Accelerator Seminar: Geoffrey Krafft

Speaker: Geoffrey Krafft

Subject: Scattered Spectra from Non-linear Compton Effect

Abstract: Compton famously studied frequency shifts in the scattering of electromagnetic radiation in his Noble-prizewinning work. The so-called Compton effect provided one of the earliest experimental verifications of the existence of separate, individual photons in beams of electromagnetic radiation. Recently, prodded by the desire to construct intense narrowband sources of x-rays or gamma rays, photon sources based on the scattering of laser radiation from relativistic electron beams have been built and operated. Most present devices operate in regimes where linear (first order QED) calculations of the spectrum of the scattered radiation apply. In the future, however, when more intense lasers are available, non-linear Compton scattering obtains. A group at Old Dominion University has developed new methods allowing this more general case to be calculated precisely. After reviewing spectrum calculations in the context of some existing and contemplated Compton Sources, several new predictions involving non-linear Compton scattering will be presented. In particular, we have demonstrated through calculation that proposed performance enhancements in Compton sources by frequency chirping extend to the highest harmonics emitted from the source and are remarkably insensitive to being degraded by electron beam thermal effects.

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