Waves & Packets
Jan. 19, 2013

Table-top Ti:sapphire laser proton accelerator could make proton therapy more accessible
Physics World
A table-top proton accelerator for medical therapy could be one step closer thanks to work done by physicists in Germany. The team's system is based on a compact Ti:sapphire laser that fires 30 fs pulses light pulses with 0.4 J energy focused on a 3 μm spot, yielding a peak intensity of 8 × 1019 W/cm2. As detailed in Applied Physics Letters, firing the laser on a diamond-like foil produces bunches of protons with energies of around 5 MeV. The team has shown that its device delivers radiation doses to biological cells that are similar to doses created by much larger conventional proton-therapy systems. The technique can also be used as a basic science tool to study ultrafast processes in materials, chemistry and biology.More

New lattice QCD method yields accessible description of neutron star interiors
Friedrich Schiller University of Jena
Physicists in Germany have introduced a new lattice QCD simulation method for dense nuclear material that, when applied to neutron stars, does not result in the star collapsing far too much in size, and also preserves typical neutron star characteristics. The new method, reported as a rapid communication in Physical Review D, depends on an approximation of the nuclear forces where the gauge group SU(3) of QCD is replaced by the exceptional group G2. This results in a non-Abelian gauge theory with fermionic baryons, and opens new avenues for high density studies of the strong force from first-principles calculations. This method does not yet give quantitatively reliable results, but it does give qualitatively real results that are computational accessible.More

Quantitative magneto-mechanical probe made possible by the Barkhausen Effect
R & D Magazine
A team of scientists in Canada have harnessed the Barkhausen Effect as a new kind of high-resolution microscopy for magnetic materials. The Barkhausen Effect is exhibited by small discontinuous jumps in magnetization vs magnetic field curves. The effect is caused by cooperative and exchange interactions of individual spins that add up to make magnetic domain structures. The amount of noise can be related to the amount of impurities or other mechanical defects in the material, and thus this effect is used as a non-destructive testing tool. In this new research, reported in Science, the team probed a specially designed magnetic structure in a thin film. The magnetization curve yields a picture of local energetics in the film, and the researchers were able to demonstrate the efficacy of the probe by focused ion-beam implantation of impurities. More

Magnetic refocusing of neutron beams should boost precision experiments and fundamental physics
RIKEN
To achieve the highest sensitivity in neutron-based experiments, researchers aim to produce very dense neutron beams. But the neutron density of the beams decreases at the beam moves from source to target. Addressing this issue, an international research team has demonstrated a method for refocusing a neutron beam that has lost its initial density. Neutrons of course cannot be controlled by electric fields, but they can by magnetic fields. So the team used a magnetic field to decelerate the fast neutrons such that the slow neutrons catch up, returning the beam to the original source density. This new method, described in detail in Physical Review A, will help in experiments to search for the neutron's so-called electric dipole moment, which in turn could provide a clue about the origin of matter in the Universe. More

Nobel Laureate's theory proven as turbid-media light propagation is directly imaged
Laser Focus World
Physicists have experimentally proven the localization theory proposed by Philip Anderson in 1958 that waves do not spread in a disordered medium if there is less than one wavelength between two defects. Anderson localization is a general phenomenon that occurs in all types of waves undergoing heavy scattering. The main challenge in using light lies in the distinction between the effects of absorption and localization. In the current work, reported in Nature Photonics, researchers overcame this challenge by measuring the time dependence of the transverse width of transmission from the turbid mixture. This allowed them to demonstrate the absorption-independent localization of light directly by imaging. More

Increase your options for graduate or REU program admissions
NSBP
The NSBP GradApps and REUApps services are open to all students and allows them to upload all the elements of an admissions application, including academic and work history, transcripts, letters of recommendation and a personal statement. Graduate and REU programs can subscribe to these databases to increase the programs' applicant pool, while at the same time allowing students can put their credentials in front of more programs than to which they would otherwise apply. More

High school astronomy teacher wins Hubble image processing competition
Hubble European Space Agency
An astronomy teacher at Pomfret School in Connecticut, USA, won first prize in the Hubble's Hidden Treasures image processing competition. The competition invited members of the public to dig out unreleased scientific data from Hubble's vast archive, and to process them into stunning images. Lake's image is of a particularly bright region of the Large Magellanic Cloud, which is located some 200,000 light-years from Earth. The gas within it slowly collapses to form new stars. In turn, the stars light up the gas clouds. In this particular winning image shows both star forming regions as well as dusty, planet-forming regions made of material from stars that have died. The Hubble archive remains open, and the outreach team invites others to search it for more hidden treasures. More

The physics of rough roads
American Physical Society
Repeated vehicle passages cause corrugated patterns in train rails and unpaved roadways owing deformations and granular flow. In Physical Review E, a team of physicists report on their combination of measurements and modeling that reveal the critical velocity for onset of the ripple as well as the ripple wave number with the largest growth rate. Dragging a metal plow blade across a flat sand bed turns out to be a good model system for vehicles driving across a road. When the plow is free to move vertically, its dynamics is simply governed by the lift force acting it. Over a uniformly flat bed the lift force is dependent on the mass plowed by the blade and is independent of its velocity. But in this work the researchers extended the analysis to cases where the bed is not uniformly flat. In this case it turns out that above a critical velocity, which depends on the mass of the plow, the blade motion becomes unstable. The findings could point to ways to mitigate the formation and damage caused by ripples in rails and roadways. More

The curious math and physics of domino chain reactions
The Physics arXiv Blog
VideoBrief A toppling domino can push over a larger domino but how much bigger can the next one be? The basic physics is straightforward. Standing a domino on its end stores a certain amount of potential energy which is released by pushing it over. However, the force required to topple the domino is smaller than the force it generates when it falls. It is this "force amplification" that can be used to topple bigger dominoes. But the devil is in the detail since there are various ways that the dominoes lose energy as they topple. Nevertheless, as shown in this video and detailed in this paper, even a growth factor of 1.5 leads to some extraordinary chain reactions. It turns out that under this analysis it does not take a particularly long series before the largest dominoes are the size of sky scrapers. More

Physicists create SQUID-like Bose-Einstein condensate
Physics World
Physicists in the US have developed an analogue of a superconducting quantum interference device (SQUID) that replaces the superconductor with a Bose–Einstein condensate (BEC) and measures rotation rather than magnetic flux. When the superconductor in looped configuration of a SQUID is replaced with a superfluid BEC, quantized angular momentum becomes the analogue of quantized current of a SQUID. In this work the team confined the BEC to a torus, but cut the torus using another laser. This cut corresponds to a Josephson junction in a SQUID. The rotating the torus-cutting laser can tune the relative flow direction of atoms in the BEC loop. The result, as described in Physical Review Letters, is a very sensitive a quantum gyroscope. But in the midst of this research the team noticed very curious BEC behavior that is not yet explained. Apparently when the BEC is stirred to quickly its superfluidity breaks down, and physicists will have to sort through several competing theories, e.g., topological excitation formation, to explain this phenomena.More

Smashing the quantum limit could mean better fiber-optic communications
National Institute of Standards and Technology
Scientists working at the NIST/Maryland Joint Quantum Institute have potentially found a way to overcome a longstanding barrier to cleaner signals in optical fibers. The result could reduce both the power needed to send a signal and the number of errors the receiver makes. Digital information is encoded in the phases of light waves. But overlaps in phases at the receiver lead to information decoding errors. Increasing the optical power is one way to overcome the error, but the so-called 'standard quantum limit' has proven to be tough challenge to beat. But by staging receivers that make successive partial measurements of the phase state, and adapt between each measurement, the overall error is reduced by a factor of four. This work is reported in Nature Photonics. More

National Society of Black Physicists jobs board postings
NSBP
Carl Albert Rouse Research Fellowship for Undergraduates
Victor M. Blanco Fellowship Research Fellowship for Undergraduates
LIGO Summer Undergraduate Research Fellowship (SURF)
Visiting Assistant Professor of Physics
WIPAC Director
Intern
Tenure-Track Faculty Position in Experimental Plasma Physics
Undergraduate Research Assistantship
NanoJapan: International Research Experience for Undergraduates
Research Experiences for Undergraduates: Materials Physics at the University of Florida
Astronomy/Astrophysics Grad Student Summer Researcher at National Solar Observatory in India
Summer Research Student
NASA Postdoctoral Fellowships
Faculty Position in Astrophysical Dynamics
REU summer program on complex materials
Assistant Professor of Physics-Tenure Track Bates College
REU Student
Two-Year Visiting Assistant Professor of Physics
National Radio Astronomy Observatory Research Experience for Undergraduates
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Latest research from New Journal of Physics
IOP Publishing
A multiphase model for three-dimensional tumor growth

Experimental detection of quantum information sharing and its quantification in quantum spin systems

The relationship between structure and function in locally observed complex networks

Alternans by non-monotonic conduction velocity restitution, bistability and memory

Third-order spatial correlations for ultracold atoms

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Latest Research from Journal of the Optical Society of America B
Optical Society of America
Negative refraction in causal media by evaluating polar paths for rational functions

Nonlinear imaging properties under the coeffect of two wirelike opaque scatterers

Highly efficient optical Fredkin gate with weak nonlinearities and classical information feed-forward

Efficient generation of hyperentangled photon pairs with controllable waveforms from cold atoms

Analysis of effective plasma frequency in a superconducting photonic crystal

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