Shallow-angle inverse Compton scattering: Experimental demonstration and future applications

Inverse Compton scattering (ICS) at shallow angles can be used to tune the spectrum and increase the brightness of the emitted radiation. Here, we investigate the geometric scaling laws governing this interaction and experimentally validate them by demonstrating shallow-angle ICS of a 780 nm laser crossing a 4.7 MeV electron beam at 5.8°. Angular and spectral measurements of the emitted radiation show excellent agreement with analytical and numerical predictions. To further optimize this interaction, we consider the use of velocity-matched pulse-front tilt to decouple the total yield from the interaction bandwidth. The resulting framework is used to evaluate the performance scaling of three distinct driving accelerator architectures: a radio-frequency linac, a laser wakefield accelerator, and a storage ring synchrotron. These results establish a scalable, practical pathway for deploying next-generation, high-brightness compact light sources across diverse accelerator platforms.