These are a few of the Laboratory's achievements during 2013 in ST&E.
In a paper published in Physical Review Letters, Livermore scientist Felicie Albert and colleagues at LLNL, UCLA, and the Stanford Linear Accelerator Center present the first-ever measurements of the angular dependence of the betatron x-ray spectrum generated using a laser-wakefield accelerator (LWFA). The team performed experiments at LLNL’s Jupiter Laser Facility, using the 200-terawatt Callisto laser system, and then used simultaneous spectral and spatial analysis of the resulting x-rays to reconstruct the electron trajectories within the laser wake field with micrometer resolution, finding an angular dependence that strongly indicates anisotropy (i.e., direction dependence) in these electron trajectories.
This finding has significant implications in fusion energy research and other areas of high-energy-density research that use an LWFA to generate matter-probing x-rays as a laser-driven alternative to very large and very expensive free-electron particle accelerators. This work by Felicie et al. was supported by the LDRD Program. The photo shows Felicie (center) and Bradley Pollock (far right). Read More »
U.S. Energy Secretary Moniz announced the final shipment of low-enriched uranium (LEU) derived from Russian weapons-origin highly enriched uranium (HEU) under the 1993 U.S.–Russia HEU Purchase Agreement. Designed to prevent weapons-grade uranium from dismantled Russian nuclear weapons from falling into the hands of terrorists or rogue states, the agreement was a key implementation of the Treaty on the Nonproliferation of Nuclear Weapons. Under the agreement, Russia down-blended 500 metric tons of HEU, equivalent to 20,000 nuclear warheads, into LEU, thus achieving the agreement’s original target for the 20-year period.
The resulting LEU has been delivered to the United States, fabricated into nuclear fuel, and used in nuclear power plants to generate nearly ten percent of all U.S. electricity over the past 15 years. Lawrence Livermore, as lead laboratory for the program, supplied personnel for the monitoring trips, provided all of the health physics support, maintaining a repository of the collected monitoring data, and developed and deployed radiation detection equipment, such as a portable nondestructive assay system used to verify the contents of uranium containers (photo) without breaking their seals. (Image courtesy of USEC.) Read More »
Livermore researchers have received five awards in the latest R&D 100 Awards competition, which selects the world's top 100 innovations with commercial potential. U.S. Secretary of Energy Ernest Moniz praised the winners, stating, "The scientists and engineers who developed these award-winning technologies at the cutting-edge facilities across our national labs are keeping Americans at the forefront of the innovation community and assuring our nation's economic competitiveness and national security."
The image is a simplified schematic of the award-winning Movie Mode Dynamic Transmission Electron Microscope, which can capture billionth-of-a-meter-scale images at frame rates more than 100,000 times faster than those of conventional technique. Livermore's other winning technologies are Mantevo Suite 1.0, the first integrated suite of "miniapps" for supercomputer applications; Laser Screening at High-throughput to Identify Energetic Laser Distortion, which reduces the time to screen the National Ignition Facility's (NIF's) 48 laser checkpoints from 12 hours to less than 1 second—critical to NIF's success as an innovation-enabling user facility; DNA-Tagged Reagents for Aerosol Experiments, a safe, versatile surrogate for dangerous substances for use in threat assessments of ventillation and other building airflow systems; and Efficient Mode Converters for High-Power Fiber Amplifiers, which overcomes a key limitation of high-power fiber lasers by using a rectangular core that maintains beam quality as power is increased. This year's results bring to 148 the number of R&D 100 Awards the Laboratory has captured since 1978. Read More »
An LLNL team, in collaboration with Rensselaer Polytechnic Institute, successfully demonstrated a strong scaling study for parallel discrete event simulation on Sequoia, sustaining an aggregate speed of 504 billion events per second, dramatically exceeding the previous world record for discrete event simulation of 12 billion events per second. The simulation—which used a simulation package developed at Rensselaer and the Time Warp synchronization algorithm, originally developed at LLNL—demonstrates that direct simulation of planetary-scale models is now within reach. (Time Warp's capabilities were also announced in an invited paper at this year's Principles of Advanced Discrete Simulation Conference.) This includes simulations large enough to represent all 7 billion people in the world or the entire Internet's few billion hosts. Read More »
In addition, a simulation on Sequoia running the OSIRIS particle-in-cell (PIC) code used all 1,572,864 cores of Sequoia, thus becoming the largest PIC simulation by number of cores ever performed. The simulation studied the interaction—shown in the figure—of ultrapowerful lasers with dense plasmas in a proposed method to produce fusion energy. The simulations were conducted by Livermore's Frederico Fuiza, a Lawrence fellow whose award-winning doctoral dissertation was based on this and other research. Sequoia makes it possible for researchers like Frederico to computationally study the simultaneous evolution of tens of billions to trillions of individual particles in such highly complex systems. Read More »
LLNL physicist Yuan Ping was chosen for a DOE Office of Science Early Career Research Program (ECRP) Award. The award provides $2.5 million over 5 years to support the research of outstanding scientists early in their careers and to stimulate research careers in disciplines supported by the Office of Science. "I am very honored and grateful for this great opportunity to do more high-quality work," Yuan said. Her project, selected by the Office of Fusion Research, aims to provide high-quality data on critical energy transport properties of high-energy-density (HED) matter. Transport processes such as thermal and electrical conduction, radiation, viscosity, electron equilibration, and particle stopping determine the mechanisms and rates of energy transfer and redistribution within HED matter. "These energy partition pathways must be properly diagnosed and understood in order to develop and benchmark next-generation advanced models for extreme HED conditions such as those found in inertial confinement fusion," she explained. The data also will impact many other fields where HED science plays a crucial role, such as studies of geophysical phenomena, planetary formation, and astrophysical objects. This year, 61 ECRP awardees were selected from a pool of about 770 applicants from universities and national labs. Yuan is the 10th Livermore recipient since the program's inception in 2010. Read More »
Livermore researcher Nir Goldman and former LLNL postdoc Isaac Tamblyn (now at the University of Ontario Institute of Technology) have published a paper in The Journal of Physical Chemistry A on prebiotic chemistry occurring in comets impacting an ancient Earth. Their research—featured on the journal's cover—concludes that the combination of chemicals (such as ammonia and methanol) in cometary ice and the energy generated by impact could have synthesized important precursors of life without the need for other special conditions, such as chemical catalysts or ultraviolet radiation. Read More »
Late last year, an LLNL team led by Andrea Schmidt published in Physical Review Letters a breakthrough in plasma research — the first-ever fully kinetic model of a dense plasma focus that can track physical quantities at the particle level and thereby predict neutron yields more accurately. Now, this research has attracted support from the Defense Advanced Research Projects Agency (DARPA), which has allocated $1 million for research at Livermore. DARPA seeks to use Z-pinches to make compact neutron sources for applications that require more neutrons than are possible with today's state-of-the art dense plasma focus experiments. In our rendering of a Z-pinch, an umbrella-shaped plasma sheath (purple) is pushed down a cylindrical electrode, then collapses in on itself to create a dense region (white) that "pinches" and thereby accelerates an ion beam (green). Read More »
In conjunction with Women’s History Month in March, DOE launched a new website—called “WOMEN @ ENERGY”—to feature women researchers and their work in the DOE complex, with the goal of demonstrating to young women who are considering a career in science, technology, engineering, or mathematics (STEM) the breadth of opportunities that are available to them in STEM fields at DOE’s national laboratories and other sites. Among the LLNL researchers profiled on the website so far are Debra Callahan, Trish Damkroger, Maya Gokhale, Robin Goldstone, Kelley Herndon-Ford, Hye-Sook Park, Dawn Shaughnessy, Rea Simpson, and Eileen Vergino. Read More »
In a paper published in the Proceedings of the National Academy of Sciences, LLNL researchers Peter Weber, Ian Hutcheon, and Kevin Carpenter, with colleagues from the University of Illinois and the National Institutes of Health, report on a new method for mapping the distribution of small molecules in a cell membrane. Previous research suggested that lipids in the membrane assemble into patches that differ in composition and help cell membrane proteins carry out basic functions, but understanding had been hampered by the inability to directly image their spatial distribution. Using LLNL's nanoscale secondary ion mass spectrometry (nanoSIMS), Peter et al. made high-spatial-resolution images of the distribution of nitrogen-15-labelled sphingolipids, which had been thought to associate with cholesterol to form small domains about 200 nanometers across.
The nanoSIMS images revealed that sphingolipids form domains much larger than previously thought, that the 200-nanometer domains cluster together to form micrometer-sized patches, and that domain formation was affected less by cholesterol than by proteins underlying the membrane. These findings fundamentally challenge existing assumptions about how lipids and proteins are organized in the cell membrane, and that data collected with imaging techniques targeting the underlying proteins are not as accurate in representing sphingolipid distribution as previously thought. LLNL's work in this project was funded by the Laboratory Directed Research and Development (LDRD) Program. The image combines nanoSIMS data with secondary electron images to visually show local elevations in sphingolipid abundance (red and yellow). Read More »
Topics ranging from the behavior of hydrogen and helium at extreme densities to "surprises" in planetary physics research were explored at a workshop at LLNL last December on using the capabilities of the National Ignition Facility (NIF) to study the interiors of giant planets. Hosted by LLNL's Rip Collins and UC Berkeley's Raymond Jeanloz, the workshop discussed how the unprecedented temperatures and pressures created by NIF can further researchers' understanding of the physics involved in the creation and evolution of planets. Also discussed was the science of materials subjected to pressures higher than one terapascal (ten million times Earth's atmospheric pressure). Outside organizations represented at the workshop include the California Institute of Technology, the Carnegie Institution of Washington, the Institute of Shock Physics at Washington State University, and the Centre for Science at Extreme Conditions at the University of Edinburgh. Read More »
A Nature paper authored by an international team including LLNL astrophysicist and LDRD Program Director Bill Craig reports the first-ever definitive measurement of the spin rate of a supermassive black hole. The findings—made by the two x-ray space observatories, NASA's Nuclear Spectroscopic Telescope Array (NuSTAR) and the European Space Agency's XMM-Newton—solve a longstanding debate about similar measurements in other black holes. This knowledge about spin is important because, as the Nature "News and Views" highlight about the article explains, "our understanding of galaxy formation and evolution is intimately linked to our understanding of supermassive black holes."
The energy released by a growing supermassive black hole can be so powerful that it disrupts the normal growth of the host galaxy. Says Bill, "We know that black holes have a strong link to their host galaxy. Measuring the spin, one of the few things we can directly measure from a black hole, will give us clues to understanding this fundamental relationship." Important optics design and testing work for NuSTAR was done at LLNL, where this x-ray-focusing technology dates back to the LDRD-supported High Energy Focusing Telescope (HEFT) instrument, the success of which allowed Livermore to propose NuSTAR to NASA. The figure (courtesy of NASA/JPL-Caltech) depicts two theories on how to interpret the iron "fingerprints" in a black hole's accretion disk. NuSTAR has enabled researchers to rule out the bottom theory in favor of the top one—known as the rotation model—in which iron is spread out by distortion effects caused by the black hole's immense gravity, which in turn allows inference of the black hole's spin rate from the amount of distortion observed in the iron. Read More »