High-Energy Bragg and Laue Monochromators for an APS Wiggler Beamline

The elliptical multipole wiggler located at Sector 11 of the Advanced Photon Source has a maximum critical energy of 32 keV and a total power output of ~ 8 kW. The device produces circularly polarized X-rays on-axis and linearly polarized X-rays above and below the ring plane. A double crystal monochromator intercepts the lower linearly polarized radiation to be used in the 11ID-D experimental station for scattering and spectroscopy experiments in the 5 to 40 keV energy range. The on-axis circularly polarized photons and upper linearly polarized photons are monochromatized by one crystal horizontally deflecting monochromators at fixed Bragg angles of = 3.8 deg and = 1.9 deg respectively. We will present here the designs and detail the performance of Laue and Bragg monochromator designs for these two beamlines which operate at fixed energies from ~60 keV to 125 keV. For the high-energy diffraction station, 11ID-C, which utilizes the upper linearly polarized radiation, the Laue monochromator design allows rapid interchange of crystals and provides a photon flux of 2 X 1012 photons/sec in a 2.5 X 3.5 mm spot at 98 keV using annealed Silicon crystals (Si(220)). The Bragg monochromator design provides focusing and a smaller bandwidth while retaining a high photon flux. The high heatloads generated by the EMPW present design challenges for both monochromator designs.