From BNL: “A New X-Ray Microscope for Nanoscale Imaging”

Brookhaven Lab

February 26, 2015
Chelsea Whyte

Yong Chu and Evgeny Nazaretski work in front of the new microscope they designed and installed at the Hard X-ray Nanoprobe beamline at NSLS-II.

Delivering the capability to image nanostructures and chemical reactions down to nanometer resolution requires a new class of x-ray microscope that can perform precision microscopy experiments using ultra-bright x-rays from the National Synchrotron Light Source II (NSLS-II) at Brookhaven National Laboratory. This groundbreaking instrument, designed to deliver a suite of unprecedented x-ray imaging capabilities for the Hard X-ray Nanoprobe (HXN) beamline, brings researchers one step closer to the ultimate goal of nanometer resolution at NSLS-II, a U.S. Department of Energy Office of Science User Facility.

The microscope manipulates novel nanofocusing optics called multilayer Laue lenses (MLL) — incredibly precise lenses grown one atomic layer at a time — which produce a tiny x-ray beam that is currently about 10 nanometers in size. Focusing an x-ray beam to that level means being able to see the structures on that length scale, whether they are proteins in a biological sample, or the inner workings of a fuel cell catalyst.

The team of scientists who built this microscope aren’t stopping there; they are working toward making the focused x-ray beam spot even smaller in the future. The microscope they developed produces x-ray images by scanning a sample while collecting various x-ray signals emerging from the sample. Analysis of these signals helps researchers understand crucial information about the materials they are examining: density, elemental composition, chemical state, and the crystalline structure of the sample.

Fluorescence and phase-contrast images of a platinum test pattern completed in the new microscope at the Hard X-ray Nanoprobe beamline. No image credit.

Getting a clear image at this scale requires extremely high stability of the microscope to minimize vibrations and to reduce possible thermal drifts, changes in the microscope due to heat. It requires over twenty piezo motors — very fine motors that produce motion when electric currents are fed into piezo crystals — controlled down to nanometer-scale precision, crammed into a tight space about the size of a coffee maker, to meet its functionalities.

“This instrument incorporates most recent developments in interferometric sensing, nanoscale motion, and position control. Recorded drifts of two nanometers per hour are unprecedented and set a new benchmark for x-ray microscopy systems,” said Evgeny Nazaretski, a physicist at NSLS-II who spearheaded the development of the microscope.

Multi-layer Laue lens module inside the vacuum chamber of the microscope installed at the Hard X-ray Nanoprobe beamline at NSLS-II.

After construction, the MLL module, a key component of the HXN x-ray microscope, was tested at the Diamond Light Source Beamline I-13L for extensive x-ray performance measurements. These measurements confirmed the stability and reliability of the new MLL system. Results are being published in the March issue of the Journal of Synchrotron Radiation.

Hanfei Yan, a co-author of the paper, added, “We are grateful to our collaborators from Argonne National Laboratory who shared their technical expertise from the beginning of this project and also to collaborators from the Diamond Light Source who wholeheartedly supported the x-ray experiments.”

“This instrument is a critical link connecting NSLS-II’s bright x-rays to unprecedented nanoscale x-ray imaging capabilities, which we believe will lead to many groundbreaking scientific discoveries”, stressed Yong Chu, the Group Leader of the Hard X-ray Nanoprobe Beamline at NSLS-II. The HXN beamline and the HXN x-ray microscope are currently being commissioned and will be available for user experiments later this year.

This work is published in the Journal of Synchrotron Radiation.

See the full article here.

Please help promote STEM in your local schools.

Stem Education Coalition

One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world.Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.

From SLAC: “New Programs Enhance SIMES Role in Studying Exotic New Materials”

SLAC Lab

February 20, 2015

Projects to Support Research in ‘Valleytronics’

Two new three-year research projects are supporting the role of the Stanford Institute for Materials and Energy Sciences (SIMES) as a leading center for studying exotic new materials that could enable future innovative electronic and photonic applications. SIMES is a joint institute of Stanford University and the Department of Energy’s SLAC National Accelerator Laboratory.

“These awards are very important for SIMES,” said Tom Devereaux, a professor at SLAC and director of SIMES. “We have been establishing leadership in scientific areas that make SLAC unique. The awards significantly strengthen our core efforts in ultrafast science and quantum materials.”

The two complementary projects will explore several theoretical and experimental aspects of an emerging area called “valleytronics.” In valleytronics, electrons move through the lattice of a two-dimensional semiconductor as a wave with two energy valleys whose characteristics can be used to encode information.

Prime valleytronic materials are chalcogenides (pronounced cal-CAW-gin-eyeds), materials composed of a heavy metal atom and one or more atoms of oxygen, sulfur, selenium or tellurium. Many chalcogenides naturally form atom-scale layers that, under the right circumstances, result in special properties of interest to the SIMES researchers.

“For example,” said SIMES researcher Yi Cui, “shining certain types of light onto some chalcogenides can control their electrons’ movements in ways that produce properties favorable for their use in efficient photodetectors, low-energy computer logic and data storage chips or quantum computers.”

The SIMES researchers will perform theoretical calculations, make new nanomaterials and perform experiments in SLAC’s laboratories and DOE Office of Science User Facilities, including the Stanford Synchrotron Radiation Lightsource and the Linac Coherent Light Source. Their ultimate goal is to learn how to tune the materials to optimize their electronic properties.

“SIMES and SLAC provide a wonderful combination of expertise in material synthesis, advanced characterization capabilities and theory, bringing together the key ingredients to make progress in this exciting new field,” remarked Stanford/SLAC Professor and SLAC Chemical Sciences Division Director Tony Heinz.

One project, titled Induction and Dynamics of New States of Matter in Two-Dimensional Materials, is led by Devereaux, with co-investigators Zhi-Xun Shen, Aaron Lindenberg and Tony Heinz. It has received funding under the DOE’s “Scientific Discovery through Ultrafast Materials and Chemical Sciences” program. SLAC was the only DOE national lab chosen as a sole principal investigator in this program.

The second project, Chalcogenide Nanomaterials, is led by SIMES researcher Yi Cui with co-investigators Harold Hwang, Shoucheng Zhang, Jun-Sik Lee and Hongtao Yuan. After the project’s success with last year’s seed funding, the DOE has established a core program at SLAC in this novel area.

See the full article here.

Please help promote STEM in your local schools.

Stem Education Coalition

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.

From SLAC: “Scientists Get First Glimpse of a Chemical Bond Being Born”

SLAC Lab

February 12, 2015

Scientists have used an X-ray laser at the Department of Energy’s SLAC National Accelerator Laboratory to get the first glimpse of the transition state where two atoms begin to form a weak bond on the way to becoming a molecule.

This illustration shows atoms forming a tentative bond, a moment captured for the first time in experiments with an X-ray laser at SLAC National Accelerator Laboratory. The reactants are a carbon monoxide molecule, left, made of a carbon atom (black) and an oxygen atom (red), and a single atom of oxygen, just to the right of it. They are attached to the surface of a ruthenium catalyst, which holds them close to each other so they can react more easily. When hit with an optical laser pulse, the reactants vibrate and bump into each other, and the carbon atom forms a transitional bond with the lone oxygen, center. The resulting carbon dioxide molecule detaches and floats away, upper right. The Linac Coherent Light Source (LCLS) X-ray laser probed the reaction as it proceeded and allowed the movie to be created. (SLAC National Accelerator Laboratory)

This fundamental advance, reported Feb. 12 in Science Express and long thought impossible, will have a profound impact on the understanding of how chemical reactions take place and on efforts to design reactions that generate energy, create new products and fertilize crops more efficiently.

“This is the very core of all chemistry. It’s what we consider a Holy Grail, because it controls chemical reactivity,” said Anders Nilsson, a professor at the SLAC/Stanford SUNCAT Center for Interface Science and Catalysis and at Stockholm University who led the research. “But because so few molecules inhabit this transition state at any given moment, no one thought we’d ever be able to see it.”

Anders Nilsson, a professor at SLAC and at Stockholm University, explains how scientists used an X-ray laser to watch atoms form a tentative bond, and why that’s important.

The experiments took place at SLAC’s Linac Coherent Light Source (LCLS), a DOE Office of Science User Facility. Its brilliant, strobe-like X-ray laser pulses are short enough to illuminate atoms and molecules and fast enough to watch chemical reactions unfold in a way never possible before.

Researchers used LCLS to study the same reaction that neutralizes carbon monoxide (CO) from car exhaust in a catalytic converter. The reaction takes place on the surface of a catalyst, which grabs CO and oxygen atoms and holds them next to each other so they pair up more easily to form carbon dioxide.

In the SLAC experiments, researchers attached CO and oxygen atoms to the surface of a ruthenium catalyst and got reactions going with a pulse from an optical laser. The pulse heated the catalyst to 2,000 kelvins – more than 3,000 degrees Fahrenheit – and set the attached chemicals vibrating, greatly increasing the chance that they would knock into each other and connect.

The team was able to observe this process with X-ray laser pulses from LCLS, which detected changes in the arrangement of the atoms’ electrons – subtle signs of bond formation – that occurred in mere femtoseconds, or quadrillionths of a second.

“First the oxygen atoms get activated, and a little later the carbon monoxide gets activated,” Nilsson said. “They start to vibrate, move around a little bit. Then, after about a trillionth of a second, they start to collide and form these transition states.”

‘Rolling Marbles Uphill’

The researchers were surprised to see so many of the reactants enter the transition state – and equally surprised to discover that only a small fraction of them go on to form stable carbon dioxide. The rest break apart again.

“It’s as if you are rolling marbles up a hill, and most of the marbles that make it to the top roll back down again,” Nilsson said. “What we are seeing is that many attempts are made, but very few reactions continue to the final product. We have a lot to do to understand in detail what we have seen here.”

Theory played a key role in the experiments, allowing the team to predict what would happen and get a good idea of what to look for. “This is a super-interesting avenue for theoretical chemists. It’s going to open up a completely new field,” said report co-author Frank Abild-Pedersen of SLAC and SUNCAT.

A team led by Associate Professor Henrik Öström at Stockholm University did initial studies of how to trigger the reactions with the optical laser. Theoretical spectra were computed under the leadership of Stockholm Professor Lars G.M. Pettersson, a longtime collaborator with Nilsson.

Preliminary experiments at SLAC’s Stanford Synchrotron Radiation Lightsource (SSRL), another DOE Office of Science User Facility, also proved crucial. Led by SSRL’s Hirohito Ogasawara and SUNCAT’s Jerry LaRue, they measured the characteristics of the chemical reactants with an intense X-ray beam so researchers would be sure to identify everything correctly at the LCLS, where beam time is much more scarce. “Without SSRL this would not have worked,” Nilsson said.

The team is already starting to measure transition states in other catalytic reactions that generate chemicals important to industry.

“This is extremely important, as it provides insight into the scientific basis for rules that allow us to design new catalysts,” said SUNCAT Director and co-author Jens Nørskov.

Researchers from LCLS, Helmholtz-Zentrum Berlin for Materials and Energy, University of Hamburg, Center for Free Electron Laser Science, University of Potsdam, Fritz-Haber Institute of the Max Planck Society, DESY and University of Liverpool also contributed to the research. The research was funded by the DOE Office of Science, the Swedish National Research Council, the Knut and Alice Wallenberg Foundation, the Volkswagen Foundation and the German Research Foundation (DFG) Center for Ultrafast Imaging.

See the full article here.

Please help promote STEM in your local schools.

Stem Education Coalition

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.

From DESY: “Taking high-speed snapshots of living cells with an X-ray laser”

DESY

2015/02/11

X-ray imaging method captures living cells with unprecedented speed and resolution

An international team led by Uppsala University and including scientists from DESY and the European XFEL has for the first time successfully imaged whole living bacterial cells with an X-ray laser. The method used in this experiment can produce results that are of higher spatial and temporal resolution than even the best optical microscopy techniques, with the added possibility of creating detailed 3D models of the cells. “When you really want to understand the details of a cell’s functions, you need it alive”, says Uppsala University Professor Janos Hajdu, one of the lead researchers in the experiment and an advisor to European XFEL. The technique, as described in the journal Nature Communications, allows scientists a clearer view into the complicated world of the cell.

Reconstructed electron density of a cyanobacterium. Credit: Gjis van der Schot/Universität Uppsala

The method involves spraying the cells into a fine aerosol ahead of the pulses of an X-ray laser. This aerosol — literally a beam of living cells — has a thickness less than that of a human hair. The ultra-short X-ray pulses scatter from the individual cells and the resulting diffraction patterns are picked up by a detector. Computer programs, including several developed in collaboration between Uppsala and DESY, analyze the data and reconstruct the image of the cells.

“While the X-rays destroy the cells in the process, an X-ray laser’s ultra-short flashes and high intensity allow the diffraction data to be captured quickly enough to get an accurate picture of the sample before it disintegrates. The flashes outrun the damage,” says Anton Barty, a DESY scientist at the Center for Free Electron Laser Science who is also a co-author of this paper.

This technique, called “diffraction-before-destruction”, has been proven to work in several studies with biological and also with inorganic samples before. The cell imaging experiment took place at the LCLS X-ray laser at SLAC National Accelerator Laboratory in Menlo Park, California. Two types of cyanobacteria were used in the study called Cyanobium gracile and Synechococcus elongatus. These cells have a roughly cylindrical shape that is immediately apparent in the reconstructions from the diffraction data.

Nomarski image of the same cyanobacterium, calculated from the recontruction. Credit: Gjis van der Schot/Universität Uppsala

However, the leader of the experiment, Tomas Ekeberg, an assistant professor in molecular biophysics at Uppsala University, acknowledged that the pictures could have been even better but the data were more than the detectors could handle.

“We so far can only accurately reconstruct to 76 nanometres resolution, but the data we collected indicates that we can get down to 4 nanometres, which is the size of a protein molecule”, Ekeberg says. A nanometre is a billion times smaller than a metre. The reason for the drop in resolution was what amounted to an overexposure, just like too bright of a light in a photograph. “This experiment was a proof-of-concept study”, says Ekeberg. “We will be able to obtain much higher-resolution pictures when we can use a filter to help reduce the overexposure.” adds Gijs van der Schot, a Ph.D. student with Ekeberg and the first author on the paper.

Acquiring high-resolution micrographs from cells in conventional experiments has usually meant long exposure times and about a million times higher radiation doses than the dose that kills a living cell. As a consequence, much of what we know today about cells at high-resolution comes from dead material. The team’s new method can access the structure of living cells at practically instantaneous speeds, before radiation damage has time to set in. Each image is formed in femtoseconds. A femtosecond is a millionth of a billionth of a second. Such a revolutionary tool could help scientists better understand some of the mysteries of cellular function and behaviour. Additionally, this technique opens the door for future 3D modelling of cells and cellular activities, and provides key insights to fundamental processes in several important areas of disease research.

X-ray diffraction pattern produced by a cyanobacterium at the LCLS. Credit: Gjis van der Schot/Universität Uppsala

“This is a promising method for the European XFEL”, says Joachim Schulz, a scientist at European XFEL and one of the co-authors on the paper. “It could further expand the application of bio-imaging methods to users, opening possibilities to image living organisms.”

The team plans to fine-tune the imaging method with further experiments and work on consistently developing images at higher resolution. Additionally, Ekeberg and van der Schot predict that future studies would attempt to develop the 3D cell division models or target particular structural information about the cells for bioinformatics.

“The contrast is tremendous between images produced using this technique and those from traditional optical microscopy of living cells”, says Hajdu. “Few believed this was possible.”

The future for imaging is getting even brighter in Hamburg, as the European X-FEL will soon start generating ultra-short, ultra-intense X-ray pulses at 300 times higher repetition rate than the best X-ray lasers today.

See the full article here.

Please help promote STEM in your local schools.

Stem Education Coalition

DESY is one of the world’s leading accelerator centres. Researchers use the large-scale facilities at DESY to explore the microcosm in all its variety – from the interactions of tiny elementary particles and the behaviour of new types of nanomaterials to biomolecular processes that are essential to life. The accelerators and detectors that DESY develops and builds are unique research tools. The facilities generate the world’s most intense X-ray light, accelerate particles to record energies and open completely new windows onto the universe. 
That makes DESY not only a magnet for more than 3000 guest researchers from over 40 countries every year, but also a coveted partner for national and international cooperations. Committed young researchers find an exciting interdisciplinary setting at DESY. The research centre offers specialized training for a large number of professions. DESY cooperates with industry and business to promote new technologies that will benefit society and encourage innovations. This also benefits the metropolitan regions of the two DESY locations, Hamburg and Zeuthen near Berlin.

From FNAL: “Fermilab contributes to SLAC LCLS-II with cutting-edge technology and expertise”

Fermilab is an enduring source of strength for the US contribution to scientific research world wide.

Wednesday, Feb. 11, 2015
Rich Blaustein

Fermilab is developing superconducting accelerating cavities similar to this one for SLAC’s Linac Coherent Light Source II. Photo: Reidar Hahn

Now one year into its five-year construction plan, the Linac Coherent Light Source II, an electron accelerator project at SLAC, will produce a high-power free-electron laser for cutting-edge scientific explorations ranging from refined observations of molecules and cellular interactions to innovative materials engineering. Cornell University as well as Argonne National Laboratory, Lawrence Berkeley National Laboratory, Fermilab and Thomas Jefferson National Accelerator Facility are partners in the SLAC-directed project.

“We at the laboratories are all developing close ties,” said Richard Stanek, Fermilab LCLS-II team leader. “The DOE science lab complex will be stronger for this collaboration.”

In 2015, Fermilab will intensify its LCLS-II contribution in the overlapping areas of superconducting radio-frequency (SRF) accelerator technology and cryogenics, critical components that distinguish LCLS-II from SLAC’s current LCLS facility, whose laser production has enabled noted scientific investigations in cancer treatment and other important areas.

LCLS

LCLS-II

SLAC physicist Marc Ross, LCLS-II cryogenics systems manager, said LCLS cannot keep up with scientists’ requests for use. The existing LCLS facility and LCLS-II combined will offer researchers laser X-rays with a wide range of properties.

“This new approach will transform the repetition rate of LCLS — from 120 pulses per second to up to 1 million per second,” Ross said. “This will allow a completely new class of experiments and, eventually, a much larger number of experimental stations operated in parallel.”

Fermilab Technical Division physicists Hasan Padamsee, division head, and Anna Grassellino and their team are working on SRF technology for LCLS-II, in particular on implementing Fermilab’s two recent findings to reduce the needed cryogenic power. In one innovation, known as nitrogen doping, Grassellino found that infusing a small amount of nitrogen gas when preparing the superconducting cavities — the structures through which beam is accelerated — reduces two main causes of the usually expected resistance to radio-frequency currents.

“It is exciting to see our discovery becoming an enabling technology for LCLS-II,” Grassellino said.

Grassellino’s high-Q team has also found that the cavities’ cooling dynamics significantly helps expel magnetic flux, another major source of cavity power dissipation. The Fermilab high-Q team, together with Cornell University and Jefferson Lab, are currently working on calibrating the cooling thermogradient for LCLS-II.

Stanek said Fermilab is advancing its SRF work with its LCLS-II participation.

“I see this project taking us from an R&D phase of SRF technology, which is where we have been the past six to eight years, and moving our expertise into production,” Stanek said. “This is a big step forward.”

Fermilab and Jefferson Lab are working closely together on the cooling systems that enable the cavities’ superconductivity. Fermilab scientist Camille Ginsburg leads LCLS-II cryomodule production at Fermilab, and Fermilab engineer Arkadiy Klebaner manages the LCLS-II cryomodules distribution system.

“To build a high-energy beam using SRF technology, LCLS-II needed expertise in cryogenics,” Klebaner said. “So Jefferson Lab and Fermilab, who both have special expertise in this, were ready to help out.”

A cryogenic plant generating the refrigeration, a cryogenic distribution system for transporting the refrigeration into cryomodules and the cryomodules themselves make up the LCLS-II cryogenics. Jefferson Lab will provide the cryogenic plant, and Fermilab is in charge of developing the cryogenic distribution system. Jefferson Lab and Fermilab are jointly developing LCLS-II’s 35 cryomodules, each one about 10 meters long.

Fermilab’s contribution draws on the Tevatron’s cryogenics and on SRF research begun for the proposed International Linear Collider. The lab’s LCLS-II experience will also help with developing its planned PIP-II accelerator.

“So when we build the next accelerator for Fermilab, PIP-II, then we will have already gotten a lap around the production race course,” Padamsee said.

All labs have something special to contribute to LCLS-II, Ross said.

“The Fermilab team have figured out a way to make this kind of accelerator much better operating in the cold temperature that superconducting technology requires,” Ross said. “It is worthy of special recognition.”

See the full article here.

Please help promote STEM in your local schools.

Stem Education Coalition

Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics.

From NYT: “Unlocking Scrolls Preserved in Eruption of Vesuvius, Using X-Ray Beams”

The New York Times

JAN. 20, 2015
NICHOLAS WADE

Researchers have found a key that may unlock the only library of classical antiquity to survive along with its documents, raising at least a possibility of recovering vanished works of ancient Greek and Roman authors such as the lost books of Livy’s history of Rome.

The library is that of a villa in Herculaneum, a town that was destroyed in A.D. 79 by the eruption of Mount Vesuvius that obliterated nearby Pompeii. Though Pompeii was engulfed by lava, a mix of superhot gases and ash swept over Herculaneum, preserving the documents in a grand villa that probably belonged to the family of Lucius Calpurnius Piso Caesoninus, the father-in-law of Julius Caesar.

Though the hot gases did not burn the many papyrus rolls in the villa’s library, they turned them into cylinders of carbonized plant material. Many attempts have been made to unroll the carbonized scrolls since they were excavated in 1752.

Gases and ash from Mount Vesuvius turned the Herculaneum scrolls into carbonized plant material. Credit Salvatore Laporta/Associated Press

But all were highly destructive, and scholars eventually decided to leave the scrolls alone in the hope that better methods would be invented. More than 300 scrolls survive more or less intact, with many more fragments.

The archaeological excavations of Herculaneum in the villa dei Papiri, Italy. Credit Splash News, via Corbis

Researchers led by Vito Mocella, of the Institute for Microelectronics and Microsystems in Naples, Italy, now say that for the first time, they can read letters inside the scrolls without unrolling them. Using a laserlike beam of X-rays from the European Synchrotron in Grenoble, France, they were able to pick up the very slight contrast between the carbonized papyrus fibers and the ancient ink, soot-based and also made of carbon.

The contrast has allowed them to recognize individual Greek letters from the interior of the roll, Dr. Mocella’s team reported on Tuesday in the journal Nature Communications. “At least we know there are techniques able to read inside the papyri, finally,” Dr. Mocella said in an interview. His team is considering several ways to refine the power of their technique.

“If the technology is perfected, it will be a real leap forward,” said Richard Janko, a classical scholar at the University of Michigan who has translated some of the few scrolls that can be read.

The research team look upon the Herculaneum Scrolls during a sample installation. Credit J. Delattre

The Mocella team’s work is the second recent advance in reading the Herculaneum scrolls. In 2009, Brent Seales, a computer scientist at the University of Kentucky, succeeded in delineating the physical structure of a Herculaneum scroll by X-ray-computed tomography, a process similar to a CT scan. The layers of papyrus wound up inside the scroll are highly ruffled and irregular because the hot gases liberated all the water from the fibers as well as carbonizing them.

The Mocella team’s method visualizes letters free floating inside the scroll, but each letter will need to be assigned to its correct place on Dr. Seales’s surface before the letters can form words. Dr. Seales and Dr. Mocella worked with Herculaneum scrolls acquired by Napoleon in 1802 and belonging to the Institut de France in Paris.

“This is absolutely a major step forward,” Dr. Seales said of the Mocella report. “These guys are focused on showing the imagery with best contrast. But to really read the papyrus, you need to untangle its surface, which is the active area of my work.”

The Herculaneum Papyrus scroll. Credit D. Delattre/Bibliothèque de l’Institut de France

Classical scholars are particularly interested in the physicists’ progress because of the chance of uncovering lost works of Latin and Greek literature. Piso’s grand villa — which is the model for the Getty Villa, part of the J. Paul Getty Museum in Los Angeles — is thought to have probably contained a large and wide-ranging library, much of which may still exist in unexcavated portions of the building.

“It would have been odd for a villa of this sort not to have had a major library,” Dr. Janko said. “So this technology, when perfected, does open the way to rediscovering a lot more ancient literature.”

The scrolls that have been opened pertain mostly to Greek philosophy and contain several works by Epicurus and his adherent Philodemus. But the library may also have had a Latin section. This could contain some of the many lost works of Roman history and literature. Even the texts of known works would be of great interest.

“For a scholar, it would be wonderful to have a manuscript of Virgil written in his lifetime, because what we have are medieval manuscripts which have suffered many changes at the hands of copyists,” said David Sider, a professor of classics at New York University.

See the full article here.

Please help promote STEM in your local schools.

Stem Education Coalition

From SLAC: “First Direct Evidence that a Mysterious Phase of Matter Competes with High-Temperature Superconductivity”

SLAC Lab

December 19, 2014

SLAC Study Shows “Pseudogap” Phase Hoards Electrons that Might Otherwise Conduct Electricity with 100 Percent Efficiency

Scientists have found the first direct evidence that a mysterious phase of matter known as the “pseudogap” competes with high-temperature superconductivity, robbing it of electrons that otherwise might pair up to carry current through a material with 100 percent efficiency.

The result, led by researchers at Stanford University and the Department of Energy’s SLAC National Accelerator Laboratory, is the culmination of 20 years of research aimed at finding out whether the pseudogap helps or hinders superconductivity, which could transform society by making electrical transmission, computing and other areas much more energy efficient.

This illustration shows the complex relationship between high-temperature superconductivity (SC) and a mysterious phase called the pseudogap (PG). Copper oxide materials become superconducting when an optimal number of electrons are removed, leaving positively charged “holes,” and the material is chilled below a transition temperature (blue curve). This causes remaining electrons (yellow) to pair up and conduct electricity with 100 percent efficiency. Experiments at SLAC have produced the first direct evidence that the pseudogap competes for electrons with superconductivity over a wide range of temperatures at lower hole concentrations (SC+PG). At lower temperatures and higher hole concentrations, superconductivity wins out. (SLAC National Accelerator Laboratory)

The new study definitively shows that the pseudogap is one of the things that stands in the way of getting superconductors to work at higher temperatures for everyday uses, said lead author Makoto Hashimoto, a staff scientist at SLAC’s Stanford Synchrotron Radiation Lightsource (SSRL), the DOE Office of Science User Facility where the experiments were carried out. The results were published in Nature Materials.

SSRL

“Now we have clear, smoking-gun evidence that the pseudogap phase competes with and suppresses superconductivity,” Hashimoto said. “If we can somehow remove this competition, or handle it better, we may be able to raise the operating temperatures of these superconductors.”

Tracking Down Electrons

In the experiments, researchers used a technique called angle-resolved photoemission spectroscopy, or ARPES, to knock electrons out of a copper oxide material, one of a handful of materials that superconduct at relatively high temperatures – although they still have to be chilled to at least minus 135 degrees Celsius.

Plotting the energies and momenta of the ejected electrons tells researchers how they were behaving when they were inside the material. In metals, for instance, electrons freely flow around and between atoms. In insulators, they stick close to their home atoms. And in superconductors, electrons leave their usual positions and pair up to conduct electricity with zero resistance and 100 percent efficiency; the missing electrons leave a characteristic gap in the researchers’ plots.

But in the mid-1990s, scientists discovered another, puzzling gap in their plots of copper oxide superconductors. This “pseudogap” looked like the one left by superconducting electrons, but it showed up at temperatures too warm for superconductivity to occur. Was it a lead-in to superconducting behavior? A rival state that held superconductivity at bay? Where did it come from? No one knew.

“It’s a complex, intimate relationship. These two phenomena likely share the same roots but are ultimately antagonistic,” said Zhi-Xun Shen, a professor at SLAC and Stanford and senior author of the study. “When the pseudogap is winning, superconductivity is losing ground.”

Evidence of Competition

Shen and his colleagues have been using ARPES to investigate the pseudogap ever since it showed up, refining their techniques over the years to pry more information out of the flying electrons.

In this latest study, Hashimoto was able to find out exactly what was happening at the moment the material transitioned into a superconducting state. He did this by measuring not only the energies and momenta of the electrons, but the number of electrons coming out of the material with particular energies over a wide range of temperatures, and after the electronic properties of the material had been altered in various ways.

He discovered clear, strong evidence that at this crucial transition temperature, the pseudogap and superconductivity are competing for electrons. Theoretical calculations by members of the team were able to reproduce this complex relationship.

“The pseudogap tends to eat away the electrons that want to go into the superconducting state,” explained Thomas Devereaux, a professor at Stanford and SLAC and co-author of the study. “The electrons are busy doing the dance of the pseudogap, and superconductivity is trying to cut in, but the electrons are not letting that happen. Then, as the material goes into the superconducting state, the pseudogap gives up and spits the electrons back out. That’s really the strongest evidence we have that this competition is occurring.”

Remaining Mysteries

Scientists still don’t know what causes the pseudogap, Devereaux said: “This remains one of the most important questions in the field, because it’s clearly preventing superconductors from working at even higher temperatures, and we don’t know why.”

But the results pave new directions for further research, the scientists said.

“Now we can model the competition between the pseudogap and superconductivity from the theoretical side, which was not possible before,” Hashimoto said. “We can use simulations to reproduce the kinds of features we have seen, and change the variables within those simulations to try to pin down what the pseudogap is.”

He added, “Competition may be only one aspect of the relationship between the two states. There may be more profound questions – for example, whether the pseudogap is necessary for superconductivity to occur.”

In addition to SLAC and Stanford, researchers from Lawrence Berkeley National Laboratory, Osaka University, the National Institute of Advanced Industrial Science and Technology in Japan, the Japan Atomic Energy Agency, Tokyo Institute of Technology, University of Tokyo and Cornell University contributed to the study. The research was supported by the DOE Office of Science.

See the full article here.

Please help promote STEM in your local schools.

Stem Education Coalition

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.

From LBL: “News Center Back to the Future with Roman Architectural Concrete”

Berkeley Lab

December 15, 2014
Lynn Yarris (510) 486-5375

No visit to Rome is complete without a visit to the Pantheon, Trajan’s Markets, the Colosseum, or the other spectacular examples of ancient Roman concrete monuments that have stood the test of time and the elements for nearly two thousand years. A key discovery to understanding the longevity and endurance of Roman architectural concrete has been made by an international and interdisciplinary collaboration of researchers using beams of X-rays at the Advanced Light Source (ALS) of the U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab).

ALS at LBL

The concrete walls of Trajan’s Markets in Rome have stood the test of time and the elements for nearly 2,000 years. They have even survived a major earthquake in 1349. (Photo courtesy of Marie Jackson)

Working at ALS beamline 12.3.2, a superconducting bending magnet X-ray micro-diffraction beamline, the research team studied a reproduction of Roman volcanic ash-lime mortar that had been previously subjected to fracture testing experiments at Cornell University. In the concrete walls of Trajan’s Markets, constructed around 110 CE, this mortar binds cobble-sized fragments of tuff and brick. Through observing the mineralogical changes that took place in the curing of the mortar over a period of 180 days and comparing the results to 1,900 year old samples of the original, the team discovered that a crystalline binding hydrate prevents microcracks from propagating.

“The mortar resists microcracking through in situ crystallization of platy strätlingite, a durable calcium-alumino-silicate mineral that reinforces interfacial zones and the cementitious matrix,” says Marie Jackson, a faculty scientist with the University of California (UC) Berkeley’s Department of Civil and Environmental Engineering who led this study. “The dense intergrowths of the platy crystals obstruct crack propagation and preserve cohesion at the micron scale, which in turn enables the concrete to maintain its chemical resilience and structural integrity in a seismically active environment at the millennial scale.”

(From left) Marie Jackson, Qinfei Li, Martin Kunz and Paulo Monteiro at ALS Beamline 12.3.2 where they conducted a study on ancient Roman concrete. (Photo by Roy Kaltschmidt)

Jackson, a volcanologist by training who led an earlier study at the ALS on Roman seawater concrete, is the lead author of a paper describing this study in the Proceedings of the National Academy of Sciences (PNAS) titled Mechanical Resilience and Cementitious Processes in Imperial Roman Architectural Mortar. Co-authors of the paper are Eric Landis, Philip Brune, Massimo Vitti, Heng Chen, Qinfei Li, Martin Kunz, Hans-Rudolf Wenk, Paulo Monteiro and Anthony Ingraffea.

The mortars that bind the concrete composites used to construct the structures of Imperial Rome are of keen scientific interest not just because of their unmatched resilience and durability, but also for the environmental advantages they offer. Most modern concretes are bound by limestone-based Portland cement. Manufacturing Portland cement requires heating a mix of limestone and clay to 1,450 degrees Celsius (2,642 degrees Fahrenheit), a process that releases enough carbon – given the 19 billion tons of Portland cement used annually – to account for about seven-percent of the total amount of carbon emitted into the atmosphere each year.

Roman architectural mortar, by contrast, is a mixture of about 85-percent (by volume) volcanic ash, fresh water, and lime, which is calcined at much lower temperature than Portland cement. Coarse chunks of volcanic tuff and brick compose about 45-to-55-percent (by volume) of the concrete. The result is a significant reduction in carbon emissions.

“If we can find ways to incorporate a substantial volumetric component of volcanic rock in the production of specialty concretes, we could greatly reduce the carbon emissions associated with their production also improve their durability and mechanical resistance over time,” Jackson says.

Ancient Roman concrete consists of coarse chunks of volcanic tuff and brick bound together by a volcanic ash-lime mortar that resists microcracking, a key to its longevity and endurance. (Photo by Roy Kaltschmidt, Berkeley Lab)

As part of their study, Jackson and her collaborators at UC Berkeley used ALS beamline 12.3.2 to make X-ray micro-diffraction measurements of slices of the Roman mortar that were only about 0.3 millimeters thick.

“We obtained X-ray diffractograms for many different points within a given cementitious microstructure,” Jackson says. “This enabled us to detect changes in mineral assemblages that gave precise indications of chemical processes active over very small areas.”

The mineralogical changes that Jackson and her collaborators observed showed the mortar reproduction gaining strength and toughness over 180 days as calcium-aluminum-silicate-hydrate (C-A-S-H) cementing binder coalesced and strätlingite crystals grew in interfacial zones between volcanic scoria and the mortar matrix. The toughening of these interfacial zones is reflected in the bridging crack morphology, which was measured by co-author Landis at the University of Maine, using computed tomography scans of the fractured mortar specimens. These experimental results correlate well with computations of increasing fracture energy determined by co-author Brune, now at Dupont Technologies. The strätlingite crystals show no corrosion and their smooth surfaces suggest long-term stability, similar to geological strätlingite that persists for hundreds of thousands of years.

“The in situ crystallization of the strätlingite crystals produces interfacial zones that are very different from any interfacial microstructure observed in Portland cement concretes,” Jackson says. “High porosity along the interfacial zones of inert aggregates in Portland cement concrete creates the sites where crack paths first nucleate and propagate.”

A future challenge for researchers, Jackson says, will be to “find ways to activate aggregates, as slag or as volcanic ash for example, in innovative concretes so that these can develop strätlingite reinforcements in interfacial zones like the Roman architectural mortars.”

The fracture testing experiments at Cornell University were led by co-author Ingraffea. The samples of mortar from Trajan’s Markets were provided by co-author Vitti and the Sovrintendenza Capitolina di Roma Capitale. Co-author Kunz is the principal scientist at ALS beamline 12.3.2.

This research was supported by the National Science Foundation and the Loeb Library at Harvard University. The Advanced Light Source is a DOE Office of Science User Facility.

See the full article here.

Please help promote STEM in your local schools.

Stem Education Coalition

A U.S. Department of Energy National Laboratory Operated by the University of California

From BNL: “Unusual Electronic State Found in New Class of Unconventional Superconductors”

Brookhaven Lab

December 8, 2014
Karen McNulty Walsh, (631) 344-8350 or Peter Genzer, (631) 344-3174

Finding gives scientists a new group of materials to explore to unlock secrets of some materials’ ability to carry current with no energy loss

A team of scientists from the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory, Columbia Engineering, Columbia Physics and Kyoto University has discovered an unusual form of electronic order in a new family of unconventional superconductors. The finding, described in the journal Nature Communications, establishes an unexpected connection between this new group of titanium-oxypnictide superconductors and the more familiar cuprates and iron-pnictides, providing scientists with a whole new family of materials from which they can gain deeper insights into the mysteries of high-temperature superconductivity.

Team members conducting research at Brookhaven Lab, led by Simon Billinge of Brookhaven and Columbia Engineering (seated), included (l to r) Columbia U graduate student Ben Frandsen and Weiguo Yin, Yimei Zhu, and Emil Bozin of Brookhaven’s Condensed Matter Physics and Materials Science Department. They used the aberation-corrected electron microscope in Zhu’s lab to conduct electron diffraction experiments that were a key component of this study. Collaborators not shown: Hefei Hu, formerly of Brookhaven Lab and now at Intel, Yasumasa Nozaki and Hiroshi Kageyama of Kyoto University, and Yasutomo Uemura of Columbia.

“Finding this new material is a bit like an archeologist finding a new Egyptian pharaoh’s tomb,” said Simon Billinge, a physicist at Brookhaven Lab and Columbia University’s School of Engineering and Applied Science, who led the research team. “As we try and solve the mysteries behind unconventional superconductivity, we need to discover different but related systems to give us a more complete picture of what is going on—just as a new tomb will turn up treasures not found before, giving a more complete picture of ancient Egyptian society.”

Harnessing the power of superconductivity, or the ability of certain materials to conduct electricity with zero energy loss, is one of the most exciting possibilities for creating a more energy-efficient future. But because most superconductors only work at very low temperatures—just a few degrees above absolute zero, or -273 degrees Celsius—they are not yet useful for everyday life. The discovery in the 1980s of “high-temperature” superconductors that work at warmer temperatures (though still not room temperature) was a giant step forward, offering scientists the hope that a complete understanding of what enables these materials to carry loss-free current would help them design new materials for everyday applications. Each new discovery of a common theme among these materials is helping scientists unlock pieces of the puzzle.

One of the greatest mysteries is seeking to understand how the electrons in high-temperature superconductors interact, sometimes trying to avoid each other and at other times pairing up—the crucial characteristic enabling them to carry current with no resistance. Scientists studying these materials at Brookhaven and elsewhere have discovered special types of electronic states, such as “charge density waves,” where charges huddle to form stripes, and checkerboard patterns of charge. Both of these break the “translational symmetry” of the material—the repetition of sameness as you move across the surface (e.g., moving across a checkerboard you move from white squares to black squares).

Another pattern scientists have observed in the two most famous classes of high-temperature superconductors is broken rotational symmetry without a change in translational symmetry. In this case, called nematic order, every space on the checkerboard is white, but the shapes of the spaces are distorted from a square to a rectangle; as you turn round and round on one space, your neighboring space is nearer or farther depending on the direction you are facing. Having observed this unexpected state in the cuprates and iron-pnictides, scientists were eager to see whether this unusual electronic order would also be observed in a new class of titanium-oxypnictide high-temperature superconductors discovered in 2013.

“These titanium-oxypnictide compounds are structurally similar to the other exotic superconductor systems, and they had all the telltale signs of a broken symmetry, such as anomalies in resistivity and thermodynamic measurements. But there was no sign of any kind of charge density wave in any previous measurement. It was a mystery,” said Emil Bozin, whose group at Brookhaven specializes in searching for hidden local broken symmetries. “It was a natural for us to jump on this problem.”

Top: Ripples extending down the chain of atoms breaks translational symmetry (like a checkerboard with black and white squares), which would cause extra spots in the diffraction pattern (shown as red dots in the underlying diffraction pattern). Bottom: Stretching along one direction breaks rotational symmetry but not translational symmetry (like a checkerboard with identical squares but stretched in one of the directions), causing no additional diffraction spots. The experiments proved these new superconductors have the second type of electron density distribution, called a nematic. Image credit: Ben Frandsen

The team searched for the broken rotational symmetry effect, a research question that had been raised by Tomo Uemura of Columbia, using samples provided by his collaborators in the group of Hiroshi Kageyama at Kyoto University. They conducted two kinds of diffraction studies: neutron scattering experiments at the Los Alamos Neutron Science Center (LANSCE) at DOE’s Los Alamos National Laboratory, and electron diffraction experiments using a transmission electron microscope at Brookhaven Lab.

“We used these techniques to observe the pattern formed by beams of particles shot through powder samples of the superconductors under a range of temperatures and other conditions to see if there’s a structural change that corresponds to the formation of this special type of nematic state,” said Ben Frandsen, a graduate student in physics at Columbia and first author on the paper.

The experiments revealed a telltale symmetry breaking distortion at low temperature. A collaborative effort among experimentalists and theorists established the particular nematic nature of the order.

“Critical in this study was the fact that we could rapidly bring to bear multiple complementary experimental methods, together with crucial theoretical insights—something made easy by having most of the expertise in residence at Brookhaven Lab and wonderfully strong collaborations with colleagues at Columbia and beyond,” Billinge said.

The discovery of nematicity in titanium-oxypnictides, together with the fact that their structural and chemical properties bridge those of the cuprate and iron-pnictide high-temperature superconductors, render these materials an important new system to help understand the role of electronic symmetry breaking in superconductivity.

As Billinge noted, “This new pharaoh’s tomb indeed contained a treasure: nematicity.”

This work was supported by the DOE Office of Science, the U.S. National Science Foundation (NSF, OISE-0968226), the Japan Society of the Promotion of Science, the Japan Atomic Energy Agency, and the Friends of Todai Inc.

See the full article here.

Please help promote STEM in your local schools.

Stem Education Coalition

One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world.Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.

From SLAC: “Rattled Atoms Mimic High-temperature Superconductivity”

SLAC Lab

December 4, 2014

X-ray Laser Experiment Provides First Look at Changes in Atomic Structure that Support Superconductivity

An experiment at the Department of Energy’s SLAC National Accelerator Laboratory provided the first fleeting glimpse of the atomic structure of a material as it entered a state resembling room-temperature superconductivity – a long-sought phenomenon in which materials might conduct electricity with 100 percent efficiency under everyday conditions.

In a high-temperature superconducting material known as YBCO, light from a laser causes oxygen atoms (red) to vibrate between layers of copper oxide that are just two molecules thick. (The copper atoms are shown in blue.) This jars atoms in those layers out of their normal positions in a way that likely favors superconductivity. In this short-lived state, the distance between copper oxide planes within a layer increases, while the distance between the layers decreases. (Jörg Harms/Max Planck Institute for the Structure and Dynamics of Matter)

Researchers used a specific wavelength of laser light to rattle the atomic structure of a material called yttrium barium copper oxide, or YBCO. Then they probed the resulting changes in the structure with an X-ray laser beam from the Linac Coherent Light Source (LCLS), a DOE Office of Science User Facility.

LCLS at SLAC

They discovered that the initial exposure to laser light triggered specific shifts in copper and oxygen atoms that squeezed and stretched the distances between them, creating a temporary alignment that exhibited signs of superconductivity for a few trillionths of a second at well above room temperature – up to 60 degrees Celsius (140 degrees Fahrenheit). The scientists coupled data from the experiment with theory to show how these changes in atomic positions allow a transfer of electrons that drives the superconductivity.

New Views of Atoms in Motion

“This is a highly interesting state, even though it only exists for a short period of time,” said Roman Mankowsky of the Max Planck Institute for the Structure and Dynamics of Matter in Hamburg, Germany, who was lead author of a report on the experiment in the Dec. 4 print issue of Nature. “When the laser excites the material, it shifts the atoms and changes the structure. We hope these results will ultimately help in the design of new materials to enhance superconductivity.”

Sustaining such a state at room temperature would revolutionize many fields, making the electrical grid more efficient and enabling more powerful and compact computers. Traditional superconductors operate only at temperatures close to absolute zero. YBCO is one of a handful of materials discovered since 1986 that superconduct at somewhat higher temperatures; but they still have to be chilled to at least minus 135 degrees Celsius in order to sustain superconductivity, and scientists still don’t know what allows these so-called high-temperature superconductors to carry electricity with zero resistance.

A Powerful Tool for Exploring Superconductivity

Josh Turner, a SLAC staff scientist who has led other studies of YBCO at the LCLS, said powerful tools such as X-ray lasers have excited new interest in superconductor research by allowing researchers to isolate a specific property that they want to learn more about. This is important because high-temperature superconductors can exhibit a tangle of magnetic, electronic and structural properties that may compete or cooperate as the material moves toward a superconducting state. For example, another recently published LCLS study found that exciting YBCO with the same optical laser light disrupts an electronic order that competes with superconductivity.

“What LCLS is now showing us is how these different properties change over short times,” Turner said. “We can actually see how the electrons or atoms are moving.”

Mankowsky said future experiments at LCLS could try to sustain the superconducting state for longer periods, use a combination of experimental techniques to study how other properties evolve in the transition into the superconducting state and explore whether the same structural changes are at work in other high-temperature superconductors.

Researchers from the National Center for Scientific Research in France, Paul Scherrer Institute in Switzerland, Max Planck Institute for Solid State Research in Germany, Swiss Federal Institute of Technology, College of France, University of Geneva, Oxford University in the United Kingdom, the Center for Free-Electron Laser Science in Germany, and University of Hamburg in Germany also participated in the study. The work was supported by the European Research Council, German Science Foundation, Swiss National Superconducting Center and Swiss National Science Foundation.

See the full article here.

Please help promote STEM in your local schools.

Stem Education Coalition

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.