title: 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 x 10(11) photons s(-1) at 1 A wavelength, at a beamline aperture of 1.5 mrad (horizontal) x 86 microrad (vertical), with energy resolution (limited mostly by the intrinsic resolution of the monochromator optics) deltaE/E = 1.5 x 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 microm (horizontally) x 160 microm (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.
authors.affiliation: IMCA-CAT, The Center for Advanced Radiation Sources, University of Chicago, IL 60637, USA. ikoshelev@anl.gov
authors.forename: Irina
authors.initials: I
authors.lastname: Koshelev
authors.forename: Rong
authors.initials: R
authors.lastname: Huang
authors.forename: Timothy
authors.initials: T
authors.lastname: Graber
authors.forename: Mati
authors.initials: M
authors.lastname: Meron
authors.forename: J Lewis
authors.initials: JL
authors.lastname: Muir
authors.forename: William
authors.initials: W
authors.lastname: Lavender
authors.forename: Kevin
authors.initials: K
authors.lastname: Battaile
authors.forename: Anne M
authors.initials: AM
authors.lastname: Mulichak
authors.forename: Lisa J
authors.initials: LJ
authors.lastname: Keefe