Trapping and acceleration of spin-polarized positrons from γ photon splitting in wakefields

Energetic spin-polarized positrons are very useful for forefront research such as e(-) e(+) collider physics, but it is still quite challenging to generate such sources. Here, we propose an efficient scheme of trapping and accelerating polarized positrons in plasma wakefields. By developing a fully spin-resolved Monte Carlo method, we find that in the nonlinear Breit-Wheeler pair production the polarization of intermediate gamma photons significantly affects the pair spin polarization, and ignoring this effect would result in an overestimation of the pair yield and polarization degree. In particular, seed electrons colliding with a bichromatic laser create polarized gamma photons which split into e(-) e(+) pairs via the nonlinear Breit-Wheeler process with an average (partial) positron polarization above 30% (70%). Over 70% of positrons are then trapped and accelerated in the recovered wakefields driven by a hollow electron beam, obtaining an energy gain of 3.5 GeV/cm with slight depolarization. Our method provides the potential for constructing compact polarized positron sources for future applications and may also attract broad interest in strong-field physics, high-energy physics, and particle physics.

Automated summary

In this paper, an efficient scheme of trapping and accelerating polarized positrons in plasma wakefields is proposed. The results show that polarized positron sources with high spin polarization can be generated, which provides potential for future applications and may attract broad interest in other physics fields.