Small-angle X-ray scattering (SAXS) measurements of proteins in solution are becoming increasingly popular with biochemists and structural biologists owing to the presence of dedicated high-throughput beamlines at synchrotron sources. As part of the ESRF Upgrade program a dedicated instrument for performing SAXS from biological macromolecules in solution (BioSAXS) has been installed at the renovated BM29 location. The optics hutch has been equipped with new optical components of which the two principal elements are a fixed-exit double multilayer monochromator and a 1.1 m-long toroidal mirror. These new dedicated optics give improved beam characteristics (compared with the previous set-up on ID14-3) regarding the energy tunability, flux and focusing at the detector plane leading to reduced parasitic scattering and an extended s-range. User experiments on the beamline have been successfully carried out since June 2012. A description of the new BioSAXS beamline and the set-up characteristics are presented together with examples of obtained data.
A ®xed-exit monochromator has been constructed for computed tomography (CT) studies at the Medical Beamline of the European Synchrotron Radiation Facility. A non-dispersive pair of bent Laue-type crystals is used, and the ®rst crystal is water-cooled. The monochromator operates at energies from 18 to 90 keV, and the maximum width of the beam is 150 mm. The performance of the monochromator is studied with respect to the beam intensity and energy distributions, and a close agreement is found between the calculated and experimental results. The intensity is between 10 9 and 10 10 photons s À1 mm À2 under typical operating conditions. The harmonic content of a 25 keV beam is about 30% at the minimum wiggler gap of 25 mm (®eld 1.57 T) and decreases by an order of magnitude when the gap is increased to 60 mm (®eld 0.62 T). The experimental set-up for CT studies includes dose monitors, goniometers and translation stages for positioning and scanning the object, and a 432-element linear-array Ge detector. Examples from phantom studies and in vivo animal experiments are shown to illustrate the spatial resolution and contrast of the reconstructed images.
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A multicrystal UHV monochromator equipped with up to four different monochromator crystals, which can be exchanged in situ, is described. The monochromator is designed as a transmission monochromator in horizontal scattering geometry allowing the`quasi-white' beam, after transmission through X-ray-transparent diamond or beryllium monochromator crystals, to be utilized in independent downstream stations.
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