Validating non-linear Compton scattering models through signatures in scattered angular spectra*

Colliding beam experiments, where high intensity laser pulses are collided head-on with energetic electron beams are a promising method for investigating non-linear Compton scattering (NLCS) in the laboratory. Validating the models used for NLCS in theory and simulations is of great importance to extreme astrophysics and future ultra-intense laser-plasma experiments. Experiments have focused on measuring photon spectra and shifts in the electron spectra due to radiation reaction. However, measuring electron and photon spectra with sufficient accuracy to differentiate between models (quantum and classical) has proven to be challenging. We extend the set of signatures that may allow us to differentiate between radiation models and approximations used to simulate NLCS (local constant field and local monochromatic), by looking at the scattered angularly resolved photon spectra. Various simulations are performed in the Monte Carlo code Ptarmigan to pick out signatures from the angular photon spectra and observe how they vary with beam properties. Additionally, detection methods for these signatures are proposed.