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Entropy Can Lead to Order, Paving The Route to Nanostructures

By Guest PostJuly 28, 2012Scienceaerodynamics, atoms, computer simulation, crystal structure, disorder, drifting particle, entropy, michael engel, nanoparticle, pablo damasceno, particle, Science, shape, sharon glotzer, university of michigan

ANN ARBOR, Mich.— Researchers trying to herd tiny particles into useful ordered formations have found an unlikely ally: entropy, a tendency generally described as “disorder.”

Computer simulations by University of Michigan scientists and engineers show that the property can nudge particles to form organized structures. By analyzing the shapes of the particles beforehand, they can even predict what kinds of structures will form.

The findings, published in this week’s edition of Science, help lay the ground rules for making designer materials with wild capabilities such as shape-shifting skins to camouflage a vehicle or optimize its aerodynamics. (more…)

Greg Landsberg: Seeking the Higgs boson

By Guest PostJune 29, 2012Scienceamerican group, brown, CERN, cms, compact muon solenoid, data, david cutts, david orenstein, electromagnetic interaction, electroweak force, electroweak symmetry breaking, fermilab, gerald guralnik, greg landsberg, higgs, higgs boson, higgs field, higgs mechanism, higgs signal, high precision, lack of sleep, Large Hadron Collider, meenakshi narain, megapixel camera, particle, phenomenon, photon, professor of physics, skype, standard model, statistical significance, switzerland, ultich heintz, universe, z bosons

Greg Landsberg, professor of physics at Brown, is the physics coordinator for the Compact Muon Solenoid (CMS) at CERN in Switzerland, part of a Brown team that includes professors David Cutts, Ultich Heintz, and Meenakshi Narain. The giant instrument’s primary mission is finding the Higgs boson, a particle whose existence would confirm the best guess physicists have made about why things have mass.

On July 4, Landsberg and his colleagues will reveal the latest results of their search. Anything could happen when Greg Landsberg and, including an announcement that the Higgs has been found or that it has been ruled out, sending theorists back to the whiteboard. Landsberg spoke by Skype with science news officer David Orenstein on June 26 as CERN physicists were preparing for their press conference. (more…)

Images Capture Split Personality of Dense Suspensions

By Guest PostApril 9, 2012Sciencedna microarray, drop forms, heinrich jaeger, jeffrey morris, marc miskin, mathematical model, nozzle diameter, particle, phenomena, steve koppes, university of chicago, viscosity, viscous, viscous liquids, viscous mixture, zirconium dioxide

Stir lots of small particles into water, and the resulting thick mixture appears highly viscous. When this dense suspension slips through a nozzle and forms a droplet, however, its behavior momentarily reveals a decidedly non-viscous side. University of Chicago physicists recorded this surprising behavior in laboratory experiments using high-speed photography, which can capture action taking place in one hundred-thousandths of a second or less.

UChicago graduate student Marc Miskin and Heinrich Jaeger, the William J. Friedman and Alicia Townsend Friedman Professor in Physics, expected that the dense suspensions in their experiments would behave strictly like viscous liquids, which tend to flow less freely than non-viscous liquids. Viscosity certainly does matter as the particle-laden liquid begins to exit the nozzle, but not at the moment where the drop’s thinning neck breaks in two. (more…)

Anti-Helium Discovered in the Heart of STAR

By Guest PostApril 26, 2011Scienceaccelerator technology, alpha magnetic spectrometer, ams, anti heavy hydrogen, anti hypertriton, antialpha, antideuteron, antielectron, antihelium 4, antinucleons, antiparticles, antiproton, baryon, baryon number, berkeley lab, carl anderson, CERN, collisions of energetic gold nuclei, ernest rutherford, experiment, hans georg ritter, heaviest antiparticle, nu xu, nucleus, nucleus of antihelium 4, nucleus of antihydrogen, particle, positron, relativistic heavy ion collider, rhic, star, star experiment

*Berkeley Lab nuclear scientists join with their international colleagues in the latest record-breaking discovery at RHIC*

Eighteen examples of the heaviest antiparticle ever found, the nucleus of antihelium-4, have been made in the STAR experiment at RHIC, the Relativistic Heavy Ion Collider at the U.S. Department of Energy’s Brookhaven National Laboratory.

“The STAR experiment is uniquely capable of finding antihelium‑4,” says the STAR experiment’s spokesperson, Nu Xu, of the Nuclear Science Division (NSD) at Lawrence Berkeley National Laboratory (Berkeley Lab). “STAR already holds the record for massive antiparticles, last year having identified the anti-hypertriton, which contains three constituent antiparticles. With four antinucleons, antihelium-4 is produced at a rate a thousand times lower yet. To identify the 18 examples required sifting through the debris of a billion gold-gold collisions.” (more…)

Tag Archives: particle

Entropy Can Lead to Order, Paving The Route to Nanostructures

Greg Landsberg: Seeking the Higgs boson

Images Capture Split Personality of Dense Suspensions

Anti-Helium Discovered in the Heart of STAR