MICRODIFFRACTION DEVELOPMENT

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。 在此周期中，我们进行了以下与BioCAT微衍射程序相关的开发。 我们做了一个新版本的样品校准系统。用较小的棱镜替换棱镜，并将组件移动到靠近孔侧的样品位置上游。这允许将样品保持器移动到He室的前窗附近，从而减小样品和室之间的气隙。我们观察到这种新的安排，空气散射显着减少。我们还加入了一组狭缝和一个可以疏散的长鼻子。该装置直接位于KB镜的下游，以提供具有非常低的寄生散射的干净且轮廓分明的光束。这种狭缝和孔径的组合产生了非常干净的背景，这在处理微弱和漫散射/衍射信号时是必不可少的。CCD检测器支架也经过了修改，加入了允许沿光束方向沿着移动的导轨。这些导轨有助于减少在更改相机长度时重新定位探测器所需的时间。 新的飞行管也被纳入该系统。这些都是标准的不锈钢管，允许选择腔室距离从100毫米到300毫米非常容易。 将样品保持在仪器低温下的能力也得到了改进。

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. During this cycle we have performed the following developments related to the BioCAT micro diffraction program. We made a new version of the sample alignment system. The prism was replaced by a smaller one and the assembly was moved upstream the sample position next to the aperture side. This allows moving the sample holder near the front window of the He chamber and therefore reduces the air gap between sample and chamber. We observed a significant reduction of air scattering with this new arrangement. We also incorporated a set of slits and a long snout that can be evacuated. The arrangement is located immediately downstream the KB mirrors to provide a clean and well-defined beam with very low parasitic scattering. This combination of slits and aperture yielded very clean backgrounds, which is essential when dealing with weak and diffuse scattering/diffraction signals.The CCD detector mount was also modified by incorporating rails that allows moving it along the beam direction. These rails help reduce the time needed to relocate the detector when changing the camera length. New flight tubes were also incorporated to the system. These are standard stainless steel tubes that allow selecting chamber distances from 100 mm to 300 mm very easily. The ability to maintain samples at cryogenic temperature in the instrument have been also improved.