Focusing, collimation and flux throughput at the IMCA-CAT bending-magnet beamline at the Advanced Photon Source

Abstract

The IMCA‐CAT bending‐magnet beamline was upgraded with a collimating mirror in order to achieve the energy resolution required to conduct high‐quality multi‐ and single‐wavelength anomalous diffraction (MAD/SAD) experiments without sacrificing beamline flux throughput. Following the upgrade, the bending‐magnet beamline achieves a flux of 8 × 1011 photons s−1 at 1 Å wavelength, at a beamline aperture of 1.5 mrad (horizontal) × 86 µrad (vertical), with energy resolution (limited mostly by the intrinsic resolution of the monochromator optics) δE/E = 1.5 × 10−4 (at 10 kV). The beamline operates in a dynamic range of 7.5–17.5 keV and delivers to the sample focused beam of size (FWHM) 240 µm (horizontally) × 160 µm (vertically). The performance of the 17‐BM beamline optics and its deviation from ideally shaped optics is evaluated in the context of the requirements imposed by the needs of protein crystallography experiments. An assessment of flux losses is given in relation to the (geometric) properties of major beamline components.

Size-changeable x-ray beam collimation using an adaptive x-ray optical system based on four deformable mirrors

“…Users often utilize collimated beams as well as focusing and divergent beams. Although they are usually formed with crystal collimators 8 , refractive lenses 9 and total-reflection mirror 10,11 systems, they cannot produce adaptive collimations that can change the beam size. Furthermore, it is impossible to realize seamless switching between focused and collimated beams.…”

Sagittal focusing of synchrotron radiation X-rays using a winged crystal

“…Two-dimensional focusing by combining a bent second crystal in a double-crystal monochromator (Sparks et al, 1980(Sparks et al, , 1982 and a tangential-focusing mirror is an efficient method of increasing the flux density at bending-magnet and wiggler beamlines (e.g. Borsboom et al, 1998;Bilsborrow et al, 2006;Koshelev et al, 2009;Nomura & Koyama, 1999;Yoneda et al, 2005). Another efficient method is the combination of a double-crystal monochromator with plane-plane crystals and a two-dimensional focusing mirror (Kirkpatrick-Baez mirror, toroidal mirror or tangentially bent cylindrical mirror).…”

“…Various solutions have been proposed to minimize anticlastic bending, such as by using a ribbed (Borsboom et al, 1998;Bilsborrow et al, 2006), hinged or slotted crystal (e.g. Sparks et al, 1982;Kushnir et al, 1993;Schulze et al, 1998;Yoneda et al, 2001;Feng et al, 2008;Koshelev et al, 2009) with various types of bend mechanism for bending-magnet, wiggler and undulator beamlines. Since a slotted crystal has a smoother reflective surface than both ribbed and hinged crystals, it is suitable for fine focusing.…”