Events at Physics |
Events During the Week of May 3rd through May 10th, 2009
Monday, May 4th, 2009
- Physics Department Lecture
- Angels & Demons of the CERN Large Hadron Collider
- Time: 7:30 pm
- Place: 2103 Chamberlin Hall
- Speaker: Wesley Smith, UW Department of Physics
- Abstract: The upcoming blockbuster movie Angels & Demons focuses on an apparent plot to destroy the Vatican using a small amount of antimatter. Parts of the movie were actually filmed in the Large Hadron Collider at the European particle physics laboratory CERN. At the University of Wisconsin Physics Department, Professor Wesley Smith will lecture on the the real science of animatter, the CERN Large Hadron collider and the excitement of particle physics research.
Tuesday, May 5th, 2009
- Chaos & Complex Systems Seminar
- Earthquakes beneath the sea: Understanding the mechanics of fault zones through subsurface imaging and scientific drilling
- Time: 12:05 pm
- Place: 4274 Chamberlin
- Speaker: Harold Tobin, UW Department of Geology and Geophysics
- Abstract: Understanding of the processes by which earthquakes occur remains one of the great challenges of geophysics. The complex interplay among frictional processes, stress, pore fluid pressure, temperature, and other factors means that a comprehensive model for fault physics has not been achieved. One reason for this is the lack of in situ observations and samples from within the faults deep beneath the earth's surface. To address this problem, several major projects have been launched to drill into fault zones. The massive subduction earthquakes which occur at the boundary between two tectonic plates at subduction zones are especially of interest because they cause devastating tsunami, and occur with repeating characteristics. Off the Pacific coast of Japan, the NanTroSEIZE (Nankai Trough Seismogenic Zone Experiment) project targets a subduction zone for drilling to sample and place instruments into and around the fault zone responsible for these tsunami-generating earthquakes. Three-dimensional seismic reflection surveys image the plate boundary zone and provide evidence for fault properties. Drilling provides evidence on the rock composition, chemistry, stress, and other parameters. These unique new datasets are helping to test theoretical and laboratory-derived models for fault physics. I will discuss the overall challenge and present results from the first phase of drilling in 2007-2008.
- Astronomy Colloquium
- The Power of Cooling Cores in Clusters in Galaxies
- Time: 3:30 pm
- Place: 6515 Sterling Hall
- Speaker: Mateusz Ruszkowski, University of Michigan
- Abstract: A significant fraction of clusters of galaxies possess cool cores. If uninhibited, the cooling of the intracluster medium (ICM) will result in extreme mass accretion rates which is contrary to observations. It is widely accepted now that active galactic nuclei (AGN), and possibly other processes, "conspire" to heat the cluster plasma and prevent such "cooling catastrophes". However, several aspects of this process are not understood. I will discuss some of the outstanding problems of the energetics of cool cores in clusters of galaxies. More specifically, I will discuss (1) the role of the brightest cluster galaxy and the mass of its central black hole in supplying the energy, (2) the impact of the energy transfer by thermal conduction, (3) the role of the magnetic fields in slowing the mixing of the hot AGN-inflated bubbles with the ICM and, finally, (4) I will briefly comment on our ongoing efforts to understand the role of anisotropic conduction in cosmological simulations of cluster formation. <br>
- Host: Professor Sebastian Heinz
Wednesday, May 6th, 2009
- R. G. Herb Condensed Matter Seminar
- Electronic, spin and transport properties of a triple quantum dot molecule
- Time: 10:00 am
- Place: 5310 Chamberlin
- Speaker: Yun-Pil Shim
- Abstract: I will present a theory of lateral triple quantum dot system in a triangular geometry. In this setting, the strong Coulomb interaction and the quantum interference effects play important roles in determining the electronic and spin properties. Configuration-interaction method is used to obtain the many-electron eigenstates and the effects of magnetic field will be explained. It will be shown that this system can be used to realize localized spins with tunable interactions by using purely electrical methods. Transport through this system will be discussed in a simple framework based on rate equations.
- Host: Mark Friesen
- Plasma Physics (Physics/ECE/NE 922) Seminar
- "Simultaneous Measurement of Electron temperature and Density Fluctuations in the Core of DIII-D Plasmas and Comparison with Nonlinear Gyrokinetic Simulations
- Time: 12:05 pm
- Place: 3345 Engineering Hall
- Speaker: Dr. Anne White, General Atomics
Thursday, May 7th, 2009
- R. G. Herb Condensed Matter Seminar
- Let there be light: from graphene oxide to dark excitons
- Time: 10:00 am
- Place: 5310 Chamberlin
- Speaker: Jay Kikkawa, University of Pennsylvania
- Abstract: TBA
- Host: Robert Joynt
- Atomic Physics Seminar-Note special time
- Schlieren measurements of Hg density gradients in an ultra-high pressure arc lamp
- Time: 12:30 pm
- Place: 5310 Chamberlin
- Speaker: Joe Kane, University of Wisconsin-Madison
- Abstract: A Brewster angle reflection measurement is used to determine the Hg vapor density at the arc tube wall of an ultra-high pressure lamp. The density measurement in combination with the wall temperature yields a pressure of 201 +/- 11 bar. This lamp pressure in combination with an arc core temperature measurement yields an arc core Hg vapor density of 1.78 x 10^20 cm^-3, which agrees with the density from resonance collisional line broadening measurements of the 1014 nm Hg line. These density results are combined with Abel inverted laser deflection or schlieren measurements to determine a density/temperature map of the Hg vapor in the lamp. The laser deflection technique is sensitive in the arc core and mantle, unlike emission techniques which are sensitive only in the arc core.
- Host: Jim Lawler
- NPAC (Nuclear/Particle/Astro/Cosmo) Forum
- High Precision Cosmology with Baryon Acoustic Oscillations
- Time: 4:00 pm
- Place: 5310 Chamberlin
- Speaker: Hee-Jong Seo, Fermilab and U. Arizona
- Abstract: Baryon acoustic oscillations (BAO) in large galaxy surveys can provide an excellent standard ruler test to measure the cosmological distance scale, such as the angular diameter distance and the Hubble parameter, and therefore dark energy properties. This requires that we understand all of the physical effects that could alter the acoustic feature during the nonlinear evolution of structure. There are two important aspects of the nonlinear effects on BAO. First, the BAO signature is gradually reduced with time and in scale due to nonlinear growth of density fields, redshift distortions, and galaxy bias. Second, the various nonlinear effects may alter the observed BAO scale at low redshift, relative to the linear acoustic scale derived from the CMB, which would result in biased estimation of dark energy parameters. In this talk, I will present effects of such nonlinearities on BAO from N-body results: nonlinear growth and redshift distortions degrade the contrast of BAO while shifting BAO less than ~0.5% at z=0.3. I will show that most of these nonlinear effects can be reversed by a simple reconstruction scheme.I will also discuss the effect of galaxy bias on BAO.
- Host: Peter Timbie
Friday, May 8th, 2009
- Last Day of Class
- Physics Department Colloquium
- Physics Department Awards Colloquium
- What life is like for a physicist in Congress
- Time: 4:00 pm
- Place: 2241 Chamberlin Hall (coffee at 3:30 pm)
- Speaker: Bill Foster, U.S. Congressman Representing the 14th District of Illinois
- Abstract: Bill Foster is a High-Energy particle physicist, Madison native and UW Physics graduate recently elected to replace former Speaker of the House Dennis Hastert in a hotly-contested special election for the U.S. Congress. Bill is the son of UW Law School Prof. George William (Bill) Foster, a civil rights lawyer and early activist in the Dane County Democratic Party. While a student at the UW, Bill and his younger brother Fred founded Electronic Theatre Controls, Inc., now the world's largest stage lighting company with headquarters in Middleton. Returning to physics grad school at Harvard, Bill's Ph.D thesis experiment was the IMB Proton Decay detector and was the co-recipient of the Rossi Prize for the discovery the neutrino burst from supernova SN1987A. Bill's career in High-Energy Physics included 22 years at Fermilab, where he helped build the CDF experiment that discovered the top quark, built high-speed integrated circuits, 100kA superconducting magnets, and particle beam damper circuits. Bill was the co-inventor and magnet designer of the Fermilab Recycler Antiproton Storage Ring, a 3.3 km antiproton storage ring used to increase the luminosity of the Fermilab Tevatron.
In 2006, Bill tragically succumbed to the familial recessive gene for adult-onset political activism. He will describe his experiences as a physicist running for office, serving in the U.S. Congress, and as a member of the Financial Services Committee. - Host: Department of Physics