Experimental design of radiation reaction by 1 PW laser pulse and linear accelerator electron bunch

Radiation reaction (RR) is the frictional effect of a relativistically energetic and radiating electron. This situation can be created when the energetic electron collides with an ultra-intense laser pulse. We propose a RR experiment by making use of the collision of a 600 MeV electron beam from the linear accelerator and an ultra-intense laser pulse focused to 1022W/cm2 at ELI-NP. Its purpose is to distinguish RR in the quantum-dominant (semi-classical) regime when χ≈0.4 in comparison with the classical RR model, where, χ∝(electronenergy)×laserintensity. The numerical studies demonstrate that scattered electrons with the energy between 80–200 MeV and emitted photons above 300 MeV are needed to clarify the difference between these RR models. The layout of the experiment is proposed to enable the measurements of electron energy spectra and photon polarization by following the numerical results. The parameter N indicating the number of absorbed laser photons by an electron is introduced to express the nonlinearity of RR. The parameter set of (χ,N) resolves the physical regimes of RR and demonstrates a roadmap of the past and future of the RR experiments. The ELI-NP parameter set can provide a plot in the higher-N region as N>5×105 with the almost fixing χ parameter by comparing with the past researches.