Waves & Packets
May. 26, 2012

Square Kilometer Array board makes decision: Africa and Australasia to share telescope
"We have decided on a dual site approach," said SKA board Chairman John Wommersley at a press conference following a meeting of the SKA organization's members. The SKA is a $2 billion mega-project to build the world's most sensitive radio telescope consisting of 3,000 separate dishes spread out over thousands of kilometers. The project planning has been ongoing for nearly 20 years. After a global competition to host the telescope, a partnership of eight African countries led by South Africa, and a partnership between Australia and New Zealand emerged as the two finalists. Two months ago, the SKA Site Selection Advisory Committee issued its confidential report. Several news stories on the report's contents, including a press report by Nature News, had indicated that the committee's recommendation was that the project be awarded to the African partners. Under the SKA board's May 25 decision, Africa will host more than two-thirds of the 3,000 dishes. The official announcement indicates that the Australian/New Zealand facility will work at low frequencies while the African array will work at midfrequencies. More

Comments sought on the Next Generation Science Standards
Education Week
Public comments on the science component of the Common Core School Standards Initiative are being solicited until June 1. The "Common Core" is a project of the National Governors Association and the Council of Chief State School Officers to standardize learning standards across the United States. The mathematics and English Language Arts components were released in 2010. The so-called Next Generation Science Standards were released on May 11. An understanding of the Framework for K-12 Science Education is crucial to be able to critically review the NGSS. This framework was developed by National Academy of Sciences panel chaired by former American Physical Society president, Helen Quinn. The NGSS are consistent with the curricular strategy of "Physics First," which was endorsed by NSBP and the National Alliance of Black School Educators earlier this year as a way to address issues of equity and access to opportunities to learn physics. Currently only a quarter of African American high school students take a high school physics course.More

Astronomers create early warning system for stellar explosions with citizen-scientist participation
The entire sky cannot be monitored constantly. So astronomers have created the SuperNova Early Warning System — a worldwide network of neutrino observatories that looks for neutrino showers, the telltale signs that a galactic supernova is about to become visible. The system consists of a network of neutrino detectors connected to a central server at Brookhaven National Laboratory. When a valid signal is obtained by the server indicating a neutrino shower seen by more than one detector, an alert is sent to the SNEWS community, which includes professional and amateur astronomers. Anyone can sign up to be alerted by SNEWS when a supernova is detected.More

Exotic particles, chilled and trapped, form giant matter wave
University of California San Diego
Physicists have trapped and cooled excitons so effectively that they condensed and cohered to form a giant matter wave. Excitons are composite particles made up of a coupled pair containing an electron and a "hole" left by a missing electron in a semiconductor. They are often created by light, and their formation and dynamics play a critical role in photosynthesis. Scientists can easily create excitons by shining light on a semiconductor. But the key to the team's success was to separate the electrons far enough from their holes so that excitons could last long enough to be cooled to as cold as 50 milli-Kelvin in an optical dilution refrigerator. Whole atoms have been trapped and cooled in the manner before, but this is the first time that scientists have seen subatomic particles form coherent matter waves in a trap. A report on this work is published in Nano Letters. More

Topological insulators open up a path to room-temperature spintronics
Lawrence Berkeley National Lab
Strong three dimensional topological insulators — experimentally discovered just a few years ago — are driving new vistas in condensed matter physics research. Topical insulators can be imagined as being insulators in their interiors, but having a conductive thin shell at the surface. But there is more to it than that. The direction and spin of the surface electrons are locked together and change in concert. The mobile electrons cannot be scattered by defects or other perturbations, and they meet little to no resistance as they travel. A recent angle-resolved photoemission spectrometry study of Bi2Se3, published in Physical Review Letters, revealed a Dirac point between the valence and conduction bands, similar to that found in graphene. But unlike graphene the spin-locking property of TIs is clearly evident from their Fermi surfaces.More

Physicists crate low-power all-optical switch
University of Maryland
Physicists at the Maryland-NIST Joint Quantum Institute have developed a switch that can steer a beam of light from one direction to another in only 120 picoseconds and requires very little power. This new switch consists of a quantum dot of indium and arsenic placed inside a resonant cavity. The quantum dot sits inside a photonic crystal that only transmits light in a narrow wavelength band. Previous optical switches have been able to work only by using bulky nonlinear-crystals and high input power. But so far, this milestone can only be achieved at 40 K, whereas higher power similar switches work at room temperature.More

Electron spin influences nanotube motion
American Physical Society
Theoretical work reported in Physical Review Letters demonstrates that the spin of a single electron trapped on a carbon nanotube may influence — and be influenced by — the vibrations of the nanotube via spin-orbit coupling. Delocalized electrons on carbon nanotubes follow circular orbits around the tube circumference. The orbit of the electron is affected by, and affects, the lattice geometry. Because of the strong spin-orbit coupling, the electron's spin can switch direction under the influence of an external magnetic field. In order to maximize the effect on the spin, the researchers found that the magnetic field strength must be set so that the energy difference between the two spin states matches the energy of the nanotube vibration. More

Researchers use carbon nanotubes to develop uncooled infrared detector
A team of researchers from Peking University, Duke University and the Chinese Academy of Sciences fabricated an "uncooled" ultrasensitive photovoltaic infrared detector using single-walled carbon nanotubes. Compared to conventional IR detectors based on mercury-cadmium-telluride alloy, carbon nanotube IR detectors are more efficient because the IR absorption can be tailored just by changing the diameter of the tube, and the response only takes a matter of picoseconds. This new detector does not require electric or liquid nitrogen cooling thanks to the thermal properties of carbon nanotubes, which are good heat conductors and release minimal IR radiation. The sensor design and performance are reported in Optical Materials Express, an open-access journal of the Optical Society of America.More

Deconstructing the quark-gluon plasma
American Physical Society
Quark-gluon plasmas result from relativistic collisions of atomic nuclei and is a state of matter that exists but mere fractions of a second before the strong force condenses the quarks and gluons into protons, neutrons and other stable hadrons. QGP is thought to be the primordial state of matter that existed just at the instant of the Big Bang. Using various known results from lattice quantum chromodynamics simulations, a researcher from Michigan State University has proposed a precise relationship between the charge correlations of the quarks and gluons and statistical correlations between the spatial distributions of the measured hadrons. The proposal, published in Physical Review Letters, can in principle be tested against data from experiments at the Large Hadron Collider and the Relativistic Heavy Ion Collider. More

The state of particle physics — a report from Pheno 2012
Ars Technica
Science writer and Ph.D. physicist Matthew Francis recently attended the Phenomenology 2012 conference. He reports that no new results were announced, and to him, the conference provided a good overview of the state of particle physics. The LHC has already produced as many collisions as it had at the end of July last year, and the 2012 run of the LHC will increase the amount of data in the hunt for the Higgs by a factor of 10. Though the data so far points to a Higgs particle near 125 Gev, wise physicists are hedging their bets. Big problems loom in the theories that explain the results. The Standard Model does not predict exactly what the Higgs mass should be. Supersymmetry, a Standard Model extension, predicts a mass range for the Higgs boson that is much greater than 125 GeV. Supersymmetric particles, postulated to exist in SUSY, have not yet been detected. These particles could be a good explanation for dark matter. But the simplest form of the theory does not comport with the data, which means there are opportunities to develop more complex theories and uncover new physics.More

Deep underground, LUX lies in wait for WIMPs
R&D Magazine
LUX, the Large Underground Xenon detector at the Sanford Underground Research Facility in the Black Hills of South Dakota, is set to look for weakly interacting massive particles, or WIMPs. Because of the observed effects ascribed to dark matter, it has to be massive. But dark matter must be only weakly interacting; otherwise it would not be invisible. In the LUX experiment scintillation in xenon is used to detect WIMPs as they collide with xenon atoms. LUX ZEPLIN is a scaled-up version of LUX, plus it has a nested tank design that will allow scientists to count more scintillation events as true data. Because the properties of WIMPs are still theoretical, finding them depends on hypothetical characteristics such as their mass and spin. Detectors like LUX aren't the only way to look for WIMPs. If, as many theorists propose, they are supersymmetric particles unlike anything in the Standard Model, it may be able to create them with the Large Hadron Collider.More

A boost for quantum reality: Theorists claim they can prove that wavefunctions are real states
Nature News
The online discussion of a paper claiming to show mathematically that the wavefunction is real has ranged from ardently star-struck to downright vitriolic since the article was first released as a preprint in November 2011. The paper, thought by some to be one of the most important in quantum foundations in decades, was recently published in Nature Physics. Philosophically the wavefunction either represents a real state that is a probabilistic distribution of possible states, or it is representation of a state that cannot actually be known. This new result shows that theories that treat the wavefunction in terms of lack of knowledge of a system's physical state will fail to reproduce foundational predictions in quantum mechanics, and that that the same reality cannot underpin different quantum states.More

National Society of Black Physicists jobs board postings
Advanced Topics in Astrostatistics
Biophotonic Solutions 2012 MIIPS Ultrafast Pulse Shaping Workshop
Faculty Positions in Science, Technology and Innovation
Research Datacenter and Computing Infrastructure Manager
SKA Project Scientist
Women's Business Enterprise National Council Student Program
3x Senior Astronomers — SKA Africa
Nanoscale Measurements For Soft Matter Systems
NASA Postdoctoral Fellowships
National Astrophysics and Space Science Program
Postdoctoral Research Associate PositionsMore

Latest research from Semiconductor Science and Technology
IOP Journal
Experimental and modelling investigation of the influence of noise transit time and self-heating on microwave noise of Si/SiGe:C and InP/InGaAs HBTs

Tunneling currents in a spherically shaped MIS structure

Kink effect and noise performance in isolated-gate InAs/AlSb high electron mobility transistors

Detection of oxygen vacancy defect states in oxide nanobelts by using thermally stimulated current spectroscopy

On the origin of blue emission from ZnO quantum dots synthesized by a sol–gel routeMore

Latest research from Journal of Atmospheric and Terrestrial Physics
Journal of Atmospheric and Terrestrial Physics
Variability in tropopause height and its temperature on different time scales: An observational study over Banqiao, Taiwan

Influence of electronically excited N2 and O2 on vibrational kinetics of these molecules in the lower thermosphere and mesosphere during auroral electron precipitation

Analyses of the effects of several earthquakes on the sub-ionospheric VLF–LF signal propagation

Does the sun work as a nuclear fusion amplifier of planetary tidal forcing? A proposal for a physical mechanism based on the mass-luminosity relation

Power spectral characteristics of ESF irregularities during magnetically quiet and disturbed days More