MICRODIFFRACTION AT THE NE-CAT BEAMLINES

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目及 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 人们越来越需要配备用于对小于20-30微米的晶体进行衍射实验的同步加速器光束线。NE-CAT的第一阶段光束线已经证明了光束线组件的稳定性，可以为常规尺寸晶体的晶体学实验提供稳定的聚焦X射线束。相位I光束线不是为微衍射定制的。然而，NE-CAT用户通常会带来最大尺寸小于30微米的小晶体。这些晶体中的一些产生衍射数据/结构，而一些不产生。我们预计，很快就会有越来越多的用户将这种更小的晶体带到NE-CAT光束线上。通过优化射束线组件，可以极大地提高这种具有较小晶体的实验的成功率，使得a）可以容易地观察较小的样品，B）可以制作小射束以匹配样品的尺寸，以及c）可以减少后向地面散射。 考虑到这些事实，我们已经评估了微衍射能力的发展，在内部使用APS设计的测角仪与球的不确定性大大小于2微米，开发一个高放大率的同轴样品成像仪，并升级光束光学提供一个干净的微焦点。虽然这是可行的，但由于我们的技术人员正专注于第二期光束线的建设，这可能是一项耗时的工作。因此，为了尽早向NE-CAT用户提供微衍射能力，我们决定购买一台商业设备。我们已与ACCEL签订合同，购买Maatel生产的MD 2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。有了这种微衍射仪，我们希望能够使用定制为类似尺寸的光束来常规研究尺寸为几微米的晶体，以减少散射污染和背景。我们将是第一个在美国运营的此类单位。预计在2006年9月，即计划的APS维护关闭期间交付。MD 2最初将安装在二期射束线上，以便射束线和MD 2可以同时调试，而不会影响一期用户程序。我们希望在2006年晚些时候提供MD 2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.