Events at Physics |
Events on Monday, October 12th, 2009
- Plasma Physics (Physics/ECE/NE 922) Seminar
- Laboratory Simulations of Astrophysical Jets and Solar Coronal Loops
- Time: 12:05 pm
- Place: 4274 Chamberlin Hall
- Speaker: Paul Bellan, Cal Tech
- R. G. Herb Condensed Matter Seminar
- Special Date and Time
- Weak compressibility of surface wave turbulence
- Time: 2:30 pm
- Place: 5310 Chamberlin
- Speaker: Marija Vucelja, Weizmann Institute of Science
- Abstract: Clustering of matter on the surface of lakes and pools and of oil slicks and seaweed on the sea surface is well-known empirically but there is no theory that describes it. Since surface flows are always compressible, such a theory should be based on the description of the development of density of inhomogeneities in a compressible flow. We studied the growth of small-scale inhomogeneities in the density of particles floating in weakly nonlinear small-amplitude surface waves. Despite the small amplitude, the accumulated effect of the long-time evolution may produce a strongly inhomogeneous distribution of the floaters: density fluctuations grow exponentially with a small but finite exponent. We have shown that the exponent is of sixth or higher order in wave amplitude. As a result, the inhomogeneities do not form within typical time scales of the natural environment. Thus the turbulence of surface waves is weakly compressible and alone it cannot be a realistic mechanism of the clustering of matter on liquid surfaces. However if besides waves there are also currents, the interplay of waves with currents, might be in some cases responsible for the patchiness of the floaters.
- Host: Susan Coppersmith
- High Energy Seminar
- MiniBooNE Oscillation Results and the Sterile Neutrino Mystery
- Time: 4:00 pm - 5:00 pm
- Place: 4274 Chamberlin
- Speaker: Georgia Karagiorgi, Massachusetts Institute of Technology
- Abstract: MiniBooNE is a short-baseline experiment located at Fermilab, sensitive to muon
(anti)neutrino to electron (anti)neutrino appearance and muon (anti)neutrino
disappearance oscillations at high $Delta m^2sim$ 1 eV$^2$. These oscillation
searches have been motivated by the 3.8$sigma$ excess of electron antineutrino
events in a muon antineutrino beam observed by the LSND experiment in 1995. In
this talk, recent antineutrino and updated neutrino oscillation results from
MiniBooNE will be presented, and implications for the LSND excess will be
discussed within the context of sterile neutrino oscillation models.
- Host: Matthew Herndon