Multi-bend Achromat Lattices for Storage Ring Light Sources.

One of the most important factors for synchrotron radiation research is the brilliance, typically defined as photon flux emitted into a unit solid angle from a unit source size within a defined relative bandwidth. The product of rms solid angle and source size yields the beam emittance. To reach high brilliance, both the horizontal and vertical beam emittance must be small and the stored beam current high. Even at zero emittance, radiative diffraction effects produce a finite volume of phase space of the radiation [1], with the effective photon beam emittance given by: where λ is the X-ray-wavelength and Eγis the photon beam energy. In recent years, the user community has become increasingly interested in the transverse coherence properties of the X-ray beam. By using the half-Airy disk criterion [2], the coherent fraction of the emitted coherent light is given in Eq. (2), where εitotis the total emittance, including the contribution of the electron beam and the undulator radiation. [ABSTRACT FROM PUBLISHER]