Bulletin of the American Physical Society
2005 7th Annual Meeting of the Northwest Section
Friday–Saturday, May 13–14, 2005; Victoria, BC, Canada
Session F1: Plenary II |
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Chair: Ken Krane, Oregon State University Room: MacLaurin 144 |
Saturday, May 14, 2005 8:30AM - 9:06AM |
F1.00001: Orbital Mediated Tunneling Spectroscopy and Imaging Electron Transport Pathways Invited Speaker: Chemical specificity within the scanning tunneling microscope (STM) is significantly enhanced by performing STM based orbital mediated tunneling spectroscopy (OMTS). Structurally similar compounds having similar STM images are easily differentiated by their OMTS. The principal mechanisms for OMTS will be discussed and experimental OMT bands will be compared to ultraviolet photoelectron spectra and to first electron affinity and ionization levels estimated from electrochemical data. Evidence will be presented that the molecular potential is sometimes fixed at the substrate potential and the consequences of failure of this condition will considered. Constant current images acquired at voltages near resonance values reflect the spatial distribution of the orbitals involved in the transport process. Maps of local electron transport on a sub-molecular scale will be presented. [Preview Abstract] |
Saturday, May 14, 2005 9:06AM - 9:42AM |
F1.00002: Precision Cosmology with Weak Gravitational Lensing Invited Speaker: The deflection of photons by massive structures in the universe gives rise to a small, but measurable net alignment in the shapes of distant galaxies. The measurement of this ``weak gravitational lensing'' effect enables us to study the dark matter distribution in the universe directly, making it a powerful tool for observational cosmology. By itself, or in combination with other methods, such as CMB, weak lensing provides tight constraints on a range of cosmological parameters. This relatively new area of research has developed quickly in the past few years, and the prospects for the future are excellent. Several large surveys are underway or being planned with the aim to provide unique, tight constraints on the properties of the dark energy and dark matter. In this talk I will discuss the theory and how the measurements are made. I will review recent progress in this rapidly evolving field, and demonstrate its potential through some interesting applications. [Preview Abstract] |
Saturday, May 14, 2005 9:42AM - 10:18AM |
F1.00003: Teaching Physics to Blind and Dyslexic Students Invited Speaker: Teaching and learning physics generally breaks down into three types of activity:\newline \newline {\textbullet} Face to face communications (eg lectures, office sessions)\newline {\textbullet} Labs\newline {\textbullet} Written communication (eg lecture handouts, written homework, quizzes and tests) pose difficulties for students who are blind, low vision, dyslexic, or have other print disabilities. \newline \newline Common sense guidelines can facilitate face-to-face communications, and careful division of tasks can make labs worthwhile to students with print disabilities. This presentation will focus on the most difficult challenge -- that of written communication. Presently written materials are usually communicated to and from such students by people whose job is to ``make materials accessible.'' This is virtually never a satisfying experience for either the physics instructor or a conscientious student. Several new computer access technologies will be demonstrated -- ones that now permit students with print disabilities direct access to well-written electronic materials that include text, math, and graphics. The students do ``pencil and paper'' work using special computer applications whose final results for homework or tests are printed or submitted electronically to the faculty member or TA. Virtually all ``written'' information in first world educational institutions is generated on a computer, so very little extra effort by faculty members is needed to assure that students with print disabilities who use these new technologies can receive and return written materials. [Preview Abstract] |
Saturday, May 14, 2005 10:18AM - 10:48AM |
F1.00004: COFFEE BREAK
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Saturday, May 14, 2005 10:48AM - 11:24AM |
F1.00005: Nuclear Rotation: New Perspectives at Low Energy and Low Spin Invited Speaker: Nuclear rotation is one of the fundamental low-energy collective modes established in nuclei. It has been a major organizing framework for the structure of deformed nuclei for over 50 years. This is manifested in the observation of numerous rotational bands in nuclei, primarily via energy patterns which very closely follow an ``I(I+1)'' pattern. (Among the structural insights provided, a leading one which rotational energy spacings reveal is that not all of the nucleus is rotating.) Nuclei that do not follow a rotational energy pattern are classified as ``vibrational'' (very few examples) or ``rotational-vibrational'' (many examples), with correspondingly more complicated theoretical descriptions. A recent survey of electric quadrupole transition probabilities in nuclei[1] reveals that rotational values persist far into non-rotational regions. This raises the question of whether energy patterns are a reliable indicator of rotational behavior. The nuclear rotational degree of freedom will be introduced, the transition probability data will be presented, and some ideas about what may be happening will be suggested. [1] J.L.Wood, W.D.Kulp, and J.M.Allmond, Bull.Am.Phys.Soc. 49 (2004), p.42. [Preview Abstract] |
Saturday, May 14, 2005 11:24AM - 12:00PM |
F1.00006: Studying Astrophysics and Particle Physics with Gamma Rays: what we may learn with the upcoming GLAST mission Invited Speaker: The gamma-ray sky, for energies above 30 MeV, has been relatively poorly studied. Most of our current knowledge comes from observations made by the EGRET detector on CGRO, which produced many discoveries, opening up a new field of astronomy. It found that the luminosities of many objects peak in this energy band, that the spectra of gamma-ray bursts extends to at least GeV energies, and that intense gamma-ray flares are a common feature of many gamma-ray sources. This talk will focus on the three periods in the life of a gamma ray: How is it produced, which requires extreme environments in astrophysicsal objects, or new physics like WIMP dark matter annihilation; what can be learned as the photon propagates to us, absorption or dispersion; and how we detect it, with a discussion of the design of the successor to EGRET, GLAST. GLAST, for Gamma-ray Large Area Space Telescope, is a DOE/NASA mission to be launched in to low Earth orbit in 2007. It will have significantly improved capability over EGRET, satellite-based experiment to measure the cosmic gamma-ray flux in the energy range 20 MeV to $>$300 GeV. With a sensitivity that is more than a factor 30 greater than that of the EGRET. [Preview Abstract] |
Saturday, May 14, 2005 12:00PM - 12:36PM |
F1.00007: The Legacy of Einstein's Photoelectric Effect: From Light Quanta to Quantum Phenomena in Solids Invited Speaker: The photoelectric effect, discovered by Hertz in 1887 and explained by Einstein in 1905 on the basis of the revolutionary hypothesis of light quanta, marked the beginning of photoelectric spectroscopy, one of the most active fields in modern science and technology. Owing to recent technical progress, in particular to the development of third generation synchrotron sources, the last decade witnessed a renaissance in this technique and its applications. In this context, angle-resolved photoemission spectroscopy (ARPES) has emerged as the most powerful method of studying the momentum-resolved low-energy electronic structure of solids. Nowadays ARPES enables the detailed mapping of electronic band structures and Fermi surfaces as well the study of many-body quantum phenomena in solids. In this talk I will review the present state of the technique and, by presenting recent experimental results on the high-temperature copper-oxide superconductors, I will illustrate that state-of-the-art ARPES is a unique tool for momentum-space microscopy on novel quantum materials. [Preview Abstract] |
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