Abstract
We report and discuss high-flux generation of circularly polarized γ-rays by means of Compton scattering. The γ-ray beam results from the collision of an external-cavity-enhanced infrared laser beam and a low emittance relativistic electron beam. By operating a non-planar bow-tie high-finesse optical Fabry-Perot cavity coupled to a storage ring, we have recorded a flux of up to (3.5 ± 0.3) × 108 photons per second with a mean measured energy of 24 MeV. The γ-ray flux has been sustained for several hours. In particular, we were able to measure a record value of up to 400 γ-rays per collision in a full bandwidth. Moreover, the impact of Compton scattering on the electron beam dynamics could be observed resulting in a reduction of the electron beam lifetime correlated to the laser power stored in the Fabry-Perot cavity. We demonstrate that the electron beam lifetime provides an independent and consistent determination of the γ-ray flux. Furthermore, a reduction of the γ-ray flux due to intrabeam scattering has clearly been identified. These results, obtained on an accelerator test facility, warrant potential scaling and revealed both expected and yet unobserved effects. They set the baseline for further scaling of the future Compton sources under development around the world.
Highlights
High-intensity X- and γ-ray beams are extremely useful in fundamental and applied physics as well as in the fields of medicine, material studies, cultural heritage preservation, etc.[1,2,3,4,5]
It should be pointed out that due to the accelerator operation constraints and given the location of the Fabry-Perot Cavity (FPC) installation in the Damping Ring (DR), the parameters of the electron beam in the interaction point have not been optimized during the Compton scattering experimental campaign
The rate is predominantly influenced by the laser power in the FPC or more precisely the circulating pulse energy EL and the charge Qe of the electron beam that is measured with a DC current transformer (DCCT)
Summary
High-intensity X- and γ-ray beams are extremely useful in fundamental and applied physics as well as in the fields of medicine, material studies, cultural heritage preservation, etc.[1,2,3,4,5]. Based on our previous experience[17] we have built a non-planar bow-tie Fabry-Perot Cavity (FPC)[18] to store an infrared laser beam with up to 50 kW of average power consisting of picosecond pulses circulating at a repetition rate of 178.5 MHz making its design and properties different from that of higher frequencies and higher finesse cavities[19] Such design of the FPC has the advantage of being more stable when providing a small beam waist ensuring circularly polarized fundamental eigenmodes and has been adopted given the mechanical constraints of the installation at the accelerator facility. It is the purpose of the ongoing research topic of high finesse passive cavity damping, where the advances presented will certainly benefit[23]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
