Bulletin of the American Physical Society
Fall 2011 Meeting of the APS Prairie Section
Volume 56, Number 13
Thursday–Saturday, November 10–12, 2011; Cedar Falls, Iowa
Session G1: General Topics: Theory and Experiment |
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Chair: Cliff Chancey, University of Northern Iowa Room: UNI Center for Enery and Environmental Education Auditorium |
Saturday, November 12, 2011 9:00AM - 9:12AM |
G1.00001: Reconstruction of Objects in Random Media Based on Their Shadow Patterns Ben Rogers, Robert Wagner, Qichang Su, Rainer Grobe Methods for using laser light to detect multiple unknown objects inside of random media are discussed. The measured shadow pattern can be decomposed into its component ``eigenshadows'' by diagonalizing the covariance matrix. It is shown that the resolution of objects that are upstream and closer to the incoming laser light is lower than the resolution of objects further downstream, and techniques to improve the resolution of objects are also discussed. Finally, a method of detecting objects by minimizing $\chi^2$ while scanning through various positions for the object is introduced. [Preview Abstract] |
Saturday, November 12, 2011 9:12AM - 9:24AM |
G1.00002: Effect of random noise on a bio-optical imaging scheme Brandon Graybeal, Robert Wagner, Qichang Su, Rainer Grobe Simulations for detecting objects inside of biological materials by using laser light are presented. Our method uses the weighted shadow patterns of objects at fixed locations to ``mask'' one section of the detection region, so that objects in the unmasked region can be located by scanning through various locations and minimizing $\chi^2$. It is shown that when random noise is introduced, the method is very robust when only a single object is present in the medium but that detection of multiple objects can be very sensitive to noise. [Preview Abstract] |
Saturday, November 12, 2011 9:24AM - 9:36AM |
G1.00003: Multi-runner scheme for imaging Alexander Su, Robert Wagner, Qichang Su, Rainer Grobe A technique to locate rods inside of a highly scattering medium is presented. The detected shadow pattern which is cast by an incoming laser beam is used to reconstruct the location of the rods. The method is based on a scanning technique where a weighted, double-rod configuration scans through the medium and the weights of the rods' shadows are fitted to the observed shadow pattern. It is shown that one of the fitting weights vanishes when the location of the desired rod is found. Finally, it is demonstrated that the method is less sensitive to noise than a prior method based on minimizing $\chi^2$. [Preview Abstract] |
Saturday, November 12, 2011 9:36AM - 9:48AM |
G1.00004: Field-induced pair creation in fermionic and bosonic vacua Matthew Ware, Robert Wagner, Qichang Su, Rainer Grobe Using numerical solutions to quantum field theory, the creation of particle-antiparticle pairs from the vacuum due to a strong external localized electric field is explored. It is shown that the presence of an incoming fermion can suppress the creation of fermion-antifermion pairs by the external field, and the consequences of this fact for the so-called Klein paradox are discussed. In contrast to the fermionic system, an incoming boson enhances boson-antiboson creation rates through the process of stimulated emission. It is shown that this leads to an exponentional self-amplification of boson pairs in a supercritical potential well. [Preview Abstract] |
Saturday, November 12, 2011 9:48AM - 10:00AM |
G1.00005: Causality and relativistic localization in 1-d Hamiltonians Ben Shields, Robert Wagner, Qichang Su, Rainer Grobe Superluminal motion and its connection to causality is explored in the context of quantum mechanical systems. It is shown that, while the mean velocity of a quantum wave packet may be less than c, certain portions of the wavepacket may still spread superluminally. Criteria are developed that can be used to determine if a wavepacket is spreading superluminally, and these criteria are used to show that the relativistic Schrodinger equation is non-causal and that up to 8\% of the wavepacket may violate causality. It is also verified that the Dirac and Klein-Gordon equations are causal, and extensions of this work to quantum field theories are briefly discussed. [Preview Abstract] |
Saturday, November 12, 2011 10:00AM - 10:12AM |
G1.00006: QCD calculations with optical lattices Yuzhi Liu, Yannick Meurice By trapping cold polarizable atoms in periodic potentials created by crossed laser beams, it is now possible to experimentally create ``clean'' lattice systems. Experimentalists have successfully engineered local and nearest-neighbor interactions that approximately recreate Hubbard-like models on table tops. I discuss the possibility of using this new technology in order to: 1) calculate correlation functions and determinants for models with fermions, 2) design new systems with emergent local gauge invariance. [Preview Abstract] |
Saturday, November 12, 2011 10:12AM - 10:24AM |
G1.00007: Dynamics of two- and four- boson interactions in dressed vacuum states Andrew Vikartofsky, Robert Wagner, Qichang Su, Rainer Grobe We analyze the spatial and temporal dynamics of virtual particles in the vacuum states of one-dimensional $\phi^2$- and $\phi^4$-model systems. The properties of the vacuum state for the $\phi^2$-system can be found analytically, which allows us to compute all spatial and temporal correlations exactly. The momentum distribution of the vacuum virtual pairs is examined as well as the spatial and temporal correlations between virtual particles for both systems. We argue that almost all of the vacuum's properties can be explained in the usual particles terms. [Preview Abstract] |
Saturday, November 12, 2011 10:24AM - 10:36AM |
G1.00008: Non-destructive X-ray Spectroscopy Methods for use in Study of Iron Age-Persian Period Arrowheads's Mitchell Miller, Carlo Segre, Elizabeth Friedman, Jon Almer, Sarvjit Shastri, Heather Snow, Laura D'Alessandro, Lynn Swartz Dodd Non-destructive x-ray spectroscopy methods are commonly used to determine the composition and structure of unidentified samples.~ A novel application of these methods is to use a high energy ($>$80 keV) synchrotron source in the study of archeological artifacts thereby probing the bulk material instead of just the surface. Using x-ray fluorescence and diffraction, the raw materials and methods used in manufacturing arrowheads from several Iron Age-Persian Period Middle Eastern archaeological sites were investigated.~ The fluorescence spectrum provides information about the relative composition of the bulk while the 2D diffraction pattern can yield details about the composition of the majority bronze phase as well as highlight differences in thermo-mechanical techniques.~ The results obtained from analysis of the fluorescence spectra indicate that that the arrowheads are bronze, composed primarily of a leaded copper -- tin alloy.~ Additionally, after comparing the diffraction patterns to known standards, the percent weight of tin in the bronze alloys of select artifacts was determined. The addition of lead to copper-tin alloys, which would reduce the cost of the composite metal and improve the fluidity of the melt, may be more commonplace than previously thought.~ Data from both fluorescence and diffraction spectra will be presented. [Preview Abstract] |
Saturday, November 12, 2011 10:36AM - 10:48AM |
G1.00009: ABSTRACT WITHDRAWN |
Saturday, November 12, 2011 10:48AM - 11:00AM |
G1.00010: Charged Particle Interactions Based Upon Source-Sink Modeling Jon Eliason A conceptual particle interaction model is developed which considers the stable charged particles, electrons and protons, as sources and sinks, respectively, of Electrostatic Fluid (ESF). Their modeling as ESF sources and sinks provides a simple model and mechanism for action at a distance which agrees with empirical behavior. Since ESF is an intimate feature of electrons and protons, it inherently moves with bodies containing these particles, in contrast to the bodies moving through a generally distributed ESF medium. [Preview Abstract] |
Saturday, November 12, 2011 11:00AM - 11:12AM |
G1.00011: What if physics is wrong? Zhoudunming Tu Physics, an experiment-based science, seems to be the most appropriate subject in how to explain the inner workings of the world. We respect physics because it is based on facts that are perceived by our observations. However, what if we are not seeing the entire truth we seek? What if our observations are founded on sandy foundations? As humans, we desire to know what the truth is. Rene Descartes, a mathematician, philosopher, and physicist asked this question: \textit{what is the absolute truth in our universe? }I want to solve the same puzzle. Many people believe that physics will reveal the truth of our universe. But, what if physics is wrong? [Preview Abstract] |
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