Electron and Photon spectra in Strong Field QED Scattering Experiments

Scattering electron beam with peta-watt optical lasers is planned for experiments in current and near-future laser facilities. Most analytical models associated with the evolution of the electron distribution function, expected photon emission and pair creation have been developed assuming the laser is a plane wave with a temporal envelope. This approximation is valid for a perfectly synchronized collision (in space and time) where the laser waist is large compared to the electron beam size. In an experiment, not all electrons will interact with the same peak laser field and the laser Poynting instability makes it difficult to ensure the spatial synchronization on all shots. To take this into account, it is possible to estimate the effective laser intensity of interaction for each particle and generalize the scaling laws previously derived to more realistic geometries including 3D effects. Recently, we have shown that the positron yield in focused laser-electron scattering can indeed be estimated using this strategy, where we have derived an analytical description for the effective intensity distribution function [1]. In this work, we developed a semi-analytical model for obtaining the final electron distribution function using both classical and quantum radiation reaction descriptions, and including several non-ideal features such as offset from the laser focus, interaction at an angle (in particular at 90º), non-monoenergetic beams, beam divergence, and tight-focusing. We've compiled these results into a light, parallel, user-friendly open-source toolkit, that can give real-time support for the upcoming laser experiments.