The first experiments are now underway using the world's most powerful X-ray
laser, the Linac Coherent Light Source, located at the Department
of Energy's SLAC National Accelerator Laboratory. Illuminating objects and
processes at unprecedented speed and scale, the LCLS has embarked on groundbreaking
research in physics, structural biology, energy science, chemistry and a host
of other fields.
 | | The AMO instrument scientists with the first LCLS users in the instrument hutch. From left to right: Christoph Bostedt, Steve Southworth, Linda Young, John Bozek, Steve Pratt and Yuelin Li. (Image courtesy of Brad Plummer, SLAC. |
In early October, researchers from around the globe began traveling to SLAC
to get an initial glimpse into how the X-ray laser interacts with atoms and
molecules. The LCLS is unique, shining light that can resolve detail the size
of atoms at ten billion times the brightness of any other manmade X-ray source.
“No one has ever had access to this kind of light before," said
LCLS Director Jo Stöhr. “The realization of the LCLS isn’t
only a huge achievement for SLAC, but an achievement for the global science
community. It will allow us to study the atomic world in ways never before possible.”
The LCLS is a testament to SLAC’s continued leadership in accelerator
technology. Over 40 years ago, the laboratory’s two-mile linear accelerator,
or linac, was built to study the fundamental building blocks of the universe.
Now, decades later, this same machine has been revitalized for frontier research
underway at the LCLS.
After SLAC’s linac accelerates very short pulses of electrons to 99.9999999
percent the speed of light, the LCLS takes them through a 100-meter stretch
of alternating magnets that force the electrons to slalom back and forth. This
motion causes the electrons to emit X-rays, which become synchronized as they
interact with the electron pulses over their long slalom course, thereby creating
the world’s brightest X-ray laser pulse. Each of these laser pulses packs
as many as 10 trillion X-ray photons into a bunch that's a mere 100 femtoseconds
long—the time it takes light to travel the width of a human hair.
Currently, user-assisted commissioning is underway, with researchers conducting
experiments using the Atomic, Molecular and Optical science instrument, the
first of six planned instruments for the LCLS. In these first AMO experiments,
researchers are using X-rays from the LCLS to gain an in-depth understanding
of how the ultra-bright beam interacts with matter.
Early experiments are already revealing new insights into the fundamentals
of atomic physics and have successfully proven the machine’s unique capabilities
to control and manipulate the underlying properties of atoms and molecules.
Earlier this month, researchers used the LCLS's strobe-like pulses to completely
strip neon atoms of all their electrons. Researchers also watched for two-photon
ionization—an event where two photons pool their energy to eject a single
electron from an atom. Normally difficult to observe at X-ray facilities, researchers
at the LCLS were able to study these events using the extreme brightness of
the laser beam.
Future AMO experiments will create stop-action movies of molecules in motion.
The LCLS's quick, short, repetitive X-ray bursts enable researchers to take
individual photos as molecules move and interact. By stringing together many
such images to make a movie, researchers will for the first time have the ability
to watch the molecules of life in action, view chemical bonds forming and breaking
in real time, and see how materials work on the quantum level.
By 2013, all six LCLS scientific instruments will be online and operational,
giving researchers unprecedented tools for a broad range of research in material
science, medicine, chemistry, energy science, physics, biology and environmental
science.
“It’s hard to overstate how successful these first experiments
have been,” said AMO Instrument Scientist John Bozek. “We look forward
to even better things to come.”
For additional information, please see the LCLS Web site, image gallery, video,
and animation.
The Linac Coherent Light Source is a DOE Office of Science-funded project led
by SLAC National Accelerator Laboratory. SLAC has executed the project in partnership
with Argonne National Laboratory and Lawrence Livermore National Laboratory.
In addition, Pacific Northwest National Laboratory provided project management
support. Lawrence Berkeley National Laboratory and Cornell University have contributed
key subsystems. University of California, Los Angeles has provided theoretical
physics support throughout the project; Brookhaven National Laboratory and Los
Alamos National Laboratory were active in the early stages of LCLS research
and development.
SLAC National Accelerator Laboratory is a multi-program laboratory exploring
frontier questions in photon science, astrophysics, particle physics and accelerator
research. Located in Menlo Park, California, SLAC is operated by Stanford University
for the U.S. Department of Energy Office of Science.
Posted November 2nd, 2009
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