DETECTOR DEVELOPMENT AND UPGRADE

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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. Objectives The objectives stated for 2008 renewal of this grant were these: upgrade our two existing Area-Detector Systems Corp. (ADSC) Q315 detectors, initiate the purchase of a modern pixel-array detector (PAD) that is at the state of the art, contribute to and participate in a detector-development program (monolithic, highly-integrated modules). Although they were favorably reviewed, initially we did not receive funding for the last two projects. During this year the NCRR provided a supplement to fund the PAD detector; the detector-development project is still not funded. An additional objective added last year was to obtain a quicker and larger detector to replace the aging Q4r currently in use at X26-C. We managed to borrow a larger and faster one: a Q210 owned by the NSLS and previously at X6-A. We'll soon replace it with the Serial #6 ADSC Q315 recently retrieved from X25. Results  The Pilatus P6M area detector ordered last year from Dectris AG of Baden Switzerland, and paid for with a NCRR supplement, arrived in Feb and was in place at beamline X25 and operating by 1 March 2011. Since that time 32 groups have used it, and have recorded over 100,000 degrees rotation of data. The standard mode of operation is to measure diffraction images in a continuous sweep, with the shutter remaining open and the 3.6ms deadtime being ignored. Note that at X29 data are taken with typical exposure rates of 2 sec/degree of rotation for one-degree images. The beam intensity is about the same, but at X25 the average is 5 sec/degree with 0.5deg. images. We attribute the longer exposure time to the greater difficulty of problems addressed at X25, which is set up for producing an especially small x-ray beam and does not yet have its automounter installed. Plans  We find that, as specified, the P6M is a single-photon-counting, essentially noise-free detector. The expected performance specifications are in the table above. It should be about 80% efficient for 1¿ x-rays. There are several data-reduction programs available for use with this detector. HKL2000 is the standard for other detectors and is the fall-back software for most users. Investigators are getting data that appear to be at least as good as were obtained from the previous CCD-based detector. At the same time that we are exploring how the large size, low noise, and potential for fast framing (up to 10 frames/sec) can give measurably better data with weakly diffracting crystals that have been possible before. Significance  We are in position to exploit the very best diffraction that a crystal can produce at NSLS with the instruments we have in place now. This detector will serve us as we move into NSLS II where we might expect in early days to be collecting data ten to twenty times as quickly.