New diffractometer for high-energy synchrotron radiation at the elliptical multipole wiggler at the APS

The use of high energy synchrotron radiation (above 80 keV) for diffraction experiments offers many advantages resulting from the high penetration depth of the high energy photons and the small Bragg angles. The main features are: the possibility for the study of large sample crystals in transmission geometry, simple sample environments, high instrumental resolution in reciprocal space, the ability to utilize high momentum transfers and small correction factors for scattered intensities. The experiments performed at this kind of diffractometer are driven by the photon flux, in which the only requirement is a relatively small angular divergence for the incident beam in the scattering plane. The new triple crystal diffractometer introduced here will be installed at the elliptical multipole wiggler beamline at the Advanced Photon Source (APS). Because of the high critical energy of this device, 32 keV, the wiggler will produce high intensities at very high photon energies. To collect up to 1 mrad of the horizontal divergence of the beam, a bent annealed silicon monochromator will scatter and focus in the horizontal scattering plane. The diffractometer will be operated in the vertical scattering plane taking advantage of the small vertical beam divergence.