Physics and Astronomy Colloquium Series
Talks are scheduled for Thursdays at 12:40 PM in Room N304 of the Science and Engineering Building, unless otherwise indicated. Pizza and beverages are served at 12:20PM.
All are welcome!
Date |
Talk |
Thursday
| Senior Thesis Talks Paul Amy
|
Thursday
| Ultracold atoms in optical lattices: quantum information and solid state physics with dilute-gas Bose-Einstein condensates Nathan Lundblad
Bose-Einstein condensation burst onto the atomic physics stage 13 years ago, ushering in a new era of atomic physics and providing sources of coherent matter waves as well as a window into phenomena at the nanoKelvin scale. BECs have been put to particularly elegant use in recent experiments involving optical lattices: standing waves of laser light that confine the atoms of the BEC in a periodic array of traps in one, two, and three dimensions. The resulting system can be used as a stable and tunable analogue of crystal-lattice condensed-matter systems, allowing (for example) insight into the Mott-insulator/superfluid transition; the single-atom control also allows for the implementation of various quantum computing protocols. I will give an overview of recent experiments at NIST exploring these possibilities. |
Thursday
| The Physics of Mechanical Reinforcement in Nanofilled Polymer Melts and Elastomers S. S. Sternstein
Carbon black reinforcement of rubber for use in automobile tires has been practiced for about 100 years, but the mechanism by which reinforcement occurs remains controversial. Curiously, one of the earliest theories used to explain reinforcement is based on Einstein's well-known theory of viscosity enhancement in particulate filled liquids. This seminar will provide a broad perspective of the reinforcement issue, which include aspects of mechanics of solids and composites, materials science, polymer physics, rheology and statistical thermodynamics, making reinforcement a rich subject for multidisciplinary exploration. It will be shown experimentally that the Einstein equation fails to predict the correct limiting behavior of reinforced polymer melts as zero filler concentration is approached. Additionally, it will be argued that the reinforcement mechanism is not due primarily to filler agglomeration and/or percolation, but rather is due to the intrinsic statistical conformational behavior of polymer chains in the presence of filler particles. |
Thursday
| The Lifetime of the Neutral Pion - Results from the PrimEx Experiment Mark Ito
The lifetime of the neutral pion has a long history from both the theoretical and experimental point of view. Since there are no hadronic states lighter than the &pi0 its strong decay is not allowed. Still its short lifetime (of order 10-16 s) made direct observation of a finite decay distance impossible for 35 years after its discovery. The first theory of its decay emerged in the 1960's and concluded that it should be a stable particle. Currently, the most accurate experiment and most modern theoretical calculations are in marginal disagreement. The PrimEx experiment at Jefferson Lab uses an indirect method, the Primakoff effect, to infer the lifetime with unprecedented precision. Preliminary results from PrimEx will be presented and the experimental outlook discussed. |
Friday
| Steinmetz Symposium Union Physics and Astronomy Students present their research
|
Thursday
| Solid-State Lighting with Wide Bandgap Group III - Nitride Semiconductors Christian Wetzel
Electric lighting is a sizeable factor in the world's energy
consumption and
human environmental impact. Solid-State lighting therefore aims to replace
all incandescent and fluorescent lighting with highly efficient light
emitting diode (LED) solutions. Alloys and heterostructures of group-III
nitride semiconductors GaN, AlN, and InN can be tuned to cover the entire
visible spectrum and the near UV. Yet, while blue LEDs already have achieved
an efficiency as 60%, significantly lower values so far limit the
performance in the green spectral region.
|
Thursday
| Bringing the Excitement of Physics to the Public, or Fighting the War on Error Jessica Clark
Public Outreach helps introduce people of all ages to the wonders of physics. With this in mind, the American Physical Society develops programs that aim to increase public awareness and appreciation of how physics profoundly increases our understanding of the universe and improves the human condition. This talk will highlight the last eight years of APS Public Outreach and will offer ideas for broadening your department's impact on the local community and beyond through outreach. |
Thursday
| Block Copolymer Lithography: How to Convince Thermodynamics to Work for You Kevin Cavicchi
With the growth of nanotechnology and the shrinking of device sizes in the microelectronics industry there has been growing interest in using the thermodynamically driven self-assembly of molecules to pattern surfaces. These "bottom-up" patterning techniques offer unique advantages when compared to traditional "top-down" methods, such as optical lithography. Block copolymers have attracted considerable attention for patterning due to their ability to form ordered nanostructures on length scales of tens of nanometers. This talk will give an overview of the physics of block copolymers with a focus on how solvents can be used to control the morphology of nanostructured block copolymer thin films. |
Friday
|
Joint Colloquium with Mechanical Engineering and ChemistryCombustion synthesis of tin dioxide nanocomposites for gas sensing applications Smitesh Bakrania, '03
The current work focuses on understanding the mechanisms controlling tin dioxide (SnO2) nanoparticle morphology in combustion synthesis systems and how nanoarchitecture affects performance of solid-state gas sensors. A range of analytical methods (including transmission and scanning electron microscopy, x-ray diffraction, nitrogen absorption, and XEDS) were used to characterize the materials properties as a function of the combustion synthesis conditions. The results suggest a relationship between the precursor crystallite size and the product nanoparticles. The combustion synthesis and sensor fabrication methods that are the results of these studies will dramatically accelerate the design of new sensors and sensor optimization. Please note special date and time. Lunch will be provided starting at 12:30pm in the Olin Rotunda. |
Winter 2008 Colloquium Schedule
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Last Updated: May 6, 2008