Angular spectrum characteristics of relativistic inverse compton harmonic X-rays

The X-ray spectrum emitted during relativistic non-linear inverse Compton scattering is angularly resolved, and energy analyzed through the use of K-edge and attenuation filters. A 0.5 nC electron beam of 65 MeV energy was employed, colliding with a highly intense CO2 laser of normalized vector potential aL∼0.5. In this experiment, 2nd harmonic radiation was clearly observed. In addition, evidence for the 3rd harmonic component of the radiation, having radiation angle of < 1/γ has been found. This measurement represents a significant step forward in experimental understanding the electrodynamics of ICS in the nonlinear regime.