Transmission X-Ray Imaging Detector Captures the Last Light at NSLS

Biological research constitutes a large and expanding scientific focus at synchrotron facilities. Structural biology researchers using x-ray facilities make up the majority of this community, including use of techniques such as macromolecular x-ray crystallography, small-angle x-ray solution scattering, x-ray microscopy, x-ray absorption spectroscopy, x-ray fluorescence and x-ray footprinting. Many of these technologies, as they are developed to take advantage of next-generation synchrotron sources, are trending toward use of high flux beams and/or beams which require enhanced stability and precise understanding of beam position and intensity from the front end of the beamline all the way to the sample. For high flux beams, major challenges include heat load management in optics (including the vacuum windows) and a mechanism of real-time volumetric measurement of beam properties such as flux, position, and morphology. For beam stability in these environments, feedback from such measurements directly to control systems for optical elements or to sample positioning stages would be invaluable. For x-ray footprinting, a focused “white beam” is used to maximize x-ray flux density over a practical sample size using a toroidal mirror. This intense beam can melt beryllium windows and is very complicated to measure, causing difficulties with properly focusing the mirror and with understanding where the beam is and exactly what is being delivered to the sample. To address these challenges, we are developing diamond-based instrumented vacuum windows with integrated volumetric x-ray intensity, beam profile and beam-position monitoring capabilities. The prototype device will be used as the exit window for the XFP beamline currently being developed at NSLS-II for x-ray footprinting. Current progress is presented, including successful demonstration of a >1kilopixel free-standing transmission imaging detector that was used to capture the last x-ray photons at the National Synchrotron Light Source.