A compact laser-plasma-based scheme for the production of positron beams*

The production of high-quality positron beams is an essential component of a future, plasma-based high-energy electron-positron collider. However, facilities where plasma-based acceleration of positron beams can be experimentally studied are lacking. We present a compact, laser-based scheme for the production of positron beams. Positrons are produced via pair decay of the Bremsstrahlung radiation generated when a multi-GeV, laser-plasma accelerated electron beam interacts with a high-Z solid target. A realistic phase-space distribution for the positrons is obtained by modeling the electron beam interaction with the solid target using the Monte Carlo code Geant4.  The positrons are then injected and accelerated into a second laser-plasma accelerator stage, operating in the linear regime, through a transport line formed by a dipole magnet and an external focusing element.