MICRODIFFRACTION AT BEAMLINES X25 AND X29

这个子项目是许多利用资源的研究子项目之一 由NIH/NCRR资助的中心拨款提供。子项目的主要支持 而子项目的主要调查员可能是由其他来源提供的， 包括其它NIH来源。 列出的子项目总成本可能 代表子项目使用的中心基础设施的估计数量， 而不是由NCRR赠款提供给子项目或子项目工作人员的直接资金。 目标  X25和X29都受益于从较小晶体常规收集衍射数据的改进能力。我们已经协调了两个波荡器光束线之间的改进，为用户提供更一致的环境。我们正在寻求更好的方法来找到小晶体，既有传统的光学，也有使用X射线的网格搜索。我们希望使用更多的诊断工具来监测NSLS提供的X射线束的稳定性。我们还在X25部署了一个与X29类似的自动装载机 结果  扫描小晶体：随着晶体变得越来越小，将晶体放入光束变得越来越具有挑战性。用可见光观察小晶体是特别困难的，因为冷流对可见光呈现出非常不同的折射率，并且冷流在20微米的尺度上是非常动态的。在x25和x29处的X射线束可以容易地被切割到20微米。然后，我们用我们的多功能晶体定位仪快速光栅扫描，并向用户展示一个2D地图，显示晶体衍射的位置。然后他们点击地图，水晶就被定位在那个位置。以90度重复此过程，然后将晶体置于X射线束的中心。这个过程已经被具有小晶体的用户热情地接受，并且极大地加速了小晶体的对准。 诊断工具  白色光束位置监视器：来自合成化学气相沉积（CVD）金刚石的白色射束位置监测器用于评估X射线射束的强度和稳定性。在光束线X25上使用两个这样的探测器，我们将能够将光束位置和方向与X射线数据收集相关联。此外，我们可以排除X射线源中的位置变化，以更好地理解存储环的行为。 在这项工作之前，X25上的所有光束诊断设备都位于单色器的下游，主要位于实验室中。这些都是方便的优化数据收集的光束强度，主要包括优化第二个晶体的单色器和重新中心的衍射仪在橱柜中的间距。一年多前，在单色仪之后安装了单色光束位置监测器（BPM）。虽然对于监测单色光束强度和位置很有用，但它不能提供关于白色光束的位置和稳定性的更多见解。 在2010年冬季关闭后不久，我们在旧镜箱的第一个上游顶部端口安装了一个电动wBPM（白光位置监视器）。第一个原型，在下面更详细地描述，作为一个概念的证明，以测试的可行性和特性需要处理白色光束从波荡器源在NSLS，是一个重要的垫脚石，在开发这样的设备，即将在NSLS-II的光束线。它提供了一个非常有用的监测环在X25附近。 请参阅完整的研究进展报告以获得完整的描述。 计划  我们将在五月的维修停工中在X25安装一个自动装卸机。我们正在安装第二个光束位置监测器。这项工作是与NSLS-II实验设施部门（J. Kiester），BNL仪器组（J. Smedley）和Case Western大学（J. Bohon）合作完成的。因此，该对射束位置监测器允许评估X射线射束的角轨迹变化。 意义  能够监测入射的X射线对于评估光束的质量和稳定性至关重要，并且在考虑小型到微型光束并为在NSLS-II进行的新实验做准备时至关重要。第二个装置将帮助监测第二束的角度。这对于更好地理解单色器的行为也是有价值的。NSLS加速器小组也有兴趣比较他们的数据，这些数据是用电子设备（拾取电极PUE）收集的，并将它们与我们的设置进行比较。研究已经完成，并计划在今年夏天进行。

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.