Converting conventional electron accelerators to high peak brilliance Compton light sources

Abstract

Several proposals have been put forward for converting electron accelerators to inverse Compton scattering (ICS) gamma sources. Typical approaches suggest combining near-IR solid-state lasers operating continuously at a multimegahertz repetition rate with e-beams when setting their interaction point inside a field-enhancement, Fabry-Perot optical cavity. We introduce here an alternative method of pairing particle accelerator beams with trains of long-wave-infrared, λL≈9-11 μm pulses from a picosecond CO2 laser of a novel architecture operating in a repetitive pulse-burst mode. Because of a considerable increase in the laser energy per pulse, combined with an order-of-magnitude higher number of laser photons per joule of laser energy, our approach allows us to increase the ICS peak flux and brilliance by 4 orders of magnitude compared to previous proposals while maintaining high (1011-1012 ph/s) average flux. This outcome is supported by the examples of the DAφNE and CBETA accelerator facilities, where 1020-1021 ph/(s·mm2·mrad2·0.1%BW) peak brilliances at 50-1000 keV photon energy range can be achieved and is comparable or exceeds the capabilities of contemporary synchrotron light sources at hard x rays. Such high-brightness ICS sources will find applications in pump-probe and other ultrafast studies that require building up meaningful datasets on a single x-ray pulse.