DEVELOPMENT OF A 2-DIMENSIONALLY TUNABLE FOCUSING MONOCHROMATOR FOR PROTEIN CRYSTALLOGRAPHY AT HIGH-ENERGY UNDULATOR BEAMLINES

A two-dimensionally tunable focusing monochromator has been developed for protein crystallography at high-energy undulator beamlines of thir d-generation synchrotron radiation facilities. This monochromator cons ists of a silicon wafer fabricated with an oblique-cut angle between t he Bragg net plane and the crystal surface, and adhered onto a table-l ike copper block. The radii of curvatures are altered independently in two directions by expanding the spaces between the table legs. The ve rsatilities of the meridional and sagittal curvatures were confirmed b y X-ray experiments and three-dimensional shape measurements, respecti vely. The two-dimensional focusing ability was demonstrated using high -energy X-rays of 37.7 keV emitted from a bending-magnet source at the Photon Factory. A quasi-isotropic profile of converged X-rays was ach ieved near the focal position. The apparent gain of photon flux was 21 . As a result of these excellent monochromator characteristics, a diff raction pattern of a hen egg-white lysozyme crystal was successfully o btained using high-energy X-rays.