Bulletin of the American Physical Society
2006 Joint Spring Meeting of the New England Section of APS and AAPT
Friday–Saturday, March 31–April 1 2006; Boston, Massachusetts
Session A: Poster Session |
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Sponsoring Units: NES Chair: Karl Ludwig, Boston University Room: Photonics Building 206 Lobby, 5:40pm - 7:00pm |
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A.00001: Undergraduate Reseach in Color Center Production and Photodegradation using Retroreflecting Glass Beads Everett Kysor, Russell Harkay A project has been initiated at Keene State in which UV light from a Deuterium arc lamp is used to produce or bleach color centers in a wide variety of materials, including reflective glass beads used for highway marking, alkali halides, and other transparent materials. The glass beads have a very high refractive index due to the inclusion of metallic impurities. Practical applications include varying the refractive index of a material by adding or bleaching (neutralizing) color centers, which are, in themselves, in interesting manifestation of the particle-in-a-box problem encountered in modern physics. Another practical outcome of the ongoing project is to determine the overall effect of exposure to UV light on the transmission and optical parameters of materials normally exposed to sunlight. As a sidebar experiment, work was performed in which micron-size glass beads were used to simulate two-dimensional arrays with a laser playing the role of x-rays in forming diffraction patterns. [Preview Abstract] |
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A.00002: The Spin on the ``Source Surface'' of the Solar Wind Gary Parker This observational study of coronal rotation is based on the K-coronameters aboard SOHO, the SOlar and Heliospheric Observatory. Sunspots occur within 35 degrees of the equator. Extensions of active regions into the atmosphere persist for sufficiently long that their sightings at the Sun's edge serve as timing markers to measure rotation. But magnetic structures other than those originating in active regions also reach the base of the solar wind, and the strongest rotation signal in 2002 is from latitudes higher than sunspots and is a feature of the neutral sheet of a tipped magnetic dipole. Come see the pictures. [Preview Abstract] |
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A.00003: On Large Volume K\"ahler Inflation Per Berglund, Joan Simon, Licia Verde, Raul Jimenez, Vijay Balasubramanian We show that cosmological observables can constrain the topology of the compact additional dimensions predicted by string theory. [Preview Abstract] |
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A.00004: Potential ``Circles in the Sky" matches for simple topologies of the Universe Dusan Maletic If universe characteristic size is smaller than the radius of the SLS, it can intersect itself and we could observe a set of pairs of matching circles in the CMB radiation. Following the statistics proposed by Cornish, we analyze the WMAP ILC map. We apply the simplified Kp0 data mask, avoiding Galactic foregrounds. We do not consider any circles completely or partially falling within $7^{\circ}$ of the Galactic plane or within $20^{\circ}$ from the Galactic center. We do not average or smooth the data as the expected thickness of the circles can be estimated to be of the same order as the WMAP data resolution. By the nature of this phenomenon circles should be sharply defined. We examine statistics of the best matches for the CMB circles expected in the cases of Quaternionic, T3, Seifert-Weber and Poincare Dodecahedral topologies. We limit our search to the circles of the sizes between $8^{\circ}$ and $16^{\circ}$ due to the reasonable expectations related to the applied data cuts of the WMAP map and the available resolution. Due to the latter we step the matching circle coordinates during the search in the $0.5^{\circ}$ increments as well as the circle sizes. We consider only the circles of exactly matching sizes because for the topologies considered it would not be Physical to match differently sized circles. As a result we provide circle sets most likely hinting the proposed set of possible topologies of the Universe. [Preview Abstract] |
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A.00005: Revisiting the Posibility of Resonant Decay of Axions into Photons Andrew Pawl We revisit the possibility that the coherently oscillating axion field undergoes resonant decay through its anomaly- generated coupling to the electromagnetic field. Early treatments of this process assumed a Mathieu-type resonance and suppression of decay due to the large (relative to the axion mass) electron plasma frequency at the time of onset of axion field oscillation. We explore the validity of these assumptions both analytically and numerically. [Preview Abstract] |
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A.00006: Random and Non-Random Placement of Rare Earth Ions in an Yttrium Aluminum Garnet (Y$_{3}$Al$_{2}$(AlO$_{4})_{3 })$ Crystal Jeremy Tudisco, John Collins When ionic insulating solids are doped with rare earth or transition metal ions, the spectroscopic properties of those ions depend on their concentration and distribution in the crystal. The efficiency of some processes, such as non-radiative energy transfer among the ions, depends on the details of their distribution, and interpreting the data requires an explicit or implicit assumption regarding that distribution. Their distribution is often assumed to be either random, or less realistically, spread evenly throughout the crystal. In this work, we construct a virtual crystal, and place dopant ions in randomly and nonrandomly, and then study the resulting distributions. We constructed a laser crystal, Yttrium Aluminum Garnet (YAG), containing up to 160,000 atoms (1000 unit cells). The doping process was simulated by selecting particular Yttrium ions, and substituting them with ions of a different type. This simulates the doping of rare earth ions, which are known to favor substituting at Yttrium sites. This doping was done at various concentrations. The random distribution was simulated with a ``random'' number generator. Non-random substitution of ions was also accomplished in a way that mimicked attractive and repulsive forces among dopant sites. For each ion we found the distance to its nearest neighbor and plotted the occurrence of each nearest neighbor distance. We batch-processed (1000 runs) the program in order to find an average distribution of the ions. [Preview Abstract] |
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A.00007: How to Explain the Green Flash |
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A.00008: Student understanding of differentials and the Maxwell relations of thermodynamics |
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A.00009: PHOTON2 Program Overview |
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A.00010: Optical Characteristics of Nd-doped PLZT Ceramic Laser Materials at Different Temperatures and Nd Concentrations Pi Ling Huang, Andrew Durocher, Xuesheng Chen The neodymium ion (Nd$^{3+}$) doped PLZT, is a newly developed transparent ceramic laser material that possesses great potentials for making high-power and high-efficient lasers. A major focus in this research is to investigate temperature and Nd$^{3+}$ concentration dependence of absorption of this material in the wavelength range from 600 to 900 nm. The samples investigated are 0.5\% and 1\% Nd doped PLZT's, each being 1 mm thick; temperature of the sample is being controlled at several chosen temperatures from 30 to 300K. The absorption peaks are found to be narrow, thus distinguishable at low temperature, but the lines are broadened as temperature increases. The absorption intensity and peaks can also change with temperature. The absorption peaks reveals what wavelengths the materials absorb well, which is critical in determing what kinds of pump light sources to use. This research provide critical information on choosing appropriate critical parameters such as temperature and concentration for the development of high-efficiency lasers with this new kind of the transparent ceramic laser materials, Nd$^{3+}$:PLZT. Results and conclusions will be presented in details at the meeting. [Preview Abstract] |
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