MICRODIFFRACTION AT THE NE-CAT BEAMLINES

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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.