Bulletin of the American Physical Society
2005 Joint Spring Meeting of the Texas Sections of the APS, AAPT, and Zone 13 SPS
Thursday–Saturday, March 3–5, 2005; Nacogdoches, TX
Session BA: APS III |
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Sponsoring Units: TSF Chair: Norman Markworth Room: Science Building Room 335 |
Saturday, March 5, 2005 10:00AM - 10:36AM |
BA.00001: Designing a Nuclear Device as a Learning Exercise David Kahl, Chad Huibregtse, Steve Abbott, Elizabeth Boatman, Elon Candea, Sarah Johns, Jason Marmon, Jared Nance, Eric Stall, John Stierna, Loren Warmington The goal of this project was to examine in detail the difficulties involved in designing and constructing a nuclear weapon. The research was initiated as a class project in a course on nuclear physics. The workload was divided into three primary sections: Acquisition and Enrichment of Fissile Materials; Bomb Physics; and Bomb Effects. Using only publicly available materials, we were able to successfully devise a step-by-step design for building a 20 KT uranium bomb, as well as detailing the processes for uranium refinement and the results of its detonation. Our work is relevant to the broader scientific community because it demonstrates that the major difficulty encountered in building an atomic weapon is acquiring fissile material. [Preview Abstract] |
Saturday, March 5, 2005 10:36AM - 10:48AM |
BA.00002: Modeling of Copper Indium/Gallium Diselenide Superlattices Steven Scurlock, Robert Friedfeld The copper indium/gallium diselenide superlattice is investigated numerically for different layer lengths of this particular lattice matched crystal. The main emphasis is on applying the Kronig-Penny model for the relevant band gap energies. By varying the sizes of the layers, the region where superlattice behavior should exist is determined. [Preview Abstract] |
Saturday, March 5, 2005 10:48AM - 11:00AM |
BA.00003: Alternative approach to dimensional scaling Robert Murawski , Anatoly Svidzinsky, Marlan Scully We will present a comparison between the D-scaling approach of Herschbach/Witten and an alternative form. The new approach is far less computationally expensive and introduces quantum numbers in a natural way, thus allowing one to calculate excited states without going to a 1/D expansion. The two approaches will be tested on the excited states of helium. [Preview Abstract] |
Saturday, March 5, 2005 11:00AM - 11:12AM |
BA.00004: Isoscaling parameters for light projectile and heavy target central HIC Armando Barranon, Jorge Lopez Several heavy ion collisions have been simulated bombarding heavy targets with light projectiles and using LATINO dynamical model, where a Pandharipande potential replicates binary interaction and fragments are identified via an Early Cluster Recognition Algorithm. Isoscaling parameters in the experimental range were obtained, confirming that Isoscaling relation holds for equilibrated compound nuclear sources as well as nuclear systems produced by dynamical fragment formation. Authors acknowledge financial support from Grant 2-4570.5 of the Swiss National Science Foundation and access to the computational resources of UAM-A and UTEP. [Preview Abstract] |
Saturday, March 5, 2005 11:12AM - 11:24AM |
BA.00005: Quantum control of the normal modes of benzene with ultrafast laser pulses Petra Sauer, Yusheng Dou, Ben Torralva, Roland Allen Remarkable innovations in laser technology have made it possible to create laser pulses with ultrashort durations (below 100 femtoseconds) and ultrahigh intensities (above 1 terawatt per cm$^{2}$). To understand the behavior of complex molecules and materials in this new regime of physics, chemistry, biology, and materials science requires innovative techniques which complement experiment and standard theory, and which can treat situations in which conventional approximations like the Born- Oppenheimer approximation, the Franck-Condon principle, and Fermi's golden rule are no longer valid. In this talk we describe a method that we are developing, semiclassical electron-radiation-ion dyanmics (SERID), which can be used to perform simulations of the coupled dynamics of electrons and nuclei in an intense radiation field. We have employed this technique in studying the normal modes of benzene, and the possibility of controlling these modes by optimizing the laser pulses that are applied to the molecule. Animations will be shown of particular normal modes, including the breathing and beating modes, illustrating their symmetries and other properties, and of the photodissociation of benzene when the laser pulse exceeds a threshold intensity. [Preview Abstract] |
Saturday, March 5, 2005 11:24AM - 11:36AM |
BA.00006: Quantum Potential and Chaos of the Kicked Rotor Yindong Zheng, Donald H. Kobe The de Broglie-Bohm approach to quantum mechanics implies trajectories similar to classical trajectories determined by classical forces, except that these quantum trajectories also have an additional quantum force. These quantum trajectories can be used to treat quantum chaos in a manner similar to the treatment of classical chaos. A quantum Lyapunov exponent can be calculated in a manner similar to a classical Lyapunov exponent. The quantum force is the negative gradient of a quantum potential. We show that the quantum potential is a fictitious potential in the sense that it is part of the quantum kinetic energy. Consequently, the quantum force is also a fictitious force. The results of the de Broglie-Bohm approach to quantum chaos agree with standard quantum mechanics only when the quantum potential happens to be zero. We apply the de Broglie-Bohm approach to study the quantum chaos of the kicked rotor. For this bounded system we use the method of Benettin, et al. to calculate both classical and quantum Lyapunov exponents as a function of the control parameter K. In addition to the stability regions in the chaotic sea for even multiples of $\pi$ associated with accelerator mode islands, we find new stability regions at odd multiples of $\pi$ associated with oscillating modes. We examine these regions both classically and quantum mechanically. [Preview Abstract] |
Saturday, March 5, 2005 11:36AM - 11:48AM |
BA.00007: Computing Energy Spectra for Quantum Systems Using the Feynman-Kac Path Integral N.G. Fazleev, J.M. Rejcek, J.L. Fry A method for calculating the first few energy eigenvalues for quantum systems using the Feynman-Kac path integral is presented. The exact analytical solution of the Feynman-Kac path integral for the infinite square well is presented and compared with numerical simulations approximated by random walk simulations on a discrete grid. Using the Laplace transform of the Feynman-Kac path integral and knowing the form of the eigenvalue expansion of the integral, it is possible to calculate the first few energy eigenvalues within an estimated uncertainty. The method provides exact values in the limit of infinitesimal step size and infinite time for the ground state. [Preview Abstract] |
Saturday, March 5, 2005 11:48AM - 12:00PM |
BA.00008: Searching for Lorentz Violation in Astrophysics Seiichirou Yokoo, Roland Allen Astrophysical, terrestrial, and space-based searches for Lorentz violation are briefly reviewed. Such searches are motivated by the fact that all superunified theories (and other theories that attempt to include quantum gravity) have some potential for observable violations of Lorentz invariance. We also review some new predictions of a specific Lorentz-violating theory: If a fundamental energy in this theory lies below the usual GZK cutoff, the cutoff is shifted to infinite energy; i.e., it no longer exists. On the other hand, if the fundamental energy lies above the GZK cutoff, there is a high-energy branch of the fermion dispersion relation which provides an alternative mechanism for super-GZK cosmic-ray protons. We also consider the dark matter problem from a new perspective: In Lorentz-violating supergravity, sfermions have spin 1/2 and other unusual properties. If the dark matter consists of such particles, there is a natural explanation for the apparent absence of cusps and other small scale structure: The Lorentz-violating dark matter is cold because of the large particle mass, but still moves at nearly the speed of light. Although the R-parity of a sfermion, gaugino, or gravitino is +1 in the present theory, these particles have an ``S-parity'' which implies that the LSP is stable and that they are produced in pairs. On the other hand, they can be clearly distinguished from the superpartners of standard supersymmetry by their highly unconventional properties. [Preview Abstract] |
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