Bulletin of the American Physical Society
2005 New England Sections of the APS and AAPT Joint Fall Meeting
Friday–Saturday, October 14–15, 2005; Burlington, VT
Session A2: Poster Session |
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Room: Burlington DoubleTree Hotel 5:30-7:00pm |
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A2.00001: Effective Mass of Vector Polarons Charles Foell, Dennis Clougherty We consider the vector polarons of a one-dimensional model of an electron in a doubly (or nearly) degenerate band that couples to two elastic distortions, as described previously by Clougherty and Foell [1]. A variational approach is used to analytically calculate effective masses of the three types of vector polarons. The effective mass to band mass ratios are compared to the numerical results of a related model by Hock, Nickisch and Thomas [2] in the region of parameter space where there is overlap. \newline \newline [1] D. P. Clougherty and C. A. Foell, Phys. Rev. B 70, 052301 (2004). \newline [2] K. -H. Hock, H. Nickish and H. Thomas, Helv. Phys. Acta, 56, 237 (1983). [Preview Abstract] |
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A2.00002: Using randomness for coherent quantum control Lea Santos, Lorenza Viola Dynamical decoupling methods consist of repetitive sequences of control operations, whose net effect is to coherently modify the natural target dynamics to a desired one. A general framework for investigating randomized decoupling schemes has been recently introduced by Viola and Knill [Phys. Rev. Lett. \textbf{94}, 060502 (2005)], based on designing the control propagator according to a random rather than deterministic path. General bounds on worst-case error probability indicate that random decoupling schemes may outperform their cyclic counterpart in situations where a large number of elementary control operations are required or when the interactions to be removed are fast fluctuating. A quantitative analysis of this new technique is developed in the simplest control scenario of a single qubit. We compare the performance of random and deterministic methods in switching off unwanted phase evolution and decoherence. A variety of dynamical regimes, including semiclassical and quantum decoherence models are considered, and different control protocols are examined. Besides providing a physical picture of random decoupling, our analysis identifies situations where randomization may be advantageous over deterministic design. [Preview Abstract] |
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A2.00003: The effects of coated surfaces on rubidium polarizations Paul Abed, Mark Rosenberry Certain applications of alkali optical pumping (e.g. polarized electron generation, storage of light) benefit from the use of minimal buffer gas pressure. Under these conditions, the interactions with the surface of the container become crucial in determining the polarization. We are working to improve the polarization lifetime of rubidium atoms in both glass and stainless steel containers, through the use of paraffin and drifilm coatings. Some model predictions and preliminary data will be presented. [Preview Abstract] |
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A2.00004: Progress of the Laser Spectroscopy Program at Bridgewater State College Gregory Surman, Brian Kieth, Edward Deveney We report on the development of our laser spectroscopy program at BSC; our new 100 mW Toptica tunable diode laser and some preliminary measurements on Rb on our way toward Doppler-free saturated absorption spectroscopy and 1-D cooling and trapping. [Preview Abstract] |
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A2.00005: Infrared Studies of Titanium-Containing Vitreous Silica Carrie E. Black, Christopher C. Homes, David Y. Smith The reflectivity of samples of Corning's ULE glass (7.5{\%} Ti and 92.5{\%} silica), was measured from 18 cm$^{-1}$ to 30000 cm$^{-1}$. The refractive index and extinction coefficient were then calculated using the Jahoda-Velicky dispersion relation. The resulting infrared absorption spectrum is almost identical to that of vitreous silica with the exception of a new absorption band at 941 cm$^{-1}$. The negligible change in the vitreous silica part of the absorption is taken to imply that, at the concentrations present, titanium has little effect on the SiO$_{2}$ network and the environment of Si$^{4+}$ ions. The phase diagram for TiO$_{2}$-SiO$_{2}$ systems and titanium EXAFS measurements$^{2}$ indicate that titanium is tetrahedrally coordinated by O$^{2-}$ ions in ULE glass, i.e., it substitutes for Si$^{4+}$. On this basis the new 941 cm$^{-1}$ band is attributed to an antisymmetric stretching mode of Ti-O-Si units, corresponding to a perturbation of the prominent Si-O-Si antisymmetric stretching mode$^{3}$ seen at 1076 cm$^{-1}$ in vitreous silica. 2. R. B. Greegor, \textit{et al}. J. Non-Crystalline Solids \textbf{55}, 27 (1983). 3. C. T. Kirk, Phys. Rev. \textbf{38}, 1255 (1988). [Preview Abstract] |
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A2.00006: Liposomes and Sonoporation Junru Wu, Di Chen, Jason Pepe, Benjamin E. Himberg, Mercedes Ric\'{o}n A method to prepare liposomes is presented. Liposomes made in our laboratory were characterized acoustically and optically. The phase velocity and attenuation of liposomes in suspension (concentration = 10$^{9}$/mL) were measured ranging from 2 to 14 MHz using ultrasound spectroscopy. Using the liposomes, anti rabbit IgG conjugated with Alexafluor 647 was delivered into Jurkat cells in suspension by 10 {\%} duty cycle ultrasound tonebursts of 2.2 MHz (the \textit{in situ} spatial peak-pressure amplitude = 80W/cm$^{2})$ with an efficiency of 13 {\%}. It has been experimentally shown liposomes may be an alternative stable agent to Optison$^{\mbox{{\textregistered}}}$ for delivering macromolecules into cells. [Preview Abstract] |
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A2.00007: Ultrasonic Spectroscopy for Characterization of Polymer Composites Christopher Layman, Ruey-Bin Yang, Sanjeeva Murthy, Junru Wu Ultrasonic spectroscopy can be used to quantitatively determine the role of spherulites, their size and distribution on the mechanical properties of semicrystalline polymers. As a first approximation, spherultic polymers are modeled as a material with spherical inclusions in an amorphous matrix. This two-phase composite model is then physically realized by embedding glass microspheres in an epoxy. The dynamic mechanical properties of these composites are experimentally determined by measuring their acoustic properties, phase velocity and attenuation. Acoustic scattering theories are then applied to this model to test their predictive capabilities for the real composite's mechanical properties. [Preview Abstract] |
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A2.00008: Investigation of the interface structure in sputtered WSi$_{2}$/Si multilayers by in-situ synchrotron X-ray scattering. Yiping Wang, Hua Zhou, Lan Zhou, Randall Headrick, Albert Macrander, Ahmet \"{O}zcan, Karl Ludwig We report on the growth of WSi$_{2}$ and Si amorphous thin films by dc magnetron sputtering in a vacuum chamber with 10$^{-9}$ Torr base pressure. In-situ synchrotron X-ray scattering with high temporal resolution has been employed to probe the surface and interface roughness evolution during film deposition. X-ray reflectivity simulations were performed using the IMD software package. It is found that the structure of WSi$_{2}$/Si multilayers is with an alternately smooth and rough interface. The ion energy and flux assisting the growth may play a role in inducing this asymmetry in the interface roughness. [Preview Abstract] |
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A2.00009: Ion-enhanced Viscous Flow Mediated Ripples on Sapphire Surface Hua Zhou, Yiping Wang, Lan Zhou, Randall L. Headrick, Ahmet S. \"{O}zcan, Yiyi Wang, G\"{o}zde \"{O}zaydin, Karl F. Ludwig, Jr., D. Peter Siddons In this work, a study of ripple formation on sapphire surface by ion sputtering is carried out to investigate surface roughing mechanism of energetic ion bombardment, and ion irradiation induced surface relaxation mechanism. Well-ordered surface pattern formation through a surface instability induced self-organization process provides great application potentials in magnetic media for information storage, and quantum wires/dots for electronics and photo-electronic devices. Surface characterization by in-\textit{situ} synchrotron grazing incidence small angle x-ray scattering (GISAXS), off-specular x-ray diffuse scattering (XDS) and ex-\textit{situ }atomic force microscopy (AFM) indicates that the characteristics (wavelength, shape and amplitude) of sapphire ripples can be varied over two orders of magnitudes (30nm to 2000nm) by changing the ion incidence angle, ion energy and temperature. Within the linear Bradley-Harper (B-H) theory regime, the ion induced viscous flow (IVF) fits the general trends of the data. However, anomalous smoothing unpredicted by current models is observed near normal incidence. A relation of the smoothing characteristic time (\textit{$\tau $}) versus ion energy is extracted to better understand this deviation. [Preview Abstract] |
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A2.00010: Gauging Student Response to Active Learning in the Lab Tracy Hodge The difficulty in implementing curriculum change in the college classroom centers around two problems: confronting student expectations about what will be expected of them in a ``typical'' science class; and convincing faculty that the outcome is worth the additional effort needed to substantially change their time-honored teaching methods. In order to gauge the effectiveness and feasibility of modifying the introductory physics lab at Salem State College into an active learning environment, I piloted a 4 week digital electronics unit modeled after David Sokoloff's RealTime Physics. The goal was to gauge student response to the active learning style, and to demonstrate that the methods used in RealTime Physics could be implemented at Salem State with the equipment we have on hand. This presentation will summarize results of the pilot program and consider issues for the future of the lab program. [Preview Abstract] |
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A2.00011: Working Model of an Atomic Force Microscope Kirsten L. Bonson, Michael J. Hamblin, David A. Hammond, Randall L. Headrick Relatively few laboratory experiments are available for introductory lab courses relating to nanoscience and nano- technology. In order to explain the working principles of an atomic force microscope (AFM) to an introductory level physics class, we have created an inexpensive working model of an AFM using a modified phonograph stylus in place of the AFM cantilever and tip. The sample to be studied is positioned under the stylus using a micrometer stage, and a 10 mW laser diode is used to produce a beam, which reflects off a very small mirror glued to the end of the stylus. No electronic detection is used, rather students can measure the deflection of the tip directly from the movement of the laser beam on a piece of graph paper placed 50 cm from the mirror. The laser beam is deflected roughly a centimeter for each 10 microns of stylus deflection, making it simple for students to collect data. A one-dimensional trace is typically performed, however the instrument could be easily modified to produce a full two-dimensional scan. [Preview Abstract] |
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A2.00012: Convective Rainfall in the North Central and Northeastern United States during the Spring, Summer and Fall Seasons Richard Stimets, Stephanie Lane, Afrim Alimeti Fifteen-minute precipitation data from over 1000 stations covering 26 states of the north central and northeastern United States for the 30-year period 1971-2000 has been analyzed to produce maps of the amounts and diurnal distributions of four levels of convective rainfall. Overall, as the level increases, the maps show increasing geographical nonuniformity, increasing fall/spring asymmetry skewed toward the fall, and significant changes of up to five hours in the dominant hour of convective rainfall. These results can serve as a stringent test of climate models which attempt to predict the amounts and timing of convective rainfall under current conditions and under the altered conditions expected from global warming. Clearly, many factors other than diurnal solar heating, such as terrain type, latitude, proximity to large bodies of water and continental-scale airflows are important and must be represented better by climate models if the models are to make trustworthy predictions about changes in precipitation due to global warming. Improved models should also include multiple levels of convective rainfall. [Preview Abstract] |
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A2.00013: An Analysis of Ted Williams' Red Seat Homerun: The Physics of Home Run Trajectories. Elizabeth Dennis, Andrew Chap, Edi Naco, Timothy Roach, Matthew Koss Baseball, the great American pastime, has been played in some manner since 1744. While the rules, names, and uniforms have changed and evolved, the basic physical principles of balls in flight have not. By examining the forces on a baseball, we calculated and studied the trajectory of batted balls based on models by Adair, Watts and Bahill, and Sawicki et. al.. We calculated several possible trajectories from these models for one very impressive homerun. On June 9, 1934, Ted Williams hit a homerun at Fenway Park that was said to go 502.5 feet before it landed on the head of Joseph Boucher seated in Section 42, Row 37, Seat 21. How far would the ball have gone if its path was not impeded by Mr. Boucher's straw hat? The answer depends on several parameters including ball rotation, velocity, launch angle, and prevailing winds. A key feature of this homerun was that it was hit on a day of 20 mph tail winds and low humidity. According to our calculations, Ted Williams or another of the greatest players of all-time, could have hit homerun this far. The most probable case, in our opinion, seems to occur at an initial velocity of 118 mph, with a launch angle of 28 degrees, and a rotation rate of 1800 rpm. However, this is at the extreme of what appears to be humanly possible. [Preview Abstract] |
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