Gamma-induced positron beam generation at SLEGS

Energy-variable gamma-rays are produced in laser Compton slant-scattering (LCSS) mode at the ShanghaiLaser Electron Gamma Source (SLEGS), a beamline of the Shanghai Synchrotron Radiation Facility (SSRF, alsocalled Shanghai Light Source). Based on the SLEGS energy-variable gamma-ray beam, a positron-generationsystem composed of a gamma-ray-driven section, positron-generated target, magnet separation section, andpositron experimental section was designed for SLEGS. Geant4 simulation results show that the energy tunablepositron beam in the energy range of?1 to?12.9 MeV?with a flux of?3.7×104?to?6.9×105?e?+/s?can be produced inthis positron-generation system. The positron beam generation and separation provide favorable experimentalconditions for conducting non-destructive positron testing on SLEGS in the future. The positron-generationsystem is currently under construction and will be completed in 2025.