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In this issue:
Imaging in a FLASH: Scientists Capture First-ever X-ray Laser Image Using a Single, Ultra-fast Shot
Dorfan Today: A Game of Jacks
symmetry: the Particle Pocket Card
Safety First

SLAC Today

Monday - November 13, 2006

Imaging in a FLASH: Scientists Capture First-ever
X-ray Laser Image Using a Single, Ultra-fast Shot

Researchers zapped the sample (left) with a single, 25 femtosecond pulse from the DESY soft x-ray free-electron laser to obtain a diffraction pattern (center). The sample, a 20-micrometer-wide square of silicon nitride film, was destroyed by the laser pulse, but a special computer algorithm processed the diffraction pattern in the center image to reconstruct the original image (right). (Click on image for larger version.)

Researchers have for the first time used an extremely short and intense x-ray laser pulse to successfully obtain a high-resolution image of a nano-scale object before the laser destroyed the sample. The experiment, conducted at Deutsches Elektronen-Synchrotron (DESY) in Hamburg by a collaboration that included researchers from SLAC, also set a speed record of 25 quadrillionths of a second (25 femtoseconds) of the duration of the x-ray pulse used to acquire the image. The results are published in the November 12 online edition and the December print edition of Nature Physics.

"This result is a remarkable validation of the concept of imaging using single pulses from a free electron laser," said Keith Hodgson, Director of Photon Science at SLAC and a co-author of the paper. "This is just the first glimpse of the breakthrough discoveries that will come from the Linac Coherent Light Source (LCLS) when it becomes operational in 2009." Read more...

(Director's Column - Dorfan Today)

Playing Laser Jacks

Almost everyone has played the game of Jacks at sometime in his or her life. You throw the ball in the air and have to snatch up the five jacks before the ball hits the ground. You have little time and if you are too slow or too clumsy—you lose! Getting science data from the Linac Coherent Light Source (LCLS) will be much the same: speed and technique will be everything.

When the LCLS comes online in 2009, it will be among the most powerful x-ray instruments ever built. And yet it is the very power of this new laser that is presenting some of the most profound research challenges. When focused tightly, the intense laser beam will almost immediately destroy many of the samples it shines on. Can useful data be recorded before a sample is vaporized? Now, thanks to recent collaborative research by scientists at Lawrence Livermore National Laboratory (LLNL), Uppsala University, SLAC, Deutsches Elektronen-Synchrotron (DESY) in Hamburg and several other institutions, an important step toward clearing this hurdle has been taken. We now have experimental evidence that we can get the jacks before the ball falls.  Read more...

symmetry Deconstructs
the Particle Pocket Card

(Image - Particle Pocket Card)
In the early 1950s, Nobel-Laureates-to-be Norman Ramsey and Ed Purcell created cards of physical constants they found themselves using most frequently. A few months later, an Addison-Wesley publisher's representative handed Ramsey a card filled with trivia. Ramsey responded, "Why don't you give out something people really want?" The pocket table was born.

Harvey Lynch paid about fifty cents for his table when he was an undergraduate at MIT. Forty years later, now at SLAC, he still carries it. "I was always using it to find some constant," Lynch says. "Of course, it would come up in the wrong unit and I would have to convert it." Read more...

Safety Firsts

The Concorde airliner crashed in Paris in 2000 due to the fire from a massive fuel leak melting the flight control surfaces causing the plane to fall out of the sky. Yet this accident was entirely preventable. Do you know how?

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