LELAND STANFORD JUNIOR UNIVERSITY, THE

Title: LCLS Ultrafast Science Instruments MIE (LUSI Acceleration) Purpose: Specifically, this funding is to accelerate progress on the LUSI project as compared to its already approved project baseline plan. For more detailed information, see Contract Work Authorization Number KC/OR55/9, Revision Number 02, dated 3/31/09. Description: The LCLS Ultrafast Science Instrumentation (LUSI) project will provide three of the six experimental instruments that will use the unique X-ray capabilities of the Linac Coherent Light Source to study the ultrasmall and the ultrafast. Scheduled to begin operations between 2010 and 2012, these three instruments will take advantage of the LCLS's unprecedented ability to produce ultrashort pulses of high-energy or "hard" X-ray laser light. These instruments are the X-ray Pump Probe instrument, the Coherent X-ray Imaging instrument and the X-ray Correlation Spectroscopy instrument. X-ray Pump Probe Instrument The XPP instrument will use a fast optical laser to generate transient states of matter, then use the hard X-ray pulses from the LCLS to probe the structural dynamics initiated by the laser excitation. The initial, ultrafast laser pulse excites a brief change in the positions of the atoms in the sample. This change is then studied using scattering of the LCLS X-ray pulse, which follows the first laser pulse after a precise time delay. Coherent X-ray Imaging Instrument The Coherent X-ray Imaging instrument will take advantage of the extremely bright, ultrashort LCLS pulses of X-rays to image nano-scale objects, including single biomolecules or small clusters of them, at or near atomic resolution. In combination with the LCLS, coherent X-ray imaging can potentially provide a new horizon of imaging nano-scale materials and biological materials such as viruses and large single biomolecules at or near atomic resolution in three dimensions. Resolution in these experiments would not depend on sample quality in the same way as in conventional imaging methods, but would be a function of the LCLS's outstanding X-ray beam intensity, short pulse duration and high-energy wavelength. The penetration depth of hard X-rays in combination with the coherent, laser light will permit detailed 3-D study of molecules and provide capabilities that will go beyond current approaches such as scanning probe microscopy, electron microscopy or X-ray crystallography. X-ray Correlation Spectroscopy Instrument The unprecedented brilliance, narrow pulse duration and advanced laser properties of the LCLS provide a unique opportunity to observe dynamic changes in large groups of atoms over a wide range of time scales, using a technique called X-ray Photon Correlation Spectroscopy. In contrast to the laser-excitation approach of X-ray pump-probe experiments like the XPP, the XCS technique studies molecular fluctuations caused by the heat energy of the sample itself. XCS takes mages of the scattering patterns caused when the LCLS X-rays are diffracted by the sample; images taken with different delay times provide a stop-motion view of sample molecules in motion. The brilliant laser light and short pulse lengths produced by LCLS will allow scientists to use this approach to view much more weakly-scattering samples, compared to previous approaches, and to much faster time scales, from femtoseconds to mere nanoseconds. Deliverables: 1. Execution Phase, CD-3 approve start of construction (April 2010) 2. Closeout Phase, CD-4 approve star of operations (February 2012)

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