CONSTRUCTION STARTS ON GROUNDBREAKING LASER

乏味 · 发表于 2006-10-24 18:41:00

Physicists at Stanford's Linear Accelerator Center abandoned their laboratories Friday morning for a joyful celebration with state and federal dignitaries of the groundbreaking for the world's first X-ray laser, expected to attract research scientists from around the world.

``This machine represents leadership in the world of science,'' said Raymond Orbach, undersecretary for science with the U.S. Department of Energy, amid dust, cranes and hard hats. He was joined by Reps. Anna Eshoo, Zoe Lofgren and Mike Honda.

The $379 million laser, the latest and grandest addition to the quickly changing SLAC campus in the Palo Alto hills, will create an ultra-fast and ultra-bright light source that makes it possible for scientists to watch matter in action -- one molecule at a time.

With ceremonial shovels, the officials dug a small hole that marks the beginning of what will become a 180,000-cubic-yard excavation site.

Entertainment was provided by the Stanford Band, whose musicians donned hard hats, lab coats and other colorful costumes.

The site for the Linac Coherent Light Source (LCLS), which will feature much new lab space as well as a half-mile extension of SLAC's tunnel, is to be completed in two years, with research starting in 2009.

Just as Eadweard Muybridge's fast-shutter photos captured the motion of Leland Stanford's trotting horse, this new X-ray will freeze the motion of atoms in time, said Stanford Provost John Etchemendy.

``It will allow us to see processes and phenomena that cannot stand still -- the molecular counterpart of Stanford's horse,'' Etchemendy said.

It is the newest tool in the field of photon science, one of the most rapidly expanding fields of physics.

Synchrotrons, once unique, are now almost commonplace around the world. And the X-ray pulses that they provide, although fast, are not quite fast enough. Capturing an image of an electron at work is like trying to photograph a speeding bullet with an old box camera.

The new LCLS facility will emit X-ray pulses 1,000 times shorter and 10 billion times brighter than pulses from SLAC's current synchrotron.

It will use the end of the existing accelerator to send bunches of electrons hurtling down the tunnel to generate pulses of X-ray light.

These electrons will then speed through a slalom course of magnets known as undulators. The magnets will force the electrons to zigzag -- and every time an electron changes direction, it emits X-ray radiation. Because of the ultra-high speed, the X-ray radiation will have the characteristics of a laser.

The bursts of light -- orders of magnitude brighter than any other existing light source -- will enable researchers to film at atomic detail the precise sequence of events in chemical reactions and biological processes.

``Reactions will be frozen in time, like dancers in a stroboscopic light,'' Orbach said.

Facility director John Galayda said it will be possible, for instance, to directly observe molecules at the moment when new chemicals are formed, or to witness a single molecule in a process that is essential to life. It may even be possible to see atoms as they change states of excitation, he said.

This facility is predicted to bring SLAC to the frontier of atomic physics, chemistry, materials, fluids, plasmas and molecular biology, Etchemendy said.

``It opens a new set of eyes,'' he said.

The facility was conceived in 1993. Part of the Department of Energy's Basic Energy Sciences Program, it now has the strong support of President Bush, who has pushed for doubling federal funding for basic research in the physical sciences over the next 10 years.

The Bush administration has pinned its hopes on physics and related areas of nanotechnology, materials and high-speed computing to provide the underpinnings for advances in alternative fuels and other technologies.

URL:http://www.mercurynews.com/mld/mercurynews/news/local/states/california/the_valley/15814990.htm

CONSTRUCTION STARTS ON GROUNDBREAKING LASER

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