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In this issue:
Where the LCLS Ends: The CXI Instrument
Secretary Chu Joins with World Leaders to Sign International Partnership for Energy Efficiency Cooperation
The Mural a Half-mile Underground
Around SLAC: BuildingĀ 40's Respiratory System

SLAC Today

Tuesday - May 26, 2009

Where the LCLS Ends: The CXI Instrument

(Photo - CXI instrument team)
The CXI instrument team (from left): Armin Busse, Nat Stewart, Paul Montanez, Sebastien Boutet (foreground), Don Schafer, Bill Olson and Mike Bogan. (Photo by Brad Plummer.)

The Coherent X-ray Imaging instrument, the fourth scientific instrument to be installed at the Linac Coherent Light Source, will view single objects smaller than a micron, or one millionth of a meter—tiny. But even better than that, it may be the first X-ray instrument ever to do so for individual biological molecules when it comes online in 2011.

"Synchrotrons like the Stanford Synchrotron Radiation Lightsource are wonderful for imaging biomolecules that can be crystallized," said CXI Instrument Scientist Sebastien Boutet. "With the CXI instrument, we can hopefully for the first time use X-rays to view what can't be crystallized: individual biomolecules."

When researchers send synchrotron X-rays at a crystallized sample, the crystal's repeated molecular structure diffracts the X-rays in a regular pattern. This pattern can be sensed by detectors and analyzed to determine the sample's three-dimensional structure.

Unlike the beams from synchrotron sources, X-rays from the LCLS arrive at an instrument in extremely short and intense pulses that can resolve the structure of single molecules or small clusters. No repeated crystal structure is needed to amplify the signal.

Researchers can't put single, non-crystallized biological molecules in a synchrotron beam for another reason: the beam destroys the sample before sufficient signal can be measured. As X-rays travel through the sample, they knock electrons out of atoms, breaking important chemical bonds and modifying the structure of the sample during the measurement. Synchrotrons avoid this problem by spreading the power of the beam across billions of molecules, reducing the number of electrons expelled from each molecule.

The CXI instrument will solve this conundrum in another way.  Read more...

Secretary Chu Joins with World Leaders to Sign International Partnership for Energy Efficiency Cooperation

The Department of Energy announced Saturday that U.S. Energy Secretary Steven Chu joined with top energy leaders from around the world to launch the International Partnership for Energy Efficiency Cooperation. As part of the Group of 8 Energy Ministers Meeting in Rome this weekend, G8 members and other interested countries took steps to accelerate the implementation of energy efficient measures in their economies. IPEEC signatories included members of the G8—Canada, France, Germany, Italy, Japan, the Russian Federation, the United Kingdom, and the United States, and key emerging economies such as Brazil, China, India, Mexico and the Republic of Korea.

"This partnership can help lead the world toward greater energy efficiency," Secretary Chu said. "It will facilitate greater cooperation on our shared goals: a healthier planet and a stronger global economy."  Read more from the DOE...

The Mural a Half-mile Underground

(Image - the mural)
Minnesota artist Joseph Giannetti painted this mural on the rock wall near the MINOS detector. (Photo: Symmetry Breaking)

It seems unnecessary to put windows in an office located half a mile underground. But even if the employees of the Soudan Underground Laboratory cannot watch the clouds roll by as they sit at their desks, many of them gaze through the blinds at a color-soaked 25-by-60-foot mural painted on the rock wall.

An old ore mine in northern Minnesota houses the laboratory, home to the detector for the Main Injector Neutrino Oscillation Search experiment. Minnesota artist Joseph Giannetti created the mural, which represents the laboratory’s work. He stood on a window-washer’s platform and painted while others pieced together the detector below, said Soudan Mine Assistant Lab Manager Jerry Meier.

"In order to make everything look right because the rock is so rough, he had to use a projector to project his image on the rock," Meier said. "Then he would paint on it and move the projector over and paint another part."  Read more in Symmetry Breaking...

Around SLAC: Building 40's Respiratory System

(Photo - atop SLAC's Building 40)
(Photo by Lauren Schenkman.)

Contemporary art installment or physics experiment? The answer is neither. It may not be obvious at first glance, but this maze is made up of the air ducts, water pipes and electrical lines that handle the cooling, heating and recycling of air for Building 40's many temperature-controlled zones.

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