David Kirkpatrick

November 21, 2008

Los Alamos announces superconductivity news

The release:

Los Alamos Scientists See New Mechanism for Superconductivity

When materials are tuned to a critical point at absolute zero temperature, quantum effects dictate universal behavior in material properties. The presence of a singular point is revealed through its unusual electronic properties outside a new form of matter that hides the singularity.

Quantum Blackhole (in condensed matter): When materials are tuned to a critical point at absolute zero temperature, quantum effects dictate universal behavior in material properties. The presence of a singular point is revealed through its unusual electronic properties outside a new form of matter that hides the singularity.   enlarge image

Quantum

Quantum “Alchemy”: Formation of superconductivity in the vicinity of a singular critical point defies the conventional belief that turbulent electronic fluctuations are not beneficial to form the macroscopic quantum state. The unheralded source of superconductivity holds promise for the design of a room temperature superconductor.   enlarge image

LOS ALAMOS, N.M., November 24, 2008 — Laboratory researchers have posited an explanation for superconductivity that may open the door to the discovery of new, unconventional forms of superconductivity.

In a November 20 Nature letter, research led by Tuson Park and Joe D. Thompson describes a new explanation for superconductivity in non-traditional materials—one that describes a potentially new state of matter in which the superconducting material behaves simultaneously as a nonmagnetic material and a magnetic material.

Superconducting materials carry a current without resistance, usually when cooled to temperatures nearing the liquid point of helium (nearly 452 degrees below zero Fahrenheit). Superconductors are extremely important materials because they hold promise for carrying electricity from one place to another without current loss or providing indefinite electric storage capacity. However, the cost of cooling materials to such extremely low temperatures currently limits the practicality of superconductors. If superconductors could be designed to operate at temperatures closer to room temperature, the results would be revolutionary.

Traditional theories of superconductivity hold that electrons within certain nonmagnetic materials can pair up when jostled together by atomic vibrations known as phonons. In other words, phonons provide the “glue” that makes superconductivity possible.

Park and his colleagues now describe a different type of “glue” giving rise to superconducting behavior.

Park and his colleagues cooled a compound of Cerium, Rhodium and Indium to just above absolute zero, nearly minus 459 degrees Fahrenheit. At this temperature, the material exhibits superconducting behavior. However, they also subjected the crystal to pressure changes and a magnetic field to perturb the alignment of electrons within the material.

“We introduced very high quantum fluctuations in the material,” Park said. “In other words, we made the electrons like a traffic jam, where it would be very difficult for them to move.”

This electronic traffic jam would discourage electron pairing by phonons; nevertheless, the material continued to exhibit superconducting behavior.

Based on the material’s behavior under different pressures and temperatures, researchers believe that the material reaches a quantum critical point near absolute zero. At this quantum critical point, the material retained properties of a metal with highly ordered electrons and highly disordered ones—a previously undescribed state of matter.

Park and his colleagues believe that this quantum critical point provides a mechanism to pair electrons into a quantum state that gives rise to superconducting behavior. In other words, the research helps explain a mechanism for superconductivity without phonons.

“This quantum critical point could be analogous to a black hole,” said Park. “We can see what is happening at or near the event horizon—superconductivity—but we cannot yet see inside to understand why.”

A new mechanism for the electron-pairing glue that gives rise to superconductivity could allow researchers to design new materials that exhibit superconducting materials at higher temperatures, perhaps even opening the door to the “Holy Grail” of superconducting materials—one that works at room temperature.

Park’s colleagues include: Vladimir Sidorov, Filip Ronning, Jian-Xin Zhu, Yoshifumi Tokiwa, Hanoh Lee, Eric Bauer, Roman Movshovich, John Sarrao and Joe D. Thompson.

The research was supported by the U.S. Department of Energy’s Office of Science and Office of Basic Energy Science and funded in part by Los Alamos National Laboratory.

 

Los Alamos National Laboratory, a multidisciplinary research institution engaged in strategic science on behalf of national security, is operated by Los Alamos National Security, LLC, a team composed of Bechtel National, the University of California, The Babcock & Wilcox Company, and Washington Group International for the Department of Energy’s National Nuclear Security Administration.

Los Alamos enhances national security by ensuring the safety and reliability of the U.S. nuclear stockpile, developing technologies to reduce threats from weapons of mass destruction, and solving problems related to energy, environment, infrastructure, health, and global security concerns.

November 18, 2008

Billions of anti-matter particles

Very interesting research.

The release:

Billions of particles of anti-matter
created in laboratory

LIVERMORE, Calif. – Take a gold sample the size of the head of a push pin, shoot a laser through it, and suddenly more than 100 billion particles of anti-matter appear.

The anti-matter, also known as positrons, shoots out of the target in a cone-shaped plasma “jet.”

This new ability to create a large number of positrons in a small laboratory opens the door to several fresh avenues of anti-matter research, including an understanding of the physics underlying various astrophysical phenomena such as black holes and gamma ray bursts.

Anti-matter research also could reveal why more matter than anti-matter survived the Big Bang at the start of the universe.

“We’ve detected far more anti-matter than anyone else has ever measured in a laser experiment,” said Hui Chen, a Livermore researcher who led the experiment. “We’ve demonstrated the creation of a significant number of positrons using a short-pulse laser.”

Chen and her colleagues used a short, ultra-intense laser to irradiate a millimeter-thick gold target. “Previously, we concentrated on making positrons using paper-thin targets,” said Scott Wilks, who designed and modeled the experiment using computer codes. “But recent simulations showed that millimeter-thick gold would produce far more positrons. We were very excited to see so many of them.”

In the experiment, the laser ionizes and accelerates electrons, which are driven right through the gold target. On their way, the electrons interact with the gold nuclei, which serve as a catalyst to create positrons. The electrons give off packets of pure energy, which decays into matter and anti-matter, following the predictions by Einstein’s famous equation that relates matter and energy. By concentrating the energy in space and time, the laser produces positrons more rapidly and in greater density than ever before in the laboratory.

“By creating this much anti-matter, we can study in more detail whether anti-matter really is just like matter, and perhaps gain more clues as to why the universe we see has more matter than anti-matter,” said Peter Beiersdorfer, a lead Livermore physicist working with Chen.

Particles of anti-matter are almost immediately annihilated by contact with normal matter, and converted to pure energy (gamma rays). There is considerable speculation as to why the observable universe is apparently almost entirely matter, whether other places are almost entirely anti-matter, and what might be possible if anti-matter could be harnessed. Normal matter and anti-matter are thought to have been in balance in the very early universe, but due to an “asymmetry” the anti-matter decayed or was annihilated, and today very little anti-matter is seen.

Over the years, physicists have theorized about anti-matter, but it wasn’t confirmed to exist experimentally until 1932. High-energy cosmic rays impacting Earth’s atmosphere produce minute quantities of anti-matter in the resulting jets, and physicists have learned to produce modest amounts of anti-matter using traditional particle accelerators. Anti-matter similarly may be produced in regions like the center of the Milky Way and other galaxies, where very energetic celestial events occur. The presence of the resulting anti-matter is detectable by the gamma rays produced when positrons are destroyed when they come into contact with nearby matter.

Laser production of anti-matter isn’t entirely new either. Livermore researchers detected anti-matter about 10 years ago in experiments on the since-decommissioned Nova “petawatt” laser – about 100 particles. But with a better target and a more sensitive detector, this year’s experiments directly detected more than 1 million particles. From that sample, the scientists infer that around 100 billion positron particles were produced in total.

Until they annihilate, positrons (anti-electrons) behave much like electrons (just with an opposite charge), and that’s how Chen and her colleagues detected them. They took a normal electron detector (a spectrometer) and equipped it to detect particles with opposite polarity as well.

“We’ve entered a new era,” Beiersdorfer said. “Now, that we’ve looked for it, it’s almost like it hit us right on the head. We envision a center for antimatter research, using lasers as cheaper anti-matter factories.”

Chen will present her work at the American Physical Society’s Division of Plasma Physics meeting Nov. 17-21 at the Hyatt Regency Reunion in Dallas. S.C. Wilks, E. Liang, J. Myatt, K. Cone ,L. Elberson, D.D. Meyerhofer, M. Schneider, R. Shepherd, D. Stafford, R. Tommasini, P. Beiersdorfer are the collaborators on this project.

Founded in 1952, Lawrence Livermore National Laboratory is a national security laboratory, with a mission to ensure national security and apply science and technology to the important issues of our time. Lawrence Livermore National Laboratory is managed by Lawrence Livermore National Security, LLC for the U.S. Department of Energy’s National Nuclear Security Administration.

November 14, 2008

First images of new multi-planet solar system

The release:

Astronomers capture first images of
newly-discovered solar system

LIVERMORE, Calif. — Astronomers for the first time have taken snapshots of a multi-planet solar system, much like ours, orbiting another star.

The new solar system orbits a dusty young star named HR8799, which is 140 light years away and about 1.5 times the size of our sun. Three planets, roughly 10, 10 and 7 times the mass of Jupiter, orbit the star. The size of the planets decreases with distance from the parent star, much like the giant planets do in our system.

And there may be more planets out there, but scientists say they just haven’t seen them yet.

“Every extrasolar planet detected so far has been a wobble on a graph. These are the first pictures of an entire system,” said Bruce Macintosh, an astrophysicist from Lawrence Livermore National Laboratory and one of the key authors of a paper appearing in the Nov. 13 issue of Science Express.We’ve been trying image planets for eight years with no luck and now we have pictures of three planets at once.”

Using high-contrast, near-infrared adaptive optics observations with the Keck and Gemini telescopes, the team of researchers from Livermore, the NRC Herzberg Institute of Astrophysics in Canada, Lowell Observatory, University of California Los Angeles, and several other institutions were able to see three orbiting planetary companions to HR8799.

Astronomers have known for a decade through indirect techniques that the sun was not the only star with orbiting planets.

“But we finally have an actual image of an entire system,” Macintosh said. “This is a milestone in the search and characterization of planetary systems around stars.”

During the past 10 years, various planet detection techniques have been used to find more than 200 exoplanets. But these methods all have limitations. Most infer the existence of a planet through its influence on the star that it orbits, but don’t actually tell scientists anything about the planet other than its mass and orbit. Second, the techniques are all limited to small to moderate planet-star separation, usually less than about 5 astronomical units (one AU is the average distance from the sun to Earth).

In the new findings, the planets are 24, 37 and 67 times the Earth-sun separation from the host star. The furthest planet in the new system orbits just inside a disk of dusty debris, similar to that produced by the comets of the Kuiper belt of our solar system (just beyond the orbit of Neptune at 30 times Earth-sun distance).

“HR8799’s dust disk stands out as one of the most massive in orbit around any star within 300 light years of Earth” said UCLA’s Ben Zuckerman.

In some ways, this planetary system seems to be a scaled-up version of our solar system orbiting a larger and brighter star, Macintosch said.

The host star is known as a bright, blue A-type star. These types of stars are usually ignored in ground and space-based direct imaging surveys since they offer a less favorable contrast between a bright star and a faint planet. But they do have an advantage over our sun: Early in their life, they can retain heavy disks of planet-making material and therefore form more massive planets at wider separations that are easier to detect. In the recent study, the star also is young – less than 100 million years old – which means its planets are still glowing with heat from their formation.

“Seeing these planets directly – separating their light from the star – lets us study them as individuals, and use spectroscopy to study their properties, like temperature or composition,” Macintosh said.

“Detailed comparison with theoretical model atmospheres confirms that all three planets possess complex atmospheres with dusty clouds partially trapping and re-radiating the escaping heat” said Lowell Observatory astronomer Travis Barman.

The planets have been extensively studied using adaptive optics on the giant Keck and Gemini telescopes on Mauna Kea, Hawaii. Adaptive optics enables astronomers to minimize the blurring effects of the Earth’s atmosphere, producing images with unprecedented detail and resolution. LLNL helped build the original adaptive optics system for Keck, the world’s largest optical telescope. Christian Marois, a former LLNL postdoctoral researcher and the primary author of the paper who now works at NRC, developed an advanced computer processing technique that helps to extract the planets from the vastly brighter light of the star.

A team led by Macintosh is constructing a much more advanced adaptive optics system designed from the beginning to block the light of bright stars and reveal even fainter planets. Known as the Gemini Planet Imager (http://gpi.berkeley.edu), this new system will be up to 100 times more sensitive than current instruments and able to image planets similar to our own Jupiter around nearby stars.

“I think there’s a very high probability that there are more planets in the system that we can’t detect yet,” Macintosh said. “One of the things that distinguishes this system from most of the extrasolar planets that are already known is that HR8799 has its giant planets in the outer parts – like our solar system does – and so has ‘room’ for smaller terrestrial planets – far beyond our current ability to see – in the inner parts.”

Founded in 1952, Lawrence Livermore National Laboratory is a national security laboratory, with a mission to ensure national security and apply science and technology to the important issues of our time. Lawrence Livermore National Laboratory is managed by Lawrence Livermore National Security, LLC for the U.S. Department of Energy’s National Nuclear Security Administration.

Near-infrared false-color image taken with the W.M. Keck II telescope and adaptive optics. The three planets are labelled b, c, and d. The colored speckles in the center are the remains of the bright light from their parent star after image processing.

Near-infrared false-color image taken with the W.M. Keck II telescope and adaptive optics. The three planets are labelled b, c, and d. The colored speckles in the center are the remains of the bright light from their parent star after image processing.

April 8, 2008

Breaking the petawatt laser barrier

Filed under: Science — Tags: , , , — David Kirkpatrick @ 2:25 am

Yowza. In a release today the University of Texas announced the Texas Petawatt laser exceeded one petawatt of power on March 31.

The release:

Most powerful laser in the world fires up

AUSTIN, Texas—The Texas Petawatt laser reached greater than one petawatt of laser power on Monday morning, March 31, making it the highest powered laser in the world, Todd Ditmire, a physicist at The University of Texas at Austin, said.

The Texas Petawatt is the only operating petawatt laser in the United States.

Ditmire says that when the laser is turned on, it has the power output of more than 2,000 times the output of all power plants in the United States. (A petawatt is one quadrillion watts.) The laser is brighter than sunlight on the surface of the sun, but it only lasts for an instant, a 10th of a trillionth of a second (0.0000000000001 second).

Ditmire and his colleagues at the Texas Center for High-Intensity Laser Science will use the laser to create and study matter at some of the most extreme conditions in the universe, including gases at temperatures greater than those in the sun and solids at pressures of many billions of atmospheres.

This will allow them to explore many astronomical phenomena in miniature. They will create mini-supernovas, tabletop stars and very high-density plasmas that mimic exotic stellar objects known as brown dwarfs.

“We can learn about these large astronomical objects from tiny reactions in the lab because of the similarity of the mathematical equations that describe the events,” said Ditmire, director of the center.

Such a powerful laser will also allow them to study advanced ideas for creating energy by controlled fusion.

 

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The Texas Petawatt was built with funding provided by the National Nuclear Security Administration, an agency within the U. S. Department of Energy.