MICRODIFFRACTION AT THE NE-CAT BEAMLINES

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。对用于进行小于20-30微米晶体衍射实验的同步加速器束流线的需求越来越大。NE-CAT¿s相I束流线已经证明了束流线组件的稳定性，可以为常规尺寸晶体的晶体学实验提供稳定、聚焦的x射线束。相位I光束线不是为微衍射定制的。然而，通常NE-CAT用户带来的小晶体，最大尺寸小于30微米。这些晶体中有些会产生衍射数据/结构，有些则不会。我们预计，不久将有越来越多的用户将常规地将这种较小的晶体带到NE-CAT光束线。通过优化束流线成分，可以大大提高小晶体实验的成功率，这样，a)更小的样品可以很容易地可视化，b)可以制作出与样品尺寸匹配的小光束，c)可以减少背景散射。考虑到这些事实，我们已经评估了内部微衍射能力的发展，使用APS设计的角计，其不确定度球体小于2微米，开发高倍率同轴样品成像仪，并升级光束光学以提供干净的微聚焦。虽然这是可行的，但由于我们的技术人员正专注于二期梁线的建设，这可能是一项耗时的工作。因此，为了在尽可能早的时间尺度上为NE-CAT用户提供微衍射能力，我们决定商业购买一台。我们已经向ACCEL授予了Maatel生产的MD2微衍射仪。这种微衍射仪的设计源于欧洲分子生物学实验室（EMBL），该实验室的设备已成功用于ESRF和SLS。有了这个微绕射仪，我们期望能够常规地研究尺寸为几微米的晶体，使用定制为类似尺寸的光束，以减少散射污染和背景。我们的工厂将是美国第一家这样的工厂。预计将于2006年9月交付，也就是预定的APS维修关闭期。MD2将首先安装在第二期波束线上，这样波束线和MD2可以同时投入使用，而不会影响第一期用户计划。我们希望在2006年底提供MD2的早期用户时间。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. There is increasing demand for synchrotron beam lines equipped for carrying out diffraction experiments with crystals smaller than 20-30 microns. NE-CAT¿s phase I beam line has demonstrated the stability of the beam line components to provide stable, focused X-ray beam for crystallographic experiments with routine size crystals. The phase I beam line is not custom-made for microdiffraction. However, often NE-CAT users bring small crystals, with maximum dimension less than 30 microns. Some of these crystals result in diffraction data/structure and some do not. We foresee that soon an increasing number of our users will be routinely bringing such smaller crystals to the NE-CAT beam lines. The success of such experiments with smaller crystals could be greatly enhanced by optimizing the beam line components so that, a) smaller samples could be easily visualized, b) small beam could be crafted to match the size of sample and c) back ground scatter could be reduced. With these facts in mind, we have assessed development of a microdiffraction capability in house using a APS designed goniometer with a sphere of uncertainty of substantially less than 2 microns, developing a high-magnification co-axial sample imager, and upgrading the beam optics to provide a clean micro focus. Though it is feasible, it could be time consuming undertaking as our technical staff is focusing on construction of Phase II beam line. Therefore, in order to provide microdiffraction capability to NE-CAT users on the earliest time scale possible, we have decided to purchase a unit commercially. We have made an award to ACCEL to acquire the MD2 microdiffractometer manufactured by Maatel. The design for this microdiffractometer originates from the European Molecular Biology Laboratory (EMBL), units of which are being successfully used at the ESRF and SLS. With this microdiffractometer, we expect to be able to routinely study crystals with dimensions of a few microns using beams tailored to similar dimensions in order to reduce scattering contamination and backgrounds. Ours will be the first such unit operating in the US. Delivery is expected during September 2006, the scheduled APS maintenance shut down period. The MD2 will be initially installed on the Phase II beam line so that both the beam line and the MD2 can be commissioned at the same time, not impacting the Phase I user program. We expect to offer early user time on MD2 during late 2006.