Users' Conference Digs In
Friday, October 17, 2008
Day 3 of the LCLS / SSRL users' conference was devoted to separate workshop sessions for both groups. Discussion centered on cutting edge instrumentation and experimental techniques. The LCLS is at an early stage yet in the evolution of its scientific programs, and the majority of today's talks were conceptual, such as one workshop devoted to the theoretical challenges associated with what, exactly, the X-ray beam will do to matter. Add to that a few awards, a poster session and plenty of mingling, and you have yourself a conference.
I spent more time on the SSRL side of the party today, with special attention to the afternoon sessions describing the suite of new beamlines. Several are being built, with beamline 13 cranking into full swing, 4 taking shape, and 14 still in the planning stages. I wrote in detail about 13 here. It's surely obvious to the average scientist, but I am always struck by the ingenuity of some of these experimental devices, each intended to bring X-rays onto some specially prepared sample and then to measure what comes out. Simple in principle, but often mindbendingly complex in practice. And more to the point, the "what comes out" part is what makes lightsource science such a Swiss-army-knife of a tool. The "scanning transmission x-ray microscope" (STXM) instrument at 13.1, for example, sends in X-rays, and gets out X-ray photons, electrons, and fluoresced photons. All three of those can be collected and characterized. Plus, the incoming X-ray beam is focused into a tiny spot just a few microns across, and can be scanned around a sample. This adds up to a super high resolution map of the chemistry or molecular structure of materials. While the LCLS is certain to break new scientific ground, it is but a single avenue in the onward march of lightsource science. As a high "peak brightness" machine, the LCLS can throw a hugely powerful pulse of X-rays onto a sample in an unimaginably short amount of time. But, as high "average brightness" machines, synchrotron lightsources provide a (nearly) continuous stream of very bright X-rays that can be scanned over a sample, or made to gently "tickle" a sample without damaging it. SLAC and SSRL are eager to secure their scientific future along both fronts, with early stage plans in the works to build another, larger "ultimate" synchroton at the lab. Free electron lasers like the LCLS will surely proliferate in the coming years. But in terms of number of users and experiments, the future of lightsource science, because of the huge variety of experiments available using a synchrotron, will always lie much more heavily on the synchrotron side of things.* *The four operational lightsources under DOE collectively had 8,500 users in 2007. posted by Brad Plummer @ 6:00pm
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