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LCLS—Creating a Revolution in X-ray Science

The second annual workshop on science with free-electron lasers, sponsored by the Max Planck Society, was held last week in the society's conference center at Schloss Ringberg in the Bavarian Alps south of Munich. This has become an annual, informal opportunity for researchers using Linac Coherent Light Source, FLASH and other facilities to meet for three days in an isolated mountain castle to discuss the problems and revolutionary opportunities of the new generation of X-ray laser light sources. The spectacular LCLS results just published last month in Nature on nanocrystallography and single-particle imaging of viruses were old news at this meeting, where the "buzz" was much more focused on the new data that has been collected since last summer. LCLS featured very prominently in many of the scientific presentations. These are the not-yet published results that will create headlines in the coming year. The talks were filled with images that were even more impressive than the snowy Alpine mountain scenery on view through the windows in the back of the lecture hall.

Jim Welch presented the current status of LCLS and future plans and vision for LCLS-II, and there were also talks on the status of the European XFEL and Spring-8 sources currently under construction. There were a number of other participants from SLAC, who presented several talks. John Bozek spoke about the LCLS Atomic, Molecular and Optical science instrument and recent results. Bill Schlotter described single-shot correction for timing jitter with soft X-rays. Christoph Bostedt talked about imaging ultrafast processes in clusters. Marco Cammarata gave an update on the first hard X-ray experiments at the X-ray Pump Probe instrument and one of us (Phil Bucksbaum) discussed recent AMO X-ray experiments in small molecules. The contingent of scientists associated with SLAC and LCLS experiments would likely have been even larger, except for ongoing LCLS experiments at the newly commissioned Coherent X-ray Imaging instrument.

Rather than summarize unpublished results, we should just take a few moments to give you the flavor of the meeting. Last year's euphoria over the world's first X-ray FEL laser source (LCLS) just producing its first results was replaced by something that is equally remarkable: a growing diverse community of scientists devoted to pushing the forefront of X-ray FEL research, sharing information to the mutual benefit of each other and the field. As many of the experiments are still in the "proof of principle" phase, this information sharing proves to be critical across a rapidly growing number of disciplines.

One of several themes that recurred in numerous talks concerns the need to handle massive amounts of data at LCLS. The large amount of information creates problems in data storage, sorting and processing; but it also creates new opportunities to dig into data sets to excavate signals that show how the electronic and structural properties of nanoparticles and macromolecules evolve under dynamic conditions on timescales from less than a femtosecond up to milliseconds.

We also saw the emerging importance of exotic ultrafast lasers coupled to the X-ray experiments, which can excite, orient or even blow up systems that the X-rays are probing. Last year's questions about whether precise timing is possible were replaced by this year's demonstrations of multiple techniques to achieve good pump-probe timing resolution with prospects for further improvements.

The early LCLS experiments have created a kind of international camaraderie that is very special for the development of new science at this facility. Many collaborations and connections are now being formed. Some will be formalized by agreements between institutions, but many more are simply collaborations between individuals for the benefit of the science. It's clear that we are witnessing a new community in the making, driving in directions that break completely new ground. There is every reason to believe that this community will be as robust and as impactful as the synchrotron communities that have grown up around SPEAR3 and the other international synchrotrons. It was truly an inspirational event and LCLS and the science it has enabled shone extremely brightly.

—Phil Bucksbaum, Photon Sciences Chemical Sciences Division and PULSE director;
   Keith Hodgson, Photon Sciences associate laboratory director
   and Uwe Bergmann, LCLS deputy director
SLAC Today, March 11, 2011