From SLAC: “KIPAC Theorists Weigh In on Where to Hunt Dark Matter”

May 21, 2013
Lori Ann White

Theorists from the Kavli Institute for Particle Astrophysics and Cosmology are helping dark matter sleuths decide where to start their search.

“Now that it looks like the hunt for the Higgs boson is over, particles of dark matter are at the top of the physics ‘Most Wanted’ list. Dozens of experiments have been searching for them, but often come up with contradictory results.

Theorists from the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC), a joint SLAC-Stanford institute, believe they’ve come up with an algorithm – a mathematical description of how the individual particles behave – that could help narrow the search for these elusive particles, which are thought to make up more than 25 percent of the matter and energy in the universe.

It starts with assumptions, said Yao-Yuan Mao, lead author of a paper published in The Astrophysical Journal that outlines their new search tool. Assumptions are a good starting point when you don’t know where to look. A popular assumption about dark matter is that it’s made up of WIMPs, Weakly Interacting Massive Particles. The “M” in WIMP accounts for gravity’s ability to herd these particles around; the “P” and “I” hint at why they’re so hard to detect otherwise.

KIPAC theorists (l to r) Louis Strigari, Risa Wechsler and Yao-Yuan Mao discussing dark matter velocity distributions. (Credit: Luis Fernandez.)

Most dark matter detectors are based on the assumption that, every once in a while, a WIMP must smack into the nucleus of an atom of visible matter, making the nucleus vibrate and releasing a signal. Such disruptions can be detected. But what that disruption looks like and how often it happens depends on yet more assumptions. How heavy is the dark matter particle? How fast is it moving?

Left panel: Air molecules whiz around at a variety of speeds, and some are very fast. When they collide with both heavy and light elements – for example, xenon (purple) and silicon (orange) – these fast moving particles have enough momentum to affect both nuclei. Right panel: Dark matter particles are moving more slowly and are less able to affect the heavy xenon nucleus. As a result, detectors made from lighter materials like silicon may prove to be more effective at picking up signals of dark matter. (Credit: Greg Stewart/SLAC National Accelerator Laboratory)

Another common assumption that touches on these issues, said Mao, is that collections of WIMPs behave as an ideal gas, a collection of particles that hang out together and occasionally bounce off each other. Sometimes a lucky bounce gives a particle more energy, sending it zooming off at a greater speed. How often particles pick up more energy and more speed depends on how much you turn up the heat or put on the pressure.

But, as far as scientists can tell, turning up the heat and putting on the pressure doesn’t affect WIMPs. Only gravity does.

“The Ideal Gas Law doesn’t describe a system of particles, like dark matter particles, that don’t seem to transfer energy to each other,” said Mao. This incorrect description can distort the carefully built picture upon which a search for WIMPs is based. In particular, it means predictions of their velocities can be off by a significant amount, but velocities affect what a detector will see.

Mao and his colleagues have used simulations to provide new insight into how fast WIMPs are expected to move.”

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 Brookhaven Lab: “Atomic-Scale Investigations Solve Key Puzzle of LED Efficiency”

Brookhaven Lab

MIT and Brookhaven Lab scientists use electron microscopy imaging techniques to settle a solid-state controversy and raise new experimental possibilities

May 22, 2013
Contacts: Justin Eure, (631) 344-2347 or Peter Genzer, (631) 344-3174

“From the high-resolution glow of flat screen televisions to light bulbs that last for years, light-emitting diodes (LEDs) continue to transform technology. The celebrated efficiency and versatility of LEDs—and other solid-state technologies including laser diodes and solar photovoltaics—make them increasingly popular. Their full potential, however, remains untapped, in part because the semiconductor alloys that make these devices work continue to puzzle scientists.

CFN’s Kim Kisslinger, seen here with a focused-ion beam instrument, reduced the InGaN samples to a thickness of just 20 nanometers to prepare them for electron microscopy.

A contentious controversy surrounds the high intensity of one leading LED semiconductor—indium gallium nitride (InGaN)—with experts split on whether or not indium-rich clusters within the material provide the LED’s remarkable efficiency. Now, researchers from the Massachusetts Institute of Technology (MIT) and the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory have demonstrated definitively that clustering is not the source. The results—published online May 16 in Applied Physics Letters—advance fundamental understanding of LED technology and open new research pathways.

‘This discovery helps solve a significant mystery in the field of LED research and demonstrates breakthrough experimental techniques that can advance other sensitive and cutting-edge electronics,’ said Silvija Gradečak, the Thomas Lord Associate Professor of Materials Science and Engineering at MIT and a coauthor on the study. ‘The work brings us closer to truly mastering solid-state technologies that could supply light and energy with unprecedented efficiency.’

The research was supported by the Center for Excitonics, an Energy Frontier Research Center funded by the U.S. Department of Energy’s Office of Science. The work at Brookhaven Lab’s Center for Functional Nanomaterials was also supported by DOE’s Office of Science, with additional work carried out at the MIT Center for Materials Science Engineering.”

This scanning transmission electron microscope’s non-destructive imaging of specific InGaN samples clarified a decade of research, demonstrating conclusively that indium-rich clustering does not drive the efficient light emission.

These images of the InGaN samples—produced by CFN’s low-voltage scanning transmission electron microscope—reveal a lack of structural changes over time. After 16 minutes of scanning, no damage or decomposition is visible, and the higher magnification (c) exhibits none of the clustering previously theorized to be central to LED efficiency

See the full article here. There is a ton of interesting information here.

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. 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.

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From Berkeley Lab: “Whirlpools on the Nanoscale Could Multiply Magnetic Memory”

Berkeley Lab

At the Advanced Light Source, Berkeley Lab scientists join an international team to control spin orientation in magnetic nanodisks

May 21, 2013
Paul Preuss 510-486-6249 paul_preuss@lbl.gov

‘We spent 15 percent of home energy on gadgets in 2009, and we’re buying more gadgets all the time,’ says Peter Fischer of the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab). Fischer lets you know right away that while it’s scientific curiosity that inspires his research at the Lab’s Advanced Light Source (ALS), he intends it to help solve pressing problems.

The electron spins in a magnetic vortex all point in parallel, either clockwise or counterclockwise. Spins in the crowded core of the vortex must point out of the plane, either up or down. The four orientations of circularity and polarity could form the cells of multibit magnetic storage and processing systems.

‘What we’re working on now could make these gadgets perform hundreds of times better and also be a hundred times more energy efficient,’ says Fischer, a staff scientist in the Materials Sciences Division. As a principal investigator at the Center for X-Ray Optics, he leads ALS beamline 6.1.2, where he specializes in studies of magnetism.

Fischer recently provided critical support to a team led by Vojtĕch Uhlíř of the Brno University of Technology in the Czech Republic and the Center for Magnetic Recording Research at the University of California, San Diego. Researchers from both institutions and from Berkeley Lab used the unique capabilities of beamline 6.1.2 to advance a new concept in magnetic memory.

‘Magnetic memory is at the heart of most electronic devices,’ says Fischer, ‘and from the scientist’s point of view, magnetism is about controlling electron spin.’

Magnetic memories store bits of information in discrete units whose electron spins all line up in parallel, pointing one way or the opposite to signify a one or a zero. What Fischer and his colleagues propose is multibit storage in which each unit has four states instead of two and can store twice the information.

See the full article here. This may effect a lot of what you do.

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

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From Argonne APS: “Nanocrystals Grow from Liquid Interface”

Argonne National Laboratory

MAY 20, 2013

“Liquid interface behavior cannot be investigated at atomic level by most modern methods. Only brilliant X-rays at world-leading light sources can investigate this type of important chemical processes.

Illustration of the nano-layer at the liquid interface between the salt solution and mercury. Physicists from Kiel University discovered the formation of an ordered crystal of exactly five atomic layers between the two liquids with brilliant X-rays. Image courtesy Christian-Albrechts-Universität zu Kiel.

The result is reported on in the April issue of the journal Proceedings of the National Academy of Science in an article titled In situ x-ray studies of adlayer-induced crystal nucleation at the liquid-liquid interface.

The team used high-energy, high-brilliance X-rays at the LSS (liquid surface spectrometer) at the 9-ID-C beamline of the U.S. Department of Energy Office of Science’s Advanced Photon Source at Argonne National Laboratory and the LISA diffractometer (Liquid Interfaces Scattering Apparatus) at the PETRA III light source at the German laboratory DESY. The research is the continuation and expansion of research done at the APS in 2010.

In their latest work, the researchers from the U.S., Israel and Germany wanted to find out, for the first time, what exactly occurs during chemical growth at liquid interfaces. Led by researchers from the Institute of Experimental and Applied Physics of Kiel University, the team observed the formation of an ordered crystal of exactly five atomic layers between the two liquids, which acts as a foundation for growing even bigger crystals. This work may result in new semiconductor and nanoparticle production processes.”

See the full article here.

Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science

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From Brookhaven Lab: “Soaking Up Sun at the Long Island Solar Farm for Energy Research at Brookhaven Lab”

Brookhaven Lab

May 16, 2013
Pat Looney

“Bring on the sunshine! April showers are behind us and the sun is shining a little longer each day in the northern hemisphere. That means the 200-acre Long Island Solar Farm (LISF) at Brookhaven Lab is producing increasing amounts of renewable energy for Long Islanders and data for our researchers.

The 200-acre Long Island Solar Farm (LISF) is located at the east end of Brookhaven Lab. By hosting the LISF and future Northeast Solar Energy Research Center on site, Brookhaven Lab has positioned itself at the forefront of new research to help develop real-world solar energy technologies.

The LISF is the largest solar array in the eastern U.S. and is located at the east end of the Lab site. It contains 164,312 photovoltaic panels grouped and mounted onto more than 6,800 racks. The LISF can produce peak power output of 32 megawatts (MW) of alternating current that powers homes and businesses. Operations began in November 2011, and during its first 12 months, the LISF produced a total of about 54,000 megawatt-hours (MWH) of energy. That’s 23 percent more than the design estimates for 44,000 MWH, which is equivalent to the power usage for about 4,500 homes.

LISF, LLC—a joint venture between BP Solar and Met Life—owns the array and LIPA purchases the electrical output, distributes it, and sells it to customers. BP Solar has announced its intention to exit the solar energy business and we expect it to sell its share to another party, but this would not affect operations or agreements with Brookhaven and the U.S. Department of Energy (DOE). While the Laboratory doesn’t get any electricity from the LISF, it does get large amounts of data from operations. The Lab will get both electricity and research data from the Northeast Solar Energy Research Center (NSERC) being developed on site. By hosting both arrays here, the Lab has positioned itself at the forefront of new research to help develop real-world solar energy technologies.”

See the full and very enlightening article here.

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. 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.

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From SLAC: “Earth’s iron core is surprisingly weak, Stanford researchers say”

The researchers used a diamond anvil cell to squeeze iron at pressures as high as 3 million times that felt at sea level to recreate conditions at the center of Earth. The findings could refine theories of how the planet and its core evolved.

May 16, 2013
Louis Bergeron

“The massive ball of iron sitting at the center of Earth is not quite as “rock-solid” as has been thought, say two Stanford mineral physicists. By conducting experiments that simulate the immense pressures deep in the planet’s interior, the researchers determined that iron in Earth’s inner core is only about 40 percent as strong as previous studies estimated.

Through laboratory experiments, postdoctoral researcher Arianna Gleason, left, and Wendy Mao, an assistant professor of geological and environmental sciences and of photon science, determined that the iron in Earth’s inner core is about 40 percent as strong as previously believed.

This is the first time scientists have been able to experimentally measure the effect of such intense pressure – as high as 3 million times the pressure Earth’s atmosphere exerts at sea level – in a laboratory. A paper presenting the results of their study is available online in Nature Geoscience.

Until now, almost all of what is known about Earth’s inner core came from studies tracking seismic waves as they travel from the surface of the planet through the interior. Those studies have shown that the travel time through the inner core isn’t the same in every direction, indicating that the inner core itself is not uniform. Over time and subjected to great pressure, the core has developed a sort of fabric as grains of iron elongate and align lengthwise in parallel formations.

Gleason and Mao conducted their experiments using a diamond anvil cell – a device that can exert immense pressure on tiny samples clenched between two diamonds. They subjected minute amounts of pure iron to pressures between 200 and 300 gigapascals (equivalent to the pressure of 2 million to 3 million Earth atmospheres). Previous experimental studies were conducted in the range of only 10 gigapascals.

Gleason and Mao expect their findings will help other researchers set more realistic variables for conducting their own experiments.”

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 Stanford: “Stanford physicists develop revolutionary low-power polariton laser”

Stanford University

May 20, 2013
Thomas Sumner

“Lasers are an unseen backbone of modern society. They’re integral to technologies ranging from high-speed Internet services to Blu-ray players.

Physicist Na Young Kim, at the optical bench, is a member of the international team that has demonstrated a revolutionary electrically driven polariton laser that could significantly improve the efficiency of lasers.

The physics powering lasers, however, has remained relatively unchanged through 50 years of use. Now, an international research team led by Stanford’s Yoshihisa Yamamoto, a professor of electrical engineering and of applied physics, has demonstrated a revolutionary electrically driven polariton laser that could significantly improve the efficiency of lasers.

The system makes use of the unique physical properties of bosons, subatomic particles that scientists have attempted to incorporate into lasers for decades.

‘We’ve solidified our physical understanding, and now it’s time we think about how to put these lasers into practice, said physicist Na Young Kim, a member of the Stanford team. ‘This is an exciting era to imagine how this new physics can lead to novel engineering.’
“

This is truly revolutionary. See the full article here.

Leland and Jane Stanford founded the University to “promote the public welfare by exercising an influence on behalf of humanity and civilization.” Stanford opened its doors in 1891, and more than a century later, it remains dedicated to finding solutions to the great challenges of the day and to preparing our students for leadership in today’s complex world. Stanford, is an American private research university located in Stanford, California on an 8,180-acre (3,310 ha) campus near Palo Alto. Since 1952, more than 54 Stanford faculty, staff, and alumni have won the Nobel Prize, including 19 current faculty members

From Brookhaven : “DNA-Guided Assembly Yields Novel Ribbon-Like Nanostructures”

Brookhaven Lab

Approach could be useful in fabricating new kinds of materials with engineered properties

May 16, 2013
Contacts: Karen McNulty Walsh, (631) 344-8350 or Peter Genzer, (631) 344-3174

“Scientists at the U.S. Department of Energy’s Brookhaven National Laboratory have discovered that DNA “linker” strands coax nano-sized rods to line up in way unlike any other spontaneous arrangement of rod-shaped objects. The arrangement—with the rods forming “rungs” on ladder-like ribbons linked by multiple DNA strands—results from the collective interactions of the flexible DNA tethers and may be unique to the nanoscale. The research, described in a paper published online in ACS Nano, a journal of the American Chemical Society, could result in the fabrication of new nanostructured materials with desired properties.

DNA-tethered nanorods link up like rungs on a ribbonlike ladder—a new mechanism for linear self-assembly that may be unique to the nanoscale.
‘This is a completely new mechanism of self-assembly that does not have direct analogs in the realm of molecular or microscale systems,’ said Brookhaven physicist Oleg Gang, lead author on the paper, who conducted the bulk of the research at the Lab’s Center for Functional Nanomaterials (CFN).

Alexei Tkachenko, the CFN scientist who developed the theory to explain the exceptional arrangement, elaborated: ‘Remarkably, the system has all three dimensions to live in, yet it chooses to form the linear, almost one-dimensional ribbons. It can be compared to how extra dimensions that are hypothesized by high-energy physicists become hidden, so that we find ourselves in a 3-D world.’

Schematic of how gold nanorods link up when complementary strands of DNA attached to each rod (A, A’)—or DNA linker strands with ends complementary to two different types of DNA tethers on adjacent rods (B, C)—are used as “glue.”

See the full article here. There is much more.

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. 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.

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From Berkeley Lab: “Brain Visualization Prototype Holds Promise for Precision Medicine”

Berkeley Lab

From the Computational Research Division

Berkeley Lab, UCSF and Oblong Industries Show Brain Browser at Summit

“The ability to combine all of a patient’s neurological test results into one detailed, interactive “brain map” could help doctors diagnose and tailor treatment for a range of neurological disorders, from autism to epilepsy. But before this can happen, researchers need a suite of automated tools and techniques to manage and make sense of these massive complex datasets.

Computational researchers from Berkeley Lab used existing computational tools to translate laboratory data collected at UCSF into 3D visualizations of brain structures and activity.

To get an idea of what these tools would look like, computational researchers from the Lawrence Berkeley National Laboratory (Berkeley Lab) are working with neuroscientists from the University of California, San Francisco (UCSF). So far, the Berkeley Lab team has used existing computational tools to translate UCSF laboratory data into 3D visualizations of brain structures and activity. Earlier this year, Los Angeles-based Oblong Industries joined the collaboration and implemented a state-of-the-art, gesture-based navigation interface that allows researchers to interactively explore 3D brain visualizations with hand poses movements.

This is terrific new science.

See the full article here.

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

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From Berkeley Lab: “Comparing Proteins at a Glance”

Berkeley Lab

Berkeley Lab Researchers Unveil Technique for Easy Comparisons of Proteins in Solution

April 29, 2013
Lynn Yarris (510) 486-5375 lcyarris@lbl.gov

“A revolutionary X-ray analytical technique that enables researchers at a glance to identify structural similarities and differences between multiple proteins under a variety of conditions has been developed by researchers with the U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab). As a demonstration, the researchers used this technique to gain valuable new insight into a protein that is a prime target for cancer chemotherapy.

Data in this revolutionary structural comparison map is presented as a color-coded checkerboard with similarity scores displayed as gradients moving from red, indicating high, to white, indicating low, and various shades of orange and yellow in between. No image credit

‘Proteins and other biological macromolecules are moving machines whose power is often derived from how their structural conformations change in response to their environment,’ says Greg Hura, a scientist with Berkeley Lab’s Physical Biosciences Division. ‘Knowing what makes a protein change has incredible value, much like knowing that stepping on a gas pedal makes the wheels of a car spin.’

Hura led the development of what is being called a structural comparison map for use with small angle X-ray scattering
(SAXS), an imaging technique for obtaining structural information about proteins and protein complexes in solution. Cynthia McMurray, a biologist with Berkeley Lab’s Life Sciences Division, provided the cancer-relevant protein used to test the new SAXS structural comparison map.

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

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