Events at Physics
Events on Thursday, April 15th, 2010
- R. G. Herb Condensed Matter Seminar
- Quantum Critical Behavior in Cuprate Superconductors
- Time: 10:00 am
- Place: 5310 Chamberlin
- Speaker: Tom Lemberger, The Ohio State University
- Abstract: On the basis of measurements of superfluid density NS and transition temperatures Tc, we argue that the physics of underdoped cuprates is dominated by fluctuations associated with a quantum superconductor-to-insulator phase transition. "Thick" films exhibit 3D scaling of Tc with NS, while ultrathin films two unit cells thick exhibit the expected 2D scaling. Observation of 3D fluctuations contradicts the well-known "Uemura relation" which holds that thick samples have 2D fluctuations. On the other side of the cuprate phase diagram, recent results on overdoped La2-xSrxCuO4 films show that these films suddenly become amazingly homogeneous, possibly due to another quantum phase transition. We'll speculate on what might be going on there.
- Host: Robert Joynt
- NPAC (Nuclear/Particle/Astro/Cosmo) Forum
- DeepCore - Extending the physics reach of the IceCube Neutrino Observatory
- Time: 4:00 pm - 5:00 pm
- Place: 4274 Chamberlin
- Speaker: Darren Grant, University of Alberta
- Abstract: IceCube's DeepCore is a compact Cherenkov detector located at the bottom-centre of the neutrino observatory. It's purpose is to enhance the sensitivity of IceCube to low neutrino energies (< ~300GeV) and lower the detection threshold of the observatory by an order of magnitude to ~10 GeV. The improved sensitivity in this low-energy window enhances the ability of the observatory to perform dark matter searches via the products of WIMP annihilations, and thus probe an extensive range of the allowable SUSY parameter space for spin-dependent interactions. It also opens new possibilities for atmospheric neutrino oscillation measurements, muon neutrino disappearance and tau neutrino appearance, in an energy region not well tested by previous experiments. Finally, utilizing the IceCube array as an active veto, DeepCore enlarges the field of view of the observatory to the full sky when searching for potential neutrino sources. In this talk I will discuss the current status of the detector, fully deployed as of January 2010, and the development of the DeepCore analyses.
- Host: Albrecht Karle