Events at Physics
Events During the Week of October 8th through October 15th, 2017
- Graduate Introductory Seminar
- High Energy Physics, Nuclear Physics, and Theoretical Cosmology
- Time: 12:00 pm
- Place: 4274 Chamberlin Hall
- Speaker: Carlsmith, Dasu, Herndon, Palladino, Pan, Smith, Wu, Bai, Balantekin, Barger, Chung, Everett, Hashim
- Plasma Physics (Physics/ECE/NE 922) Seminar
- Taming the plasma-material interface in plasma-burning nuclear fusion reactors
- Time: 12:00 pm
- Place: Chamberlin 2241
- Speaker: Prof. Jean Paul Allain, University of Illinois at Urbana-Champaign
- Abstract: Although progress has been made in the last half-decade in establishing an understanding of plasma-material interactions (PMI), there remain critical knowledge gaps, particularly predicting the behavior at the plasma-material interface under reactor-relevant fusion plasma conditions in a future plasma-burning neutron-dominated environment. At this interface, high particle and heat flux from the fusion plasma can limit the material’s lifetime and reliability and therefore hinder operation of the fusion device. This region is critical to operation of a nuclear fusion reactor since material can be emitted both atomistically (e.g. through evaporation, sputtering, etc.) and/or macroscopically (i.e. during transients events, such as disruptions or edge localized modes). The environmental conditions at the plasma-material interface of a future nuclear fusion reactor interacting will be extreme. The incident plasma will carry heat fluxes of the order of 100’s of MWm-2 and particle fluxes that can average 1024 m-2s-1. The fusion reactor wall would need to operate at high temperatures near 800 C and the incident energy of particles will vary from a few eV ions to MeV neutrons. Another challenge is the management of damage over the course of time. Operating at reactor-relevant conditions means the wall material would need to perform over the course of not just seconds or minutes (i.e. as in most advanced fusion devices today and in the near-future), but from months to years. Some promising breakthrough concepts have been considered such as liquid walls and low-recycling regimes that may address both radiation damage and the impact on the interaction with the plasma edge and ultimately plasma core. This talk will focus on outlining both the challenges and promises of PMI research in nuclear fusion today and the prospects for possible solutions for future plasma-burning fusion reactors. The talk will in part summarize the recent DOE Fusion Energy Sciences Workshop on Plasma-Material Interactions and also highlight some of the recent work in Prof. Allain’s RSSEL group at UIUC.
- Host: Cary Forest
- Chaos & Complex Systems Seminar
- Understanding complexities of human development in terms of space, time, and energy realities Part 1: Growing up and growing old
- Time: 12:05 pm
- Place: 4274 Chamberlin (refreshments will be served)
- Speaker: Bernard Z. Friedlander, Department of Psychology, University of Hartford (emeritus)
- Abstract: These presentations ask three questions:
Are there fundamental principles in physical science that can be useful in helping us comprehend fundamental concepts in the organization of human behavior?<br>
Can these principles help us answer the constant question–How do people get the way we are?
Does this approach, in the light of current laboratory research findings, help us clarify persistent scientific and philosophical issues in Western thought?
The two-presentation series touches upon basic concepts in these four areas of serious study: human development, basic physical science, industrial manufacturing technology, and the fine arts.
- Host: Clint Sprott
- No events scheduled
- R. G. Herb Condensed Matter Seminar
- All-Dielectric Optical Metamaterials
- Time: 10:00 am
- Place: 5310 Chamberlin Hall
- Speaker: Jason Valentine , Vanderbilt University
Optical metamaterials are man-made materials in which structuring is used to control the effective optical properties. Using the engineering freedom associated with structuring, researchers have utilized metamaterials for a number of exotic applications including sub-diffraction limit imaging and cloaking. However, absorption loss has been a major impediment to the adoption of metamaterials in practical applications. This absorption loss arises due to ohmic damping in the metals that traditionally comprise the unit cell. In this talk, I will discuss all-dielectric metamaterials in which metal, and the accompanying absorption, is completely avoided. As with their metallic counterparts, manipulation of the unit cell structure of all-dielectric metamaterials offers a means to engineer a wide variety of optical properties. Along these lines, I will discuss several implementations of all-dielectric metasurfaces with functionalities that include polarization control, wavefront tailoring, near-unity reflection, and sharp Fano resonances. The freedom to achieve a wide variety of optical properties, combined with the reduction in absorption loss, could lead to ultra-thin optical elements including lenses, waveplates and sensors as well as more complex assemblies of these elements in the form of metaoptics.
- Host: Brar
- NPAC (Nuclear/Particle/Astro/Cosmo) Forum
- Neutrino Quantum Kinetics and the Early Universe
- Time: 2:30 pm
- Place: 5280 Chamberlin Hall
- Speaker: Evan Grohs , University of Michigan
- Abstract: The laboratory of the early universe provides a setting for testing Beyond Standard Model (BSM) physics in the particle and cosmological sectors. Any BSM physics in operation at early times may produce slight deviations on the primordial element abundances and cosmic microwave background observables predicted within the standard cosmology. The identification and characterization of such BSM signatures require a precise treatment of the neutrino energy and flavor wave functions during the time of Big Bang Nucleosynthesis (BBN) using the Quantum Kinetic Equations (QKEs). I will review some of the work done on characterizing BBN with a Boltzmann-energy-transport approach, as well as ongoing work towards a full QKE treatment with neutrino oscillations and collisions. A QKE treatment of early-universe neutrino physics will greatly assist observers and theorists as the next generation cosmological experiments come on line in the near future.
- Host: Baha Balantekin
- Astronomy Colloquium
- "Observing gas in the circumgalactic medium and the Cosmic Web"
- Time: 3:30 pm
- Place: 4421 Sterling Hall, Coffee and Cookies 3:30 PM. Talk begins at 3:45 PM
- Speaker: Bart Wakker, UW Madison Astronomy Dept
- Abstract: Using HST spectra of AGN we study the gas inside and outside galaxy halos. We find that galaxies have extended (300 kpc radius) halos, which blend into the general intergalactic medium. We study properties of the gas as function of location in the galaxy halos. We also have constructed the first 3-D view of a 30x6 Mpc filament at cz~3500 km/s, This filamentis defined using a new catalogue of nearby galaxies, which is mostly complete down to a luminosity of about 0.05 L* and includes homogenized diameters and luminosities. The baryonic mass of the filament galaxies is 1.4x10^13 Msun, while the mass of filament gas outside galaxy halos is found to be 5.2x10^13 Msun. We find that simulations overpredict the detection rate of gas in the filament between 2.1 and 5 Mpc from the axis. The width of the Lya lines correlates with filament impact parameter and four BLAs in our sample all occur within 400 kpc of the filament axis, indicating increased temperature and/or turbulence. We further find that the recent Haardt & Madau (2012) extragalactic ionizing background predicts a factor 3-5 too few ionizing photons.
- Host: Astronomy Department
- R. G. Herb Condensed Matter Seminar
- *** SPECIAL TIME ***
- Revealing Interactions in Complex Systems with Coherent Multi-Dimensional Spectroscopy
- Time: 11:00 am
- Place: 5310 Chamberlin Hall
- Speaker: Jeffrey Davis, Swinburne University of Technology-Melbourne Australia
- Abstract: Multidimensional coherent spectroscopies are designed to identify and quantify interactions between quasi-particles. The nature of these interactions can vary from simple population transfer or coherent coupling, through to more complex higher-order correlations and many-body effects. The challenge with these measurements is being able to extract the salient information. We have developed methods that selectively probe specific quantum pathways, which allows us to access details of weak interactions that are otherwise hidden in complex systems. In this seminar, I will discuss some of the insights we have been able to gain in a range of sample systems, from photosynthetic light-harvesting complexes, through to coupled semiconductor nanostructures, and high-Tc cuprate superconductors.
- Host: Deniz Yavuz