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. Objectives The major project during this year was to perform the major step in the upgrade of X25 by replacing the original wiggler with a mini-gap undulator. Optical elements will be upgraded to match the capabilities of the source. We will continue to operate X25 for users. Results There has been significant progress on the major upgrade to the wiggler beam line X25, the capital costs for which have been borne mostly by our BER-DOE funding. During the December 2005 shutdown, we replaced the wiggler source with a mini-gap undulator, similar to but improved with respect to the one that is the source for X29. Instead of being 340mm long with a 12.5mm period and 3.3mm minimum gap, this undulator is 950mm long with an 18mm period and 5.6mm minimum gap. This will increase the brightness of this beam line by a factor of three to five, and will fill in the 9-11keV region that is very weak at X29. The new monochromator and mirror have been ordered and will be installed during this next grant period. We anticipate operating under full focusing by Feb 2007. We have ordered an upgrade to the existing diffractometer, funded by BER-DOE. The modifications will include replacement of the current old-style three-axis orienter with a high-speed (air-bearing servo motor) ? axis, motorized three-axis goniometer head, and a miniature ?-f orienter on top of that. This upgrade will be installed during the May 06 shutdown and will leave the diffractometer ready for a robotic automounter. The experimental station is being refurbished with new routing for control cables and more descriptive visual displays. At the time of writing, we are able to take data with a beam that is much improved in collimation. We are patiently improving alignment of all components of the system to bring it to its design brightness. Operations for PX continue to occupy essentially all of the beam line s available time. X25 continues to benefit from the PX Operators who have been employed to work nights and weekends to assist users. Ninety-six PDB submissions were recorded for the beam line in calendar 2005. This compares quite favorably with values from Advanced Photon Source undulator beam lines which are 20-50 times brighter than X25 has been: the highest APS values are 172 for the Structural Biology Center and 110 for the South-East Regional CAT. Plans We are responding to the intense need within the community we serve to be able to perform diffraction studies on very small crystals. We are beginning discussions on how best to provide micro-crystal diffraction capability at X25 during this year. We imagine that X25 will continue to be the site for very difficult projects, complementing the high-throughput emphasis at X29. Significance With the emergence of beam line X29 as the hottest source suitable for PX at the NSLS, the upgrade of X25 has become the project of the moment. It will begin to fill an important niche with work on the smallest specimens, and ones that will exploit the especially high brightness of the new undulator at lower energies. During the last year, the numbers of publications and PDB submissions is very impressive for any beam line anywhere.
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