieved longitudinal polarization of positrons above 80% at 6 MeV.
• Demonstrated successful generation of multi-MeV, circularly polarized photons.
• Experimental data aligned with GEANT4 simulations, including polarization-dependent interactions.

Conclusions:

• The demonstrated scheme is effective for producing high-quality polarized positrons.
• GEANT4 simulations accurately model the complex polarization-dependent interactions involved.
• This technique offers a promising pathway for future high-energy physics experiments requiring polarized positrons.