Events at Physics |
Events During the Week of November 8th through November 14th, 2009
Monday, November 9th, 2009
- Plasma Physics (Physics/ECE/NE 922) Seminar
- Lithium Experiments on the T-11M Tokamak: Development of Plasma Facing Components for a Steady-State fusion Reactor
- Time: 12:05 pm
- Place: 2301 Sterling
- Speaker: Sergei Mirnov, TRINITI Laboratory, Troitsk, Russia
- NPAC (Nuclear/Particle/Astro/Cosmo) Forum
- The first year of the Fermi Large Area Telescope in space
- Time: 2:00 pm
- Place: 5310 Chamberlin Hall
- Speaker: Markus Ackermann
- Abstract: Astrophysical results obtained by the Fermi Large Area telescope
mission in the first year of its mission are presented. In its first year the LAT has detected more than 10 million gamma-rays above 100 MeV and more than 1000 point sources, many of which were studied individually. These studies cover a wide range of astrophysical objects, like AGN, GRB, Starburst Galaxies, Pulsars, their Nebulae and Supernova Remnants. Besides individual objects, the properties of the diffuse emission from our own galaxy and beyond have been analyzed, yielding
new insights into the propagation of cosmic rays and the nature of the extragalactic diffuse emission. - Host: Albrecht Karle
- High Energy Seminar
- Search for active neutrino disappearance in MINOSSearch for active neutrino disappearance in MINOS
- Time: 4:00 pm
- Place: 5310 Chamberlin
- Speaker: Brian Rebel, FNAL
- Abstract: MINOS is a long baseline neutrino oscillation experiment with two detectors<br>
separated by a distance of 735 km. The detectors are exposed to a high<br>
power muon neutrino beam originating at Fermilab. It has reported a<br>
significant deficit of muon neutrinos at its far detector relative to the<br>
near detector through measurement of the rate of charged-current<br>
interactions. If this deficit is due solely to conversions of muon-neutrinos<br>
to electron- and tau-neutrinos, then the rate of neutral-current (NC)<br>
interactions at the far detector remains unchanged from the non-oscillation<br>
prediction. Alternatively, if any muon-neutrinos convert to a sterile<br>
state, then the NC rate would be suppressed and the reconstructed energy<br>
spectrum would be distorted. In this talk I will describe the analysis of<br>
the NC interactions from an exposure of the MINOS detectors to 3.2 x 10^20<br>
protons on target. - Host: Matthew Herndon
Tuesday, November 10th, 2009
- Chaos & Complex Systems Seminar
- The stability of oscillators
- Time: 12:05 pm
- Place: 5310 Chamberlin (Refreshments will be served)
- Speaker: George Hrabovsky, Madison Area Science and Technology
- Abstract: By converting an oscillator equation to a well-known special function equation, it is possible to apply a graphical method of analysis to determine if an oscillation is stable, and to locate where solutions become unphysical when it is not stable.
- Astronomy Colloquium
- What sets the Maximum Spin Rate of Neutron Stars?
- Time: 3:30 pm - 5:00 pm
- Place: 3425 Sterling Hall
- Speaker: Ira Wasserman, Cornell University, Astronomy Department
- Abstract: The fastest rotating neutron star has a spin frequency of 716 Hz, well below the maximum allowed by stability in general. The accepted view is that fast spin results from accretion, but the R mode instability of a rotating neutron star seems to prevent spin up to frequencies as high as the fastest observed. What is going on?
- Host: Professor Ellen Zweibel
Wednesday, November 11th, 2009
- No events scheduled
Thursday, November 12th, 2009
- R. G. Herb Condensed Matter Seminar
- Oxide Nanoelectronics
- Time: 10:00 am
- Place: 5310 Chamberlin
- Speaker: Jeremy Levy, University of Pittsburgh
- Abstract: Electronic confinement at nanoscale dimensions remains a central means of science and technology. In this talk, I will describe a new method for producing extreme nanoscale electronic confinement at the interface between two separately insulating oxides, LaAlO3 and SrTiO3. Using an approach reminiscent of the popular toy "Etch-a-Sketch", we scan an electrically biased probe on the surface of this heterostructure to create nanoscale conducting islands, nanowires, tunnel junctions and field-effect transistors at the interface. The smallest feature size approaches one nanometer. These structures are created in ambient conditions at room temperature, and can be erased and rewritten repeatedly. At low temperatures, a variety of quantum phases have been observed, including integer and fractional quantum Hall states and superconductivity. This new, on-demand nanoelectronics platform has the potential for widespread scientific and technological exploitation.
This work is supported by the National Science Foundation, Defense Advanced Research Projects Agency, Army Research Office and Air Force Office of Scientific Research. - Host: Mark Rzchowski
- NPAC (Nuclear/Particle/Astro/Cosmo) Forum
- Galactic cosmic ray anisotropy : origin and implications and the role of IceCube
- Time: 4:00 pm
- Place: 5310 Chamberlin
- Speaker: Paolo Desiati, University of Wisconsin at Madison
- Abstract: The assumed isotropy of galactic cosmic rays has been topic of investigation since the seventies, when an O(10^-3 - 10^-4) anisotropy in arrival direction has been observed for the first time. The wide energy range of this observations (from tens of GeV to hundreds of TeV) has raised questions on the origin of this phenomenon. While we can generically claim that the responsible of this anisotropy is to be connected to the structure of the Local Interstellar Medium, and specifically to the Local Interstellar Magnetic Field (within about 0.1-1.0 pc ~ 20,000 - 200,000 AU), we still suffer from the lack of knowledge of the properties of our local environment. Only recently, with the observation of O(10-30 degrees) excess of cosmic rays by MILAGRO and with the first high statistics observation of the southern sky by IceCube, the topic is gaining renewed attention. The possibility that the ~100's TeV galactic cosmic ray anisotropy might be connected to the blast from a nearby supernova, in connection with the anomalies in the observed positron fraction and electron spectrum is very appealing and will be discussed.
- Host: Michael Ramsey-Musolf
- Introductory Graduate Seminar
- Phenomenology
- Time: 5:30 pm
- Place: 2223 Chamberlin Hall
- Speaker: Barger, Everett, Halzen, Han, Petriello, University of Wisconsin Department of Physics
Friday, November 13th, 2009
- NPAC (Nuclear/Particle/Astro/Cosmo) Forum
- Lepton) Flavor Violation in SUSY GUT and Randall-Sundrum Models
- Time: 2:30 pm
- Place: 2301 Sterling Hall
- Speaker: Mu-Chun Chen, U. C. Irvine
- Abstract: In the first part of this talk, I will discuss theoretical predictions of various SUSY GUT models for lepton flavor violation. Including the WMAP dark matter constraints, lower bounds on the branch fractions of these LFV rare charged lepton decays can be obtained. Furthermore, a next generation MECO-like experiment turns out to be the more robust way in distinguishing various GUT models.<br>
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In the second part of the talk, I will focus on flavor violation in RS models. Generically, RS models suffer from strong constraints due to the presence of the FCNCs at tree-level. Furthermore, these models require fine tuning in order to get large neutrino mixing. I will present a model based on the double tetrahedral family symmetry which successfully avoids the tree-level FCNCs in both quark and lepton sectors. In addition, our model gives rise to realistic masses and mixing angles for both quarks and leptons. - Host: Michael Ramsey-Musolf
- Physics Department Colloquium
- Inward Turbulent Diffusion of Plasmas in a Levitated Dipole
- Time: 4:00 pm
- Place: 2241 Chamberlin Hall (coffee at 3:30 pm)
- Speaker: Michael Mauel, Columbia University
- Abstract: The rearrangement of plasma due to turbulence is among the most important processes that occur in planetary magnetospheres and in experiments used for fusion energy research. Remarkably, fluctuations that occur in active magnetospheres drive particles inward and create centrally peaked profiles. Until now, the strong peaking seen in space has been undetectable in the laboratory because the loss of particles along the magnetic field is faster than the net driven flow across the magnetic field. Here, we report the first laboratory measurements in which a strong superconducting magnet is levitated and used to confine high temperature plasma in a configuration that resembles planetary magnetospheres. Levitation eliminates field-aligned particle loss, and the central plasma density increases dramatically. The buildup of density characterizes a turbulent pinch and is found equal to the rate predicted from measured electric field fluctuations. Our observations show that dynamic principles describing magnetospheric plasma are relevant to plasma confined by a levitated dipole.
- Host: Forest