CAREER: Computing Radiation Spectra in Compton Sources with High Precision

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X-rays enable scientists to study the internal structure of materials on all length scales from the macroscopic down to the positions of individual atoms. This capability has had profound impact on science, technology, and on the world economy. The community is in agreement that future advances in many areas of science and technology depend on understanding the structure-function relationships at the nano-scale, where new properties emerge. Controlling the fabrication of complex materials at that scale will allow for novel physical, chemical, and biological functionality. Output flux and brilliance of Compton sources rivals, and by some measures exceeds, modern synchrotron sources, bringing the most advanced scientific and medical X-ray probe into the university, industrial, and medical laboratory. In this context, this project will improve the calculation of radiation spectra in Compton sources. If successful, the new approach is expected to play a pivotal role in ushering a new era in hard X-ray source technology. Combined with powerful optimization tools, this will lead to substantial improvements in performance for all existing and future Compton sources.When a relativistic electron beam interacts with a laser beam, intense and highly collimated electromagnetic radiation is generated through Compton scattering. Increasing the laser intensity changes the longitudinal velocity of the electrons during their collision, which leads to considerable broadening in the scattered radiation spectra. The effects of such ponderomotive broadening are so deleterious that most Compton sources either remain at low laser intensities or pay a steep price to operate at a small fraction of the physically possible peak spectral output. In this project, the PI and his collaborators will build on previous work that showed that the ponderomotive broadening for individual electrons can be eliminated by suitable frequency modulation (chirping) of the incident laser wave. The PI will generalize this chirping prescription to realistic electron beams and laser pulses, in order to quantify its advantages. High-fidelity simulations of Compton sources with chirping are expected to lead to substantial savings in the operational costs of the existing as well as the design and construction cost of new Compton sources.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.