Spin and Polarization in High-Intensity Laser-Plasma Interactions

With the ongoing progress of high-power laser developement, high-intensity QED effects are playing an increasingly important role in high-intensity laser plasma interactions. In this talk I will elaborate why electron-spin and photon-polarization will be a relevant subject in high-intensity laser-plasma and laser-beam interactions in the near future due to the fundamental QED processes in strong fields being sensitive to the particle polarization.

    

Some of the predicted effects on particle polarization share similarities with the Sokolov-Ternov effect---the radiative polarization of electrons in storage rings---but they occur on much faster femtosecond time-scales due to the large quantum efficiency parameter. I will discuss how those effects might be capitalized for generating spin-polarized beams for future plasma-based high-energy-physics colliders, which crucially depend on having spin-polarized beams available.

    

Moreover, we have studied the relevance of spin and polarization for the formation of a avalanche-like QED cascade where copious amounts of spin-polarized matter and polarized photons can be produced. We found that the particle polarization affects the cascade growth rate. Moreover, the highest energy particles are polarized opposite the expectation from Sokolov-Ternov theory, which cannot be explained by just taking into account spin-asymmetries in the pair production rates, but results significantly from the phenomenon of ``spin-straggling''.