DEVELOPMENT AND COMMISSIONING OF MICROBEAM CAPABILITIES ON BL12-2

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Microbeam mode for studying microcrystals is being developed and implemented for BL12-2. A precision microdiffractometer, developed in-house, is used as the base instrument. An in-line camera is incorporated into the beam line for viewing microcrystals along the beam axis, which reduces misalignments due to parallax. The beam line setup also includes an automated collimation system. Software tools were developed for the microbeam collimation system and the in-line camera. An automated alignment procedure of the microbeam (15 um x 5 um) to the phi axis was implemented. Controls for selecting the microbeam mode and viewing and centering samples with the in-line video camera were implemented in Blu-Ice. The diffraction based crystal centering routine was modified for centering microcrystals. An algorithm to accurately distinguish between diffraction and noise is currently being tested. A significant effort continues to be aimed at addressing beam stability challenges, such as refinement of a helium path system, temperature control system, x-ray beam attenuator and mirror pitch feedback system.