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Fall 2006 Physics Colloquium ScheduleUnless otherwise noted, the physics colloquia are held in Room 307 of the Science and Engineering Research Facility. Refreshments are served at 3:00 p.m. with the talk following at 3:30. Abstracts are included below the schedule. The ORNL Physics Division Seminar Schedule might also be of interest. Professor John Quinn is chair of the colloquium program. He may be contacted via e-mail at: jjquinn@utk.edu.
Tom Kephardt, Vanderbilt University In 1930 Dirac made a theoretically compelling argument that there should be particles with magnetic charge. Interest in magnetic monopoles has continued to this day, but these objects have yet to be discovered. We discuss how magnetic monopoles can be accommodated by modern theories of elementary particle physics, and review some of the ongoing laboratory and astrophysical searches for monopoles. Maury Goodman, Argonne National Laboratory Hong Guo, McGill University One of the important branches of nanotechnology research is the nano-scale
electronics. Nanoelectronic devices operate by the principle of quantum
mechanics, their properties are closely related to their atomic structure.
It has been a theoretical challenge to calculate device characteristics
including relevant microscopic details, especially when one wishes to
predict these characteristics without using any phenomenological parameter. David Schultz, Physics Division, ORNL and UT Department of Physics
and Astronomy Contemporary ultrafast, ultra-intense lasers are sources of huge numbers of relatively low energy photons emitted over extraordinarily short time periods. Exploiting these unique properties, laser light can be scattered in certain media to produce useful x-rays or even rare nuclear species. Because laser systems with the required characteristics are now relatively inexpensive and because the techniques used to convert the low energy photons to x-rays or radioactive ions are rapidly advancing, compact, low-cost tools for research and applications are becoming available based on these technologies. For example, small, laboratory-scale x-ray sources with characteristics approaching those of large, synchrotron-based light sources are becoming available for research in material, chemical, and biological sciences. Similarly, practical sources of radioactive ions for nuclear physics research, or for medical treatment or diagnostics, based on lasers, are now on the horizon. The present talk will introduce fundamental aspects of ultrafast, ultra-intense lasers and describe some ongoing work to develop x-ray and radioactive ion sources that use them. Harold Lee Dodds, Head of the UT Department of Nuclear Engineering Professor Dodds will provide a brief summary of the history of nuclear power development in the U.S. and elsewhere. He will also overview current activities that contribute to the "nuclear power renaissance" that is beginning to occur globally, and he will conclude with a few remarks about global climate change, renewable energy, and the diversity of energy resources. During the Q&A period after his presentation, he will gladly answer questions from the audience on reactor accidents such as Three Mile Island and Chernobyl, and on nuclear wastes. Edward Gerjuoy, University of Pittsburgh Quantum mechanics, as formulated more than 80 years ago by Schrodinger, Heisenberg, Dirac and other greats, is a wholly sufficient foundation for its modern interrelated subfields of quantum computation (qc) and quantum information (qi), which generally are lumped together into a single subfield (qc/qi). In short qc/qi, though it has been exciting the attention of a very rapidly increasing number of physicists, involves no genuinely new physics. On the other hand some of the important features and implications of quantum mechanics had been only barely appreciated before the advent of qc/qi researches, about 25 years ago. The first part of this talk will largely will concentrate on one such feature (entanglement) and one such implication (the so-called no cloning theorem), which for unfathomable reasons still receive little or no attention in modern quantum mechanics texts. Our discussion of entanglement will serve as a useful introduction to qc and its concepts, e.g., the qubit. The talk then will proceed to, and close with, a presentation (as detailed as time permits) of the Shor factoring algorithm, which provides the best known illustration of the potential power of qc. The entire talk should be quite comprehensible to any graduate student who has taken an introductory course in quantum mechanics, even if only at the undergraduate level. Victor Barzykin, UT Department of Physics and Astronomy Recent discovery of PuCoGa5, a d-wave heavy fermion superconductor with Tc=18.5K, and the measurements of NMR T1 relaxation rate and Knight shift on this and other "115" family materials (Tc ~ 1-2K) reveal striking similarities with high-Tc cuprates, suggesting that the two families of materials share a common mechanism of superconductivity. The "115" materials are a lot less complex and much cleaner than high-temperature superconductors, so we can understand what's going on in the normal and superconducting state using the two-fluid phenomenology, and it's rigorous microscopic explanation starting from the slave boson theory of Kondo lattices. It turns out, a similar two-fluid phenomenology can be developed for the pseudogap state in cuprate superconductors. The results of this phenomenological approach and the most recent Knight shift experiments indicate a breakdown of the Zhang-Rice singlet picture, the main justification for using a one-component theoretical model, the t-J model or 1-band Hubbard model, to describe these materials. Thus, one must conclude that the microscopic model for high-temperature superconductors is essentially the same as in the heavy fermion materials, with additional complex features that appear due to a strong coupling to the lattice. Stephen B. Libby, V Division, Physics and Advanced Technologies,
Lawrence Livermore National Laboratory/University of California High Energy Density Physics may be loosely defined as the study and application of matter and energy above one megabar in pressure - roughly 1 eV/particle at solid density. This regime is characterized by strong ionization, the ubiquity of shocks, fast hydrodynamic instabilities, and the importance of radiation transport in the energy balance of the medium. Beyond normal terrestrial experience until recently, the high energy density regime is now the subject of concerted laser and pulsed power driven experimentation. Applications include inertial confinement fusion (ICF) and short wavelength lasers. High energy density physics research has also contributed significantly to astrophysics. Examples range from the broad applications of radiation hydrodynamics, to the detailed microscopic models of the opacity and equation of state of hot dense matter that are a key part of the "standard solar model." In this colloquium, I will discuss the development of high energy density physics and some of its unique achievements and challenges. Hendrik Schatz, National Superconducting Cyclotron Laboratory,
Michigan State University Accreting neutron stars are bright X-ray sources that can be observed with X-ray satellites. In recent years a wide range of new phenomena has been discovered that are associated with nuclear processes on the surface and in the crust of the neutron stars. The nuclei involved are very exotic, ranging from extremely neutron deficient to extremely neutron rich. We have only begun to study some of the relevant nuclear properties experimentally using rare isotope facilities. I will discuss recent developments in observations, astrophysical modeling, and nuclear physics that together have led to a new understanding of accreting neutron stars and make them fascinating laboratories for physics under extreme conditions. Alexander Dolgov, ITEP/Moscow and INFN, Ferrara and University
of Ferrara Astronomical data accumulated during the last two decades revealed several mysterious phenomena which certainly prove that there exists new physics beyond the well established standard model. These phenomena and their possible explanations are reviewed. Main emphasis is made to the so cold dark energy which creates cosmological antigravity. Its relation to the unsolved and striking problem of vacuum energy is discussed. Previous Physics Department Colloquia: |
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