Three-dimensional theory of emittance in Compton scattering and x-ray protein crystallography - art. no. 016501

A complete, three-dimensional theory of Compton scattering is described, wh ich fully takes into account the effects of the electron beam emittance and energy spread upon the scattered x-ray spectral brightness. The radiation scattered by an electron subjected to an arbitrary electromagnetic field di stribution in vacuum is first derived in the linear regime, and in the abse nce of radiative corrections; it is found that each vacuum eigenmode gives rise to a single Doppler-shifted classical dipole excitation. This formalis m is then applied to Compton scattering in a three-dimensional laser focus, and yields a complete description of the influence of the electron beam ph ase-space topology on the x-ray spectral brightness; analytical expressions including the effects of emittance and energy spread are also obtained in the one-dimensional Limit. Within this framework, the x-ray brightness gene rated by a 25 MeV electron beam is modeled, fully taking into account the b eam emittance and energy spread, as well as the three-dimensional nature of the laser focus; its application to x-ray protein crystallography is outli ned. Finally, coherence, harmonics, and radiative corrections are also brie fly discussed.