Production of highly-polarized positrons using polarized electrons at MeV energies

TL;DR

This study demonstrates a novel method for producing highly polarized positrons at MeV energies by transferring polarization from polarized electrons, significantly expanding polarized positron applications to lower energy regimes.

Contribution

It introduces an efficient polarization transfer technique from polarized electrons to positrons at MeV energies, previously limited to GeV energies.

Findings

Positron polarization up to 82% achieved

Effective polarization transfer demonstrated at 8.19 MeV/c

Technique enables access to polarized positron physics at MeV energies

Abstract

The Polarized Electrons for Polarized Positrons experiment at the injector of the Continuous Electron Beam Accelerator Facility has demonstrated for the first time the efficient transfer of polarization from electrons to positrons produced by the polarized bremsstrahlung radiation induced by a polarized electron beam in a high-$Z$ target. Positron polarization up to 82\% have been measured for an initial electron beam momentum of 8.19~MeV/$c$, limited only by the electron beam polarization. This technique extends polarized positron capabilities from GeV to MeV electron beams, and opens access to polarized positron beam physics to a wide community.