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In this issue:
From the Acting Director of SSRL: Where do we go from here?
Water Motions Revealed
SciDAC Comes to SLAC

SLAC Today

Friday - May 21, 2010

From the Acting Director of SSRL:
Where do we go from here?

(Photo - Piero Pianetta)

As with other scientific facilities, the Stanford Synchrotron Radiation Lightsource faces an ever-changing landscape of experimental requirements, as a result of changing national needs and discoveries that direct the focus of its extensive user communities into new directions. These new research directions give rise to opportunities as well as challenges to further develop SSRL's capabilities. These challenges are met by the technical staff throughout SLAC who push the accelerator and beamlines to new performance levels. As is often the case in science, these new technical capabilities will in turn push scientific users to come up with new experimental ideas.

Since its commissioning in 2004 as a third generation synchrotron facility, SSRL has been undergoing a process of continuous improvements, with reductions in emittance, increases in current as well as upgrades of all of its beamlines with higher performance monochromators, state-of-the-art detectors and new types of end stations too numerous to mention in a short article. In spite of all these advancements, the question that never goes away is: where do we go from here? To answer this question, we in SSRL management have been developing a strategic plan that looks forward at least five years to guide our thinking.  Read more...

(Photo)
Kelly Gaffney (left) and Minbiao Ji in their laser lab. (Photo by Brad Plummer.)

Water Motions Revealed

Gaze into a glass of water, and you're unlikely to see much more than your own reflection. But gaze a little deeper using a microscope—or, better yet, a series of laser pulses and detectors—and you'll see an intricate molecular dance. As water sits, seemingly calm, the hydrogen bonds between water molecules are continually breaking and forming, with each molecule switching dance partners a hundred billion times a second.

"We've known for quite a while that the hydrogen bonds change constantly, but the details were still fuzzy," said Kelly Gaffney, a researcher at the joint SLAC–Stanford PULSE Institute for Ultrafast Energy Science. "In recent simulations, others have found that the switch from one bond to another happens very quickly, and that the angle between the hydrogen atom bonds changes by 60 or 70 degrees. But it's so hard to simulate the complex nature of water that it was important to check this prediction experimentally."

Now, in collaboration with Stanford physics graduate student Minbiao Ji and Stockholm University chemical physicist Michael Odelius, Gaffney has conducted intricate experiments showing that the molecules do indeed act as simulations predict. 

Read more and see the animation...

SciDAC Comes to SLAC

SciDAC attendees in front of Kavli Auditorium.
(Photo by Julie Karceski.)

The SciDAC Computational Astrophysics Consortium held its annual meeting at SLAC this week. The group, which is made up largely of astrophysicists and computer coders, uses computers to model supernovae. They gathered in the Kavli Auditorium May 19-21 to share developments and discuss what's on the horizon.

"We use the largest computers in the world to make 3-D models of exploding stars," said Stan Woosley, a physicist from UC Santa Cruz and a co-organizer of the event.

SciDAC is an abbreviation for Scientific Discovery through Advanced Computing. This Department of Energy-funded project spans many scientific disciplines. Launched in 2001, SciDAC began as a computing resource for researchers in energy sciences, biological and environmental research, fusion energy sciences, and high-energy and nuclear physics. Around 50 members of the Computational Astrophysics Consortium attended this week's event, representing eight government labs and universities.

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