Macromolecular crystallography station BL-18B at the Photon Factory

Abstract

A new experimental station, BL‐18B, has been constructed on a bending‐magnet beamline at the Photon Factory. The branch beamline is equipped with a Pt‐coated fused quartz bend cylindrical mirror of 1:1 focusing and a fixed‐exit double‐crystal monochromator. The mirror can focus an x‐ray beam to about 0.4 mm (vertical) ×1.2 mm (horizontal). The monochromator consists of two kinds of flat crystals, usually Si(111) and Ge(220), mounted side by side on the goniometer, and those two crystals can be interchanged without opening the vacuum chamber. In addition to increasing the experimental time available to users of the Weissenberg camera, BL‐18B provides a point focused white beam for the time‐resolved Laue method. In order to allow more effective exposures using Weissenberg and Laue methods, a new multipurpose camera using large imaging plates, 400 mm×400 mm and 400 mm×800 mm, is being developed. A special scanner for the large imaging plate has also been developed. Response of the scanner was tested and the linearity between the incident x‐ray photons and the measured intensity is confirmed from 1 to 1×105photons per pixel.