Events at Physics
Events During the Week of April 11th through April 18th, 2010
- Plasma Physics (Physics/ECE/NE 922) Seminar
- "Ideal and Non-Ideal Tokamak Edge Stability Calculations"
- Time: 12:05 pm
- Place: 2241 Chamberlin Hall
- Speaker: Nate Ferraro, General Atomics
- High Energy Seminar
- New Results for Electron-Neutrino Appearance in MINOS
- Time: 4:00 pm - 5:00 pm
- Place: 4274 Chamberlin (Coffee and Cookies at 3:45 pm)
- Speaker: Prof. Mayly Sanchez, Iowa State
- Abstract: MINOS is a long baseline neutrino oscillation experiment designed to
make precision measurements of the neutrino mixing parameters
associated with the atmospheric neutrino mass splitting. Using a
neutrino beam from the Main Injector (NuMI) facility at Fermilab, it
compares the neutrino energy spectrum for charged current muon
neutrino interactions observed in two large detectors located at
Fermilab and in the Soudan mine in northern Minnesota at a distance
of 735km. The MINOS Collaboration has? published the world?s best
measurement of the atmospheric mass scale by studying muon neutrino
disappearance. It has also studied the possibility of muon neutrinos
oscillating into sterile neutrinos. Beyond summarizing these recently
published results, I will focus on describing our new results on
electron neutrino appearance in MINOS after three years of
- Host: Herndon
- Chaos & Complex Systems Seminar
- "Shock Waves in Nature and in Numerical Computations"
- Time: 12:05 pm
- Place: 4274 Chamberlin Hall
- Speaker: James Rossmanith, UW-Madison, Dept. of Mathematics
- Abstract: Shock waves are propagating disturbances that are characterized by an abrupt, nearly discontinuous change in the characteristics of a fluid or plasma. They can occur in a variety of phenomena in both laboratory and natural settings. Mathematically, shock waves are difficult to handle since in general they are not unique solutions of the equations that model them. Computationally, shock waves are difficult to handle for several reasons: (1) most discontinuous cannot be exactly represented on a discrete mesh, (2) standard high-order methods are unstable for shocks, and (3) the numerical schemes must be carefully constructed to yield the physically correct solution.
In this talk I will begin by briefly reviewing the basic theory of shock waves. I will then, mostly through computational examples, describe the various pitfalls in trying to numerically solve equations with shock solutions. Finally, I will describe some strategies based on adaptive mesh refinement to obtain highly accurate numerical solutions.
- Astronomy Colloquium
- " Nearby, Thermally Emitting Neutron Stars"
- Time: 3:30 pm - 5:00 pm
- Place: 3425 Sterling Hall
- Speaker: David Kaplan, UW-Milwaukee
- Abstract: Neutron stars are among the densest objects in the universe. The conditions in their centers are largely unconstrained by current theoretical physics or terrestrial laboratories, leaving a wide variety of compositions and structures possible. Observations of thermal emission from neutron stars -- specifically measurements of their sizes and cooling rates -- may therefore be the best way to constrain the behavior of matter in these extreme conditions. I will discuss a sample of nearby, cooling neutron stars that we are using for this purpose. We are attempting to pin down the basic parameters of these neutron stars with a variety of ground- and space-base observations, coupled with theoretical modeling. Along the way, we have encountered a number of interesting astrophysical puzzles that I will describe.
- Host: Astro Dept
- Phenomenology Seminar
- Precise Predictions for Higgs Production at Hadron Colliders within the SM and Beyond
- Time: 11:00 am
- Place: 4272 Chamberlin Hall
- Speaker: Radja Boughezal, Institute for Theoretical Physics, University of Zürich
- Abstract: The search for the Higgs boson is a primary goal of the LHC and a top priority at the Tevatron. The Tevatron experiment has reported limits for the Higgs boson cross-section. After eight years of collecting data of proton-antiproton collisions at 2 TeV, these experiments are becoming increasingly sensitive to a potential Higgs boson signal. After a short review of the theoretical and experimental motivations for studying specific Higgs production mechanisms, we describe the theoretical framework in which predictions are calculated. We then discuss new results for Higgs boson signals at hadron colliders, taking into account contributions from Standard Model particles as well as possible new physics effects.
- 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
- Physics Department Colloquium
- Fay Ajzenberg-Selove Colloquium
- Dark Matter in the Universe
- Time: 4:00 pm
- Place: 2241 Chamberlin Hall (coffee at 3:30 pm)
- Speaker: Katherine Freese, University of Michigan
- Abstract: One of the biggest unanswered questions in science is
"What is the Universe made of?" Only 4% of the Universe consists of ordinary atomic matter; the remaining 96% is made of Dark Matter and Dark Energy whose nature is as yet unknown. This talk will examine the dark matter that
comprises most of the mass of the Milky Way and all other galaxies. I will review the observational evidence for the existence of dark matter, and then turn to the hunt for the dark matter particle. A great deal of excitement currently pervades this field because of current and upcoming experiments that can find the dark matter, via both direct and indirect techniques. The best motivated dark matter candidates are Weakly Interacting Massive Particles such as those motivated by supersymmetry or extra dimensions. These particles have been powerful motivation for the Large Hadron Collider at CERN, underground experiments (e.g; XENON, CDMS), satellites such as GLAST or PAMELA, and neutrino detectors such as ICECUBE/DEEPCORE at the South Pole. The discovery of the dark matter particle will be an exciting milestone for particle physics, astrophysics, and for everyone interested in understanding the nature of our Universe.
- Host: Chung