Small-angle X-ray scattering beamline at SPring-8, RIKEN structural beamline 1 (BL45XU)

RIKEN structural biology beamline I (BL45XU) is an undulator beamline with two branches. One is for protein crystallography (PX) and the other is for small-angle x-ray scattering (SAXS). The beam is split into the two branches by diamond monochromator so that PX and SAXS experiments can be done simultaneously [Yamamoto et al. (1995) Rev. Sci. Instrum. 66, 1833-1835]. The SAXS branch was designed for studying the weak interaction of proteins or subunits of fibers or protein solution, especially using hydrostatic pressure. The clean and stable optics were realized by an undulator source with diamond monochromator and a K-B type focusing mirror system. The optics was optimized at the wavelength of 1.0 A, rather than 1.5 A, while the lower limit of recording angle is small (d≅1400 A-1). Collimated beam has a size of 0.6 x 0.3 mm (horizontal x vertical) with a flux of 1 x 1012 photons at 100 mA. In order to cope with high flux of the beam, an X-ray image intensifier with a cooled CCD camera (Hamamatsu Photonics) is used. The use of this detector to solution X-ray scattering has been systematically studied. (author)