CONSTRUCTION OF THE BIO-CRYSTALLOGRAPHY (MIR-OAS) BEAMLINE AT THE SPRING-8. N. Kamiya, Y. Kawano, T. Uruga, H. Kimura, T. Ishikawa, and H. I Kitamura, Jaeri-Riken SPring-8 Project Team, The Institute of Physical and Chemical Research (Riken), Hirosawa 2-1, Wako 35101, Japan

The Bio-Crystallography beamline¹ under construction at the SPring-8 is aimed at routine analyses in macromolecular crystallography by the multiple isomorphous replacement (MIR) technique with optimized anomalous scattering (OAS). The beamline also focuses on data collections for very large macromolecules such as ribosomal particles and viruses and for small crystals less than 100 um. The light source is an invacuum undulator of 3.2 cm magnetic periodicity, which emits highly brilliant X-rays in an energy range of 9 - 38 keV. The highest power and power density of the undulator are 5 kW and 300 kW/mrad², respectively. To handle the tremendous power density a rotated-inclined double-crystal monochromator will be used. The first crystal will be chilled by a pin-post water cooling technique. To focus the high-energy X-rays up to 38 keV, two super mirrors (OSMIC) will be installed to get quasi-isotropic and small beam profile of about 100 um at focal position. This beamline will be characterized by uses of high-energy X-rays up to 38 keV and X-rays (9 - 18 keV) with excellect energy resolution (2 x 104) at one beamline. The former is useful for ideal data collections at high resolution without absorption effects, and the latter is preferred for the OAS data collections of the heavy atom derivatives utilized in the MIR technique. For recording the diffraction patterns, imaging plates (IPs, Fuji Film) of large active area (400 x 500 mm²) will be used as the X-ray detector in the experimental station. To read out the IPs within one minute, a new readout mechanism is under development by using a lineshaped laser beam and a charge-coupled device.

1) N. Kamiya et al., Rev. Sci. Instrum. 66, 1703 (1995).