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In this issue:
Researchers Rediscover the Structure of Water
Ribbon Cutting for the LCLS Far Experimental Hall

SLAC Today

Tuesday - February 23, 2010

Researchers Rediscover the Structure of Water

Researchers at SSRL recently determined the distances between the molecules in this jet of flowing water. (Image courtesy the research team.)

A team of researchers at the Stanford Synchrotron Radiation Lightsource has found the molecular structure of water to be more complex than recently thought, suggesting that molecular models that went out of fashion decades ago may be in fact more accurate than recent ones.

"The study of water has a very long history," said lead author Ling Fu, who is a postdoc at the Centre National de la Recherche Scientifique in France and who wrote her PhD thesis on these results. "Other researchers have done a very good job in their measurements; I hope that this work helps advance the field."

By recording how SSRL's X-ray beam scattered off a flowing jet of water, Fu and colleagues Arthur Bienenstock and Sean Brennan were able to determine the distances between the water molecules in the jet. As recent models predicted, they saw molecules 0.28 and 0.45 nanometers apart. These measurements confirm the current commonly accepted model, which describes liquid water as a group of water molecules held together in tetrahedral shapes, with the molecule at the center of the tetrahedron separated from four others at the shorter distance and each of these four molecules separated from one another at the longer distance.  Read more...

Ribbon Cutting for the
LCLS Far Experimental Hall

(Photo - ribbon cutting at the LCLS Far Experimental Hall)
Uwe Bergmann (right), holding the symbolic wooden "key" to the FEH, addresses the crowd at the ribbon cutting ceremony. (Photo by Julie Karceski.)

A hearty congratulations to everyone involved the creation and construction of the Linac Coherent Light Source Far Experimental Hall. Yesterday, the FEH officially opened with a ribbon cutting ceremony and handing over of the official FEH "key" to LCLS Deputy Director Uwe Bergmann. SLAC employees from various stages of development were on hand to enjoy cake and tour Hutches 4, 5 and 6.

(Photo - ribbon cutting at the LCLS Far Experimental Hall)
David Saenz (left) and John Galayda open the LCLS's Far Experimental Hall during the ribbon cutting ceremony. (Photo by Julie Karceski.)

The long haul of the LCLS project is nearly complete, with exception of nearby office space. First suggested at SLAC in the early 1990s, the LCLS received a green-light from the Department of Energy in 2001 and funding to begin construction in 2005. John Galayda, the head of LCLS construction, said the LCLS is an unusual project because experiments began before the entire facility was finished.

"It's as much of a thrill as anything, to know that it's already working," he said. Galayda credited support from the whole SLAC organization and the DOE for helping with the successful fruition of LCLS.

"This is the product of a lot of thought and creativity," he said. "Everyday I'm aware of how carefully and creatively the work is done in every area of LCLS—the physics, the engineering, the civil construction planning and execution, the controls, the conduit and cable routing, the safety planning, the procurement and contract management—everything."


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