Bulletin of the American Physical Society
2007 New England Section of the APS and AAPT Joint Fall Meeting
Volume 52, Number 17
Friday–Saturday, October 19–20, 2007; Storrs, Connecticut
Session E3: APS Contributed Talks: General Physics |
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Chair: Barry Wells, University of Connecticut Room: MSB BSP-131 |
Saturday, October 20, 2007 8:00AM - 8:15AM |
E3.00001: Local surface structure and composition determination by low-energy electron microscopy and Monte Carlo simulation Jiebing Sun, James B. Hannon, Gary L. Kellogg, Karsten Pohl It has been long pursued to accurately measure surface structure and composition with high temporal and spatial resolutions. Modern surface analytical techniques, however, either have to assume a homogeneous surface structure, or have only a very limited sensitivity to subsurface or chemical composition. We have developed a novel analysis technique to overcome these limitations [1-2]. We are able for the first time to measure a complete 3D composition map of the first three surface layers in real time by analyzing low-energy electron microscopy imaging intensity dynamically. We have demonstrated that a lateral spatial resolution of about 8.5 nm can be achieved to unravel the origin of the heterogeneous PdCu surface alloy grown on a Cu(001) substrate. A fundamental step-overgrowth mechanism has been identified to be responsible for the heterogeneity developing around steps, a generic mechanism relevant to many thin-film systems. Furthermore, Monte Carlo simulations indicate that the favorable NN Pd-Cu bonding is responsible for the heterogeneity in the PdCu system and not a slow diffusion process. [1] J. B. Hannon \textit{et al.}, Phys. Rev. Lett. 96, 246103(2006) [2] J. Sun\textit{ et al.}, Phys. Rev. B (scheduled for publication 15 Oct 2007) [Preview Abstract] |
Saturday, October 20, 2007 8:15AM - 8:30AM |
E3.00002: Did Heisenberg's Uncertainty Principle Impact Foundational Concepts Unfavorably, by Displacing a Standing Wave Model for the Electron? Sean McNabb, Kaan Balam Matagamon, Sagamo Pawa Matagamon Heisenberg's succeeded in inducing Schr\"{o}dinger to recant his standing wave model for the electron. They subsequently successively received Nobel awards. On August 30, 2007, David Mc Leod stated: ``Dad, while I was learning high school chemistry, and was being taught the Heisenberg Uncertainty Principle, I said to myself, `This is BS!''' Son and ``Dad'' had been discussing their traveling wave/standing wave, TW/SW, model for the electron. Dave had discussed, in the context of beta decay, how an electron and an antineutrino were emitted together. Dave then said, ``An electron is an antiparticle.'' Because, a ``string-like'' electron had to have been a segment ``cut out of'' one of our neutron-string models. It had to have antinodes at either free end. One end, modeled as a transversely vibrating entity, had to ``eject'' the occupant for the loop to close. The TW/SW model cannot be a point or particle. De Broglie is correct, but The Principle should be recast: It is philosophically unsound. Quantum Mechanics, and String theory, could be foundational beneficiaries. Schr\"{o}dinger seems incomplete. [Preview Abstract] |
Saturday, October 20, 2007 8:30AM - 8:45AM |
E3.00003: New Insights Into the Role of Magnetism in High Temperature Superconductivity Samuel Emery, Barrett Wells, Hashini Mohottala, Joseph Budnick, Kim Lefmann, Niels Hessel Anderson, Christof Niedermayer, Niels Christensen, Fang-Cheng Chou Previous work by our group has determined that the low temperature phase diagram of super-oxygenated, superconducting, La$_{2}$CuO$_{4}$ consists of only a few line phases that are either superconducting (SC) or magnetic. Samples with doping levels between the stable phases will segregate into separate domains. This raises the question as to the nature of the interaction between SC and magnetic domains. We have begun a neutron scattering study of the magnetic behavior of our superoxygenated crystal. The oxidation state of our sample is such that we have a low-hole density superconducting phase (T$_{c}$= 30K) and a phase with higher hole concentration that has a stripe-like spin density wave (T$_{m}$= 40K). Elastic neutron scattering revealed a small field dependent growth of peak intensities, which is different from non-phase separated La$_{2-x}$Sr$_{x}$CuO$_{4}$. Using inelastic neutron scattering to probe the dynamic magnetism in our sample, we have created a preliminary model that allows us to separate the dynamic contributions of the SC and magnetic phases. This should be key in understanding how magnetic interactions might be responsible for Cooper pair formation. [Preview Abstract] |
Saturday, October 20, 2007 8:45AM - 9:00AM |
E3.00004: Fusion rates in adiabatically compressed ideal and non-ideal gases David W. Kraft We consider the mechanical compression of a dense plasma with reduced degrees of freedom such as may be effected by an electric discharge or by application of magnetic fields. The gas is assumed to undergo a reversible adiabatic compression and model calculations of the temperature increase are performed for one mole of deuterium initially at room temperature and pressure. Nuclear fusion rates resulting from primary fusion reactions and the corresponding energy releases are computed for both an ideal gas and a van der Waals gas. [Preview Abstract] |
Saturday, October 20, 2007 9:00AM - 9:15AM |
E3.00005: ``Sub-prime" Biophysics: Acoustic assessment of animal stress David Browning Animal welfare is of increasing concern. Vocalizations can be easily monitored and for some animals, such as the ``yip'' of a dog, stress is easily discernible. Unfortunately for many important farm animals, such as cows, sheep, and horses, the impact of stress on vocalizations appears to be more subtle. Our work is presently focused on the frequency spectra of horse whinnies. A whinny is comprised of two components; a tonal structure, and a varying frequency component or ``call.'' Results to date are presented on whether a horse can control this ``call'' so that there is a significant difference between a ``stressed'' whinny and a ``happy'' whinny. [Preview Abstract] |
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