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

• Published in: Journal of synchrotron radiation Vol. 16; no. 5; pp. 647 - 657
• Main Authors: Koshelev, Irina, Huang, Rong, Graber, Timothy, Meron, Mati, Muir, J. Lewis, Lavender, William, Battaile, Kevin, Mulichak, Anne M., Keefe, Lisa J.
• Format: Journal Article
• Language: English
• Published: 5 Abbey Square, Chester, Cheshire CH1 2HU, England International Union of Crystallography 01.09.2009
• Subjects: ACCELERATOR FACILITIES; ADVANCED PHOTON SOURCE; bending magnet; collimation; CRYSTALLOGRAPHY; DIFFRACTION; ENERGY RESOLUTION; flux throughput; FOCUSING; macromolecular crystallography; MIRRORS; MONOCHROMATORS; PARTICLE ACCELERATORS; PROTEINS; sagittal focusing; X-rays
• DOI: 10.1107/S0909049509022353
• ISSN: 1600-5775; 0909-0495

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.