From Symmetry: “SLAC’s historic ‘End Station A’ hosts electron beams again”

April 26, 2013
Mike Ross

A new facility opens for experiments this week in SLAC’s historic End Station A, where the first evidence for quarks was discovered.

Electrons are once again streaming into SLAC’s End Station A, setting the stage for a new facility in the huge, concrete hall where the first evidence for quarks was discovered.

It was there that a research team including SLAC and MIT physicists used SLAC’s electron beam to discover that protons in the atomic nucleus were composed of smaller entities called quarks. That research led to the 1990 Nobel Prize in Physics.

The new facility, called the End Station Test Beam, will host experiments that test detector parts and experiments that will aid in the design of a proposed international linear collider project.

ILC

The first experiment, which will be carried out by SLAC researchers as part of the commissioning process, is being installed this week. The first outside users are expected to arrive in about a month.

Researchers will use a new beamline fed by billion-particle bunches of high-energy electrons diverted from the laboratory’s Linac Coherent Light Source. LCLS uses the energetic electrons to create a powerful X-ray laser beam for research that reveals unprecedented detail on the atomic scale.”

See the full article here.

Symmetry is a joint Fermilab/SLAC publication.

From SLAC: “Novel Analysis Method Levels the Quasar Playing Field”

April 18, 2013
Lori Ann White

“In the nearly six decades since quasars were discovered, the list of these energetic galaxies powered by supermassive black holes has grown to more than 100,000 – enough examples to reveal important information about the quasar population as a whole. But attempts to conduct a celestial census of these powerful objects have been limited by a fundamental problem: Although quasars are bright, they also span billions of light years in distance from Earth. Just as with stars in an urban sky, the closest quasars can be seen even if they are dim, while the oldest and most distant ones can be seen only if they are bright. This means astrophysicists have to study a sample with big differences among individual members, including distance, age, brightness and type of radiation emitted.

The interaction of a supermassive black hole and a disk of accreting matter, called a quasar, can be seen at the center of a faraway galaxy in this artist’s concept. It consists of a dusty, doughnut-shaped cloud of gas and dust that feeds a central supermassive black hole. As the black hole feeds, the gas and dust heat up and spray out different kinds of light, as illustrated by the white rays.

Astrophysicists with the Kavli Institute for Particle Astrophysics and Cosmology, a joint SLAC-Stanford institute, found a way to reach past these limitations: They improved an algorithm that homes in on important commonalities of a population of objects while taking into account the limitations and biases for observations made in multiple types of electromagnetic radiation, such as optical light or radio waves – two of the most important wavelengths for studying quasars.

In the process they shed new light on a contentious question: Are there two types of quasars, with one “louder” in radio than the other, or is there just one type with emissions that vary widely across the electromagnetic spectrum?”

See the answers in the full article here.

SLAC 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 DOE’s Office of Science.

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From SLAC Lab: “Producing X-ray Laser Pulses in Two Colors”

March 26, 2013
Glenn Roberts Jr.

“SLAC researchers have demonstrated for the first time how to produce pairs of X-ray laser pulses in slightly different wavelengths, or colors, with finely adjustable intervals between them – a feat that will allow them to watch molecular motion as it unfolds and explore other ultrafast processes.

Left to right: SLAC scientists Yuantao Ding, Alberto Lutman and Ryan Coffee, shown here at SLAC’s Main Control Center, participated in successful experiments that created two closely spaced X-ray pulses of slightly different X-ray wavelengths using a combination of separately tuned undulators and a magnetic chicane that serves to delay electron bunches from SLAC’s linac. (Credit: Matt Beardsley)

This technique, reported March 25 in Physical Review Letters, could open up a new realm of experiments at SLAC’s Linac Coherent Light Source (LCLS), potentially revealing how bonds between atoms form, break and rearrange and how atoms absorb light on ultrafast time scales of less than 25 femtoseconds, or quadrillionths of a second. Each of the paired X-ray laser pulses can be tuned to study a specific element in atomic detail, and they can be timed to hit a sample nearly simultaneously.

‘The LCLS really is evolving faster than the science can keep up,” said Ryan Coffee, one of the lead authors on the paper. “This really showcases its amazing flexibility.’”

See the full article here.

SLAC 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 DOE’s Office of Science.

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From SLAC: “X-ray Laser Explores How to Write Data with Light”

March 19, 2013
Glenn Roberts Jr.

“Using laser light to read and write magnetic data by quickly flipping tiny magnetic domains could help keep pace with the demand for faster computing devices.

A look inside the RCI sample chamber while researchers close up the chamber for vacuum for an experiment at LCLS. (Credit: Diling Zhu/SLAC)

Now experiments with SLAC’s Linac Coherent Light Source (LCLS) X-ray laser have given scientists their first detailed look at how light controls the first trillionth of a second of this process, known as all-optical magnetic switching.

The experiments show that the optically induced switching of the magnetic regions begins much faster than conventional switching and proceeds in a more complex way than scientists had thought – a level of detail long sought by the data storage industry, which is eager to learn more about the key drivers of optical switching. The new insight could help guide efforts to engineer materials that better control and speed this process.

Group photo of researchers who participated in an all-optical magnetic switching experiment at the Linac Coherent Light Source. (Credit: SLAC)

http://www6.slac.stanford.edu/pictures/220×142-(news-article-main)/130319-nanoswitching-art-thumb.jpg

‘This is really one of the first examples of new materials science that can be done with LCLS, which allows you to look at very short time scales and very small length scales,’ said Hermann Dürr, a staff scientist for the Stanford Institute for Materials and Energy Sciences (SIMES) and a principal investigator of the multinational team that performed the experiment, detailed in the March 17 issue of Nature Materials. SIMES is a joint institute of SLAC and Stanford.”

See the full article here.

SLAC 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 DOE’s Office of Science.

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From SLAC: “Materials Scientists Make Solar Energy Chip 100 Times More Efficient”

March 19, 2013
Mike Ross

“Scientists working at the Stanford Institute for Materials and Energy Sciences (SIMES) have improved an innovative solar-energy device to be about 100 times more efficient than its previous design in converting the sun’s light and heat into electricity.

‘This is a major step toward making practical devices based on our technique for harnessing both the light and heat energy provided by the sun,’ said Nicholas Melosh, associate professor of materials science and engineering at Stanford and a researcher with SIMES, a joint SLAC/Stanford institute.

Nick Melosh (left), associate professor of materials science and engineering at Stanford and a researcher with SIMES, and graduate student Jared Schwede. (Credit: Brad Plummer / SLAC)

The new device is based on the photon-enhanced thermionic emission (PETE) process first demonstrated in 2010 by a group led by Melosh and SIMES colleague Zhi-Xun Shen, who is SLAC’s advisor for science and technology. In a report last week in Nature Communications, the group described how they improved the device’s efficiency from a few hundredths of a percent to nearly 2 percent, and said they expect to achieve at least another 10-fold gain in the future.”

Part of a 2-inch-diameter gallium-arsenide wafer used as a base for photon-enhanced thermionic emission chips. (Credit: Brad Plummer / SLAC)

This is exciting news for Clean Energy. See the full article here.

SLAC 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 DOE’s Office of Science.

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From SLAC Lab: “Breakthrough Research Shows Chemical Reaction in Real Time”

March 14, 2013
No Writer Credit

“The ultrafast, ultrabright X-ray pulses of the Linac Coherent Light Source (LCLS) have enabled unprecedented views of a catalyst in action, an important step in the effort to develop cleaner and more efficient energy sources.

How LCLS views surface chemistry (Credit: Hirohito Ogasawara / SLAC National Accelerator Laboratory)

Scientists at the U.S. Department of Energy’s (DOE) SLAC National Accelerator Laboratory used LCLS, together with computerized simulations, to reveal surprising details of a short-lived early state in a chemical reaction occurring at the surface of a catalyst sample. The study offers important clues about how catalysts work and launches a new era in probing surface chemistry as it happens.

‘To study a reaction like this in real time is a chemist’s dream,’ said Anders Nilsson, deputy director for the Stanford and SLAC SUNCAT Center for Interface Science and Catalysis and a leading author in the research, published March 15 in Science. ‘We are really jumping into the unknown.’”

See the full article here.

SLAC 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 DOE’s Office of Science.

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From SLAC- “‘Beam Sharing’: Two Experiments with One X-ray Laser”

March 12, 2013
Glenn Roberts Jr.

“Blue-glowing diamond crystals hold promise for expanding the research capacity of SLAC’s X-ray laser by divvying up its pulses for use in separate, simultaneous experiments.

A superthin diamond glows blue during a beam-sharing experiment at SLAC’s Linac Coherent Light Source X-ray laser. (Credit: SLAC)

In a Feb. 6 test, scientists used perfect diamond crystals to separate ultrabright X-ray pulses at the Linac Coherent Light Source into groups of ‘colors,’ or wavelengths, for experiments spaced about 250 meters apart.

This much-anticipated feat – the result of years of work by SLAC scientists – was made possible by key contributions from researchers in three nations. The diamond crystals and their mounting hardware were crafted by the Technological Institute for Superhard and Novel Carbon Materials in Russia; taken to Argonne National Laboratory’s Advanced Photon Source for intensive characterization to determine their properties; and tested at SLAC. Scientists from the Max Planck Institute for Medical Research in Germany provided samples for one of the simultaneous experiments.

‘This is a long-awaited milestone, and all the scientists and institutes involved are to be congratulated on this achievement,’ said Jo Stöhr, LCLS director. ‘Last year, hard X-ray self-seeding provided our users with improved X-ray pulses, and now beam splitting will allow us to serve more users.’

Although the LCLS has six experimental stations, the fact that it has only one X-ray laser beam has limited it to running only one experiment at a time. Getting time for experiments at LCLS is highly competitive, and only about one in four research proposals can be accepted.

While more work is required before LCLS can routinely offer beam sharing to scientists who use the facility, the potential to increase the volume of experiments is exciting, said Diling Zhu, an LCLS instrument scientist who has been part of the effort.”

See the full article here.

SLAC 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 DOE’s Office of Science.

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From SLAC: “X-ray Laser Explores New Uses for DNA Building Blocks”

March 11, 2013
Glenn Roberts Jr.

The founding father of DNA nanotechnology – a field that forges tiny geometric building blocks from DNA strands – recently came to SLAC to get a new view of these creations using powerful X-ray laser pulses.

For decades, Nadrian C. “Ned” Seeman, a chemistry professor at New York University, has studied ways to assemble DNA strands into geometric shapes and 3-D crystals with applications in biology, biocomputing and nanorobotics.

Nadrian C. “Ned” Seeman, chemistry professor at New York University.

He said the experiment conducted Feb. 7-11 at SLAC’s Linac Coherent Light Source enabled his team for the first time to study the DNA structures using smaller crystals in solution at room temperature.

They want to find out whether they can analyze the structure of their samples more precisely in this natural state, as their previous work relied on larger, frozen samples and the freezing process can damage the DNA structures.

A six-sided structure formed by DNA strands. Researchers studied DNA structures such as this in an experiment at SLAC’s Linac Coherent Light Source. (Credit: Nadrian C. Seeman; Nature 461, 74-77, 2009)

‘I think we’ll get some pretty exciting results,’ Seeman said during the last shift of the team’s LCLS experiment. ‘I’m very excited by everything I have seen so far.’”

See the full article here.

SLAC 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 DOE’s Office of Science.

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From SLAC: “Unexpected Allies Help Bacteria Clean Uranium From Groundwater”

March 7, 2013
Lori Ann White

“Since 2009, SLAC scientist John Bargar has led a team using synchrotron-based X-ray techniques to study bacteria that help clean uranium from groundwater in a process called bioremediation. Their initial goal was to discover how the bacteria do it and determine the best way to help, but during the course of their research the team made an even more important discovery: Nature thinks bigger than that.

From left to right: Sam Webb, John Bargar and Juan Lezama-Pacheco used X-rays from the Stanford Synchrotron Radiation Lightsource to discover Nature’s housecleaning secrets. Since the housecleaning involves uranium, their curiosity may have important benefits. (Credit: Matt Beardsley)

The researchers discovered that bacteria don’t necessarily go straight for the uranium, as was often thought to be the case. The bacteria make their own, even tinier allies – nanoparticles of a common mineral called iron sulfide. Then, working together, the bacteria and the iron sulfide grab molecules of a highly soluble form of uranium known as U(VI), or hexavalent uranium, and transform them into U(IV), a less-soluble form that’s much less likely to spread through the water table. According to Barger, this newly discovered partnership may be the basis of a global geochemical process that forms deposits of uranium ore.

And it’s all done using one of the most basic types of chemical reactions known: oxidation and reduction, commonly known as ‘redox.’ Redox reactions can be thought of as the transfer of electrons from donor atoms to atoms that are hungry for electrons, and they are a primary source of chemical energy for both living and non-living processes. Photosynthesis involves redox reactions, as does cell respiration. Iron oxidizes to form rust; batteries depend on redox reactions to store and release energy.

‘Redox transitions are a very fundamental process,’ Bargar said. ‘It’s the stuff of life. It’s how you breathe.’”

The study, published Monday in the Proceeding of the National Academy of Sciences, was conducted at the Old Rifle site on the Colorado River, a former uranium ore processing site in the town of Rifle, Colo. The aquifer at the site is contaminated with uranium and is the focus of bioremediation field studies conducted by a larger team of scientists at Lawrence Berkeley National Laboratory and funded by the Department of Energy’s Office of Biological and Environmental Research. As part of their study, the LBNL team added acetate – essentially vinegar – to the aquifer in a series of injection wells to “feed the bugs,” as Bargar put it, allowing acetate to flow throughout the aquifer around the wells.

See the full article here.

SLAC 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 DOE’s Office of Science.

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From SLAC Lab: “An Impressive and Growing Array of Lasers at SLAC”

February 27, 2013
Glenn Roberts Jr.

“In less than a decade, SLAC has built up an impressive array of dozens of laser systems – and a team of laser scientists and engineers – with capabilities that make it one of the most cutting-edge national laboratories under the U.S. Department of Energy.

Joe Robinson, a staff scientist, at left, works with Mike Minitti, group leader for LCLS-related lasers, on a laser system to be used in an LCLS experiment. (Credit: Matt Beardsley)

Conventional optical lasers require three components: 1) a “pump source,” such as a flashlamp or other laser that provides an energy source; 2) a “lasing medium,” such as a specialized crystal that amplifies light; and 3) an “optical resonator,” which is a cavity with two end mirrors, one an end mirror that is highly reflective and the other an output mirror that partially transmits light, allowing light to circulate within the resonator. [Click thumbnail for full view.] (Laser components description courtesy of Mike Woods/SLAC. Laser diagram courtesy of Lakkasuo/Wikimedia Commons)

Lighting the way

SLAC’s newfound laser focus took shape with the 2005 hire of Bill White, a laser expert who had worked at Lawrence Livermore National Laboratory and in private enterprise. White was hired to help the lab prepare for the 2009 launch of the Linac Coherent Light Source, a unique X-ray laser with ultrabright, ultrashort pulses that requires more conventional lasers for most experiments.

The lab’s inventory of 135 high-power optical lasers includes 40 lasers that can be used in LCLS experiments. Another 18 lasers are installed at the LCLS injector, where they produce the beam of electrons that is converted into X-ray pulses.

There are 25 laser facilities at SLAC, and their laser systems serve in a variety of roles in experiments: aligning molecules in the same direction and orientation, shocking and compressing matter, switching magnetic states and exciting chemical reactions, as examples.

The lasers often incorporate off-the-shelf commercial components, though SLAC’s specialization in studying ultrafast processes, which can be measured in trillionths to quadrillionths of a second, requires customization, White said.

SLAC’s laser systems, at their core, represent ‘controlled energy that can interact with matter in countless ways,’ said Alan Fry, deputy director of SLAC’s Laser Science and Technology Division. “They allow us to stimulate very specific changes in materials and to probe and measure those changes with extreme precision.’”

See the full article here.

SLAC 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 DOE’s Office of Science.

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