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. Objectives ?Both X25 and X29 are benefitting from improved capability to collect diffraction data routinely from smaller crystals. We have coordinated improvements between the two undulator beamlines to provide the users with a more consistent environment. We are pursuing the development of better ways to find small crystals with both conventional optics and with a grid search using x-rays. We want to implement more diagnostic tools to monitor the stability of the x-ray beam delivered by the NSLS. We are also deploying an automounter at X25 similar to that at X29 Results ? Scanning for Small Crystals: As crystals become smaller, getting the crystal into the beam becomes challenging. Visualizing small crystals with visible light is particularly difficult as the cold stream presents a very different index of refraction for visible light and the cold stream is very dynamic on the scale of 20 microns. The x-ray beams at x25 and x29 can easily be slitted to 20 microns. We then rapidly raster with our versatile crystal positioners and present to the user a 2D map showing where there is diffraction from their crystal. They then click on that map and the crystal is positioned at that location. Repeating this procedure at 90 degrees then centers the crystal to the x-ray beam. This procedure has been enthusiastically embraced by the users that have small crystals, and has greatly sped up the aligning of small crystals. Diagnostic tools ?White beam position monitors: White beam position monitors from synthetic chemical vapor deposition (CVD) diamonds are employed to assess the intensity and stability of the x-ray beam. Employing two of these detectors on beamline X25, we will be able to correlate beam position, and direction, with the x-ray data collections. Furthermore we can troubleshoot positional variations in the x-ray source the better to understand the behavior of the storage ring. Before this work, all beam diagnostics devices on X25 were located downstream from the monochromator and mainly in the experimental hutch. These are convenient to optimize the intensity of the beam for data collection, which consists mainly of optimizing the pitch on the second crystal of the monochromator and recentering the diffractometer in the hutch. A monochromatic beam position monitor (BPM) was installed right after the monochromator a little over a year ago. While useful for monitoring the monochromatic beam intensity and position, it doesn't provide much insight on the position and stability of the white beam. Shortly after the winter 2010 shutdown, we installed a motorized wBPM (white-beam-position monitor) on the first upstream top port of the old mirror tank. This first prototype, described in more details below, served as a proof of concept to test the feasibility and characteristics needed to handle white beam from an undulator source at the NSLS, and is an important stepping stone in developing such a device for upcoming beamlines at NSLS-II. It provides a very useful monitoring of the ring in the X25 vicinity. See the full Research Progress report for a complete description. Plans ?We will install an automounter at X25 in the May maintenance shutdown. We are in the process of installing a second beam position monitor. This work is done in collaboration with the NSLS-II experimental facilities division (J. Kiester), BNL instrumentation group (J. Smedley) and Case Western University (J. Bohon). Thus the pair of beam position monitors allows assessment of the angular trajectory variation of the x-ray beam. Significance ?Being able to monitor the incoming x-rays is crucial for assessing the quality and stability of the beam and fundamental when thinking about mini to micro beams and preparing for new experiments done at NSLS-II. The second device will help monitor the angle of the second beam. This is also valuable to better understand the behavior of the monochromator. The NSLS accelerator groups are also interested to compare their data about the ring position which is harvested with electronic devices (pick up electrode PUE) and compare them with our setup. Studies were done and planned for this summer.
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