Bulletin of the American Physical Society
2009 APS March Meeting
Volume 54, Number 1
Monday–Friday, March 16–20, 2009; Pittsburgh, Pennsylvania
Session B13: SPS Undergraduate Research I |
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Chair: Gary White, American Institute of Physics Room: 309 |
Monday, March 16, 2009 11:15AM - 11:27AM |
B13.00001: Introductory Physics Experiments Using the Wiimote William Somers, Frank Rooney, Romulo Ochoa The Wii, a video game console, is a very popular device with millions of units sold worldwide over the past two years. Although computationally it is not a powerful machine, to a physics educator its most important components can be its controllers. The Wiimote (or remote) controller contains three accelerometers, an infrared detector, and Bluetooth connectivity at a relatively low price. Thanks to available open source code, any PC with Bluetooth capability can detect the information sent out by the Wiimote. We have designed several experiments for introductory physics courses that make use of the accelerometers and Bluetooth connectivity. We have adapted the Wiimote to measure the: variable acceleration in simple harmonic motion, centripetal and tangential accelerations in circular motion, and the accelerations generated when students lift weights. We present the results of our experiments and compare them with those obtained when using motion and/or force sensors. [Preview Abstract] |
Monday, March 16, 2009 11:27AM - 11:39AM |
B13.00002: Binary Orbital Motion of Electrically Charged Spheres in Weightlessness. Lulu Li, Brad Atkins, Gavin Franks, Joshua Fuchs, Chase Sliger, Jennifer Thompson The similar mathematical forms of Coulombs' Law of Electrostatics and Newton's Law of Gravitation predict that two oppositely charged spheres should be able to move in a binary orbit about their center of mass using only the electric force as the force of attraction. To test this prediction, we conducted an experiment in July 2008 aboard a specialized C-9B aircraft in NASA's Microgravity University Program which simulates the conditions of weightlessness. We successfully achieved multiple binary orbits between the two spheres. The orbital motion was analyzed using VideoPoint software to measure the orbital interaction of the spheres. [Preview Abstract] |
Monday, March 16, 2009 11:39AM - 11:51AM |
B13.00003: Dynamics of a charged Kapitza's pendulum interacting with radiation in thermal equilibrium Jorge Hernandez Gomez, Paulina Pradel Soto The considered system is a Kapitza's pendulum that consists of a disk that spins at constant angular velocity, from which edge is attached a massless rigid rod with an electrically charged bob. The system is studied theoretically and experimentally. The motion equations are settled and solved both, analytically under the small oscillation assumption considering the interaction of the system with black body radiaton as a perturbation, and in the general case using numerical algorithms. The pendulum's dynamics is studied varying both initial conditions and parameters in small steps. In order to identify regions of stable and chaotic motion, Lyapunov's exponents are calculated. Phase and configuration spaces are plotted to notice periodical and erratic behaviors. Poincare sections and fast Fourier transforms are obtained to identify resonance cases. [Preview Abstract] |
Monday, March 16, 2009 11:51AM - 12:03PM |
B13.00004: Electrical energy dissipation in superconducting niobium rings E. M. Dowdell, K. M. Chiola, E. T. Rosauri, J. D. Hettinger Niobium rings were made from films synthesized using sputtering process. Rings and wires were defined in the films using standard photolithographic techniques followed by wet etching. Three rings were fabricated with different diameters and wire widths. One microbridge was created for direct electrical transport measurements. V-I characteristics of the superconducting niobium microbridge were measured at temperatures below 7K and at magnetic fields up to 2T. Dissipation was induced in the superconducting niobium rings by ramping the magnetic field and employing Faraday's Law. The current induced was measured through the magnetic moment and the simple expression $\mu $=IA. We will correlate the magnetically induced measurements with those made directly on the microbridge to investigate this method as a technique for extending transport measurements to lower dissipation levels. [Preview Abstract] |
Monday, March 16, 2009 12:03PM - 12:15PM |
B13.00005: Surface plasmon enhancement of fluorescence on gold nanogratings Stephanie Wiele, Iuri Gagnidze, Jennifer Steele This work focuses on using surface plasmons (SPs) excited on gold wire gratings to enhance the yield from fluorescent molecules. SPs enhance fluorescence by amplifying the electromagnetic near-field that excites the fluorophore as well as providing additional decay channels for the fluorphore. Although it has already been shown that SPs excited on metal nanoparticles can enhance fluorescence, SPs excited on gratings offer several advantages over nanoparticles. Because SPs are excited by the diffraction orders of the grating, changing the angle of incidence of light will change the SP wavelength. The SP excited on the grating can then be tuned on a single plasmonic substrate to overlap the absorption and emission spectrum of many different fluorophores. The ability to tune the SP wavelength through both the absorption and emission wavelength of the fluorophores on a single substrate will give greater insight to how SPs enhance fluorescence and how to maximize the fluorescence enhancement for various biosensing applications. [Preview Abstract] |
Monday, March 16, 2009 12:15PM - 12:27PM |
B13.00006: Diffusive Behavior of Lipid Rafts in Multicomponent Membranes Michael G. Lester, Mohamed Laradji, P.B. Sunil Kumar The diffusion of nanoscale lipid domains (also known as lipid rafts) in multicomponent membranes in the liquid-liquid coexistence region of the phase diagram is investigated via extensive dissipative particle dynamics simulations. In particular we investigated the effect of membrane diameter and shape (curvature) on the diffusivity of the lipid domains. Our results indicate that the domains exhibit Brownian motion, {\em i.e.} the center of mass mean square displacement $(\Delta R)^2=4 Dt$, with the diffusion coefficient decreasing as the domain radius, $r$, is increased. More specifically, we found that $D\sim 1/r$, {\em i.e.} the diffusion of the domains is mainly impeded by viscous drag due to solvent surrounding the membrane. Although the data can also be fitted with the logarithmic expression due to Saffman and Delbr{\"u}ck\footnote{Saffman and Delbr{\"u}ck, Proc. Nat. Acad. Sci. {\bf 72}, 3111 (1975)} $D\sim \ln(1/r)$ describing diffusion where the membrane viscosity plays an important role, the later fit is found to be poorer than that with $D\sim 1/r$. [Preview Abstract] |
Monday, March 16, 2009 12:27PM - 12:39PM |
B13.00007: AC Magnetic Susceptibility Probe for Use in a Commercial SQUID Magnetometer J.D. Cohen, D.M. Pajerowski, M.W. Meisel An AC magnetic susceptibility probe, employing a typical set of mutual inductance coils, has been constructed for operation in a commercial SQUID magnetometer operating down to 1.7 K and up to 7 T. The primary ($\sim$1000 turns) and counterwound secondary (each $\sim$1300 turns) coils were wound with 44 AWG Cu wire on a Kapton tube possessing an ID of 6.4 mm. The ensemble of coils is $\sim$30 mm long and has an OD of 8.7 mm, thereby allowing clearance into the sample region of the SQUID magnetometer. One variation of the probe included optical fibers that passed down the center of the stainless steel support rod. The detection electronics involve a lock-in amplifier and the experiment is controlled by LabView software. Typical AC (1 Hz - 1 kHz) fields of $\sim$10 $\mu$T afford the study of the temperature, frequency, and dc-field bias dependencies of magnetically interesting samples such as the spin ice material Ho$_{2}$Ti$_{2}$O$_{7}$ $[1]$ and nanoparticles of Prussian blue analogs $[2]$.\\ $[1]$ M. Orend\'{a}\v{c} et al., elsewhere in these proceedings.\\ $[2]$ D. M. Pajerowski, F. A. Frye, D. R. Talham, and M. W. Meisel, New J. Phys. 9 (2007) 222. [Preview Abstract] |
Monday, March 16, 2009 12:39PM - 12:51PM |
B13.00008: Recreation of Natural Optical Phenomena Tiffany Paonessa, Peter Sheldon This project was undertaken to study and fully understand optical atmospheric phenomena. Research was done on the structure and formation of colorful atmospheric phenomena including, but not limited to, primary, secondary, and supernumerary rainbows, halos, parhelia, and glories. This study also undertakes an attempt to create some of these phenomena. Using hand-made epoxy crystals for ice, a round bottom flask as a water droplet, and a high-powered halogen lamp for sunlight, primary, secondary, and supernumerary rainbows and halos were created and photographed. [Preview Abstract] |
Monday, March 16, 2009 12:51PM - 1:03PM |
B13.00009: Visualization of fracture precursors in vitreous silica: study of under- and over coordinated ions Frank Jones, Romulo Ochoa, Deborah Knox We have conducted classical molecular dynamics fracture studies of vitreous silica. A new visualization program was designed to observe the fracture process of the sample as a whole. The program also allows users to highlight and focus on the under- and over coordinated oxygen and silicon ions. A BKS potential was utilized to model the ionic interactions. DL-POLY* was the program used to perform simulations. Amorphous silica samples were generated at high temperatures; through a series of quenching and equilibration periods vitreous silica was obtained at room temperature. This method resulted in samples having, initially, a number of under- and over coordinated ions (less than one percent of all ions) that were randomly distributed. Radial distributions functions were obtained to verify the amorphous structure of the samples. Stress was applied by uniaxially straining the samples at various rates. As a sample was strained there was an increase in under coordinated ions with seemingly no correlation to the region where the sample would break. In all our simulations the under coordinated ions concentrated in the vicinity of the breakage region a few picoseconds before fracture occurred. *CCLRC Daresbury Laboratory, UK [Preview Abstract] |
Monday, March 16, 2009 1:03PM - 1:15PM |
B13.00010: Determining the Onset of Amorphization of Crystalline Silicon due to Hypervelocity Impact C. Shane Poletti, Martina E. Bachlechner Atomistic simulations were performed to study a hypervelocity impactor striking a silicon/silicon nitride interface with varying silicon substrate thicknesses. Visualization indicates that the crystalline silicon amorphizes upon impact. The objective of the present study is to determine where the boundary between amorphous and crystalline silicon occurrs. In the analysis, the silicon substrate is separated into sixty layers and for each layer the average z displacement is determined. Our results show that the boundary between amorphous and crystalline silicon occurs between layers 20 and 22 for an impactor traveling at 5 km/s. This corresponds to a depth of approximately 32 Angstroms into the silicon. More detailed analyses reveals that the z displacement is noticeably larger for the layers that do not have a silicon atom bonded beneath them compared to the ones that do. [Preview Abstract] |
Monday, March 16, 2009 1:15PM - 1:27PM |
B13.00011: $^{14}$N (p,p) Scattering with the KN Van de Graff Accelerator Stephanie Lyons, Michael Wiescher The $^{14}$N (p,p) scattering experiment was performed with the 4 MV KN Van de Graff Accelerator at the Nuclear Structure Laboratory at the University of Notre Dame. The KN experienced many problems throughout the experiment requiring several belt changes, a change of the drive motor bearings, and a resistor check. The first run of data was converted to cross-sections, and normalized to 30\r{ }, which was assumed to be completely Rutherford. Resonances were found at 1.06, 1.55, 1.74, 1.80, 2.34, and 2.47 MeV. These values correlated with previous work done. Further experimentation will be required to clarify the resonances and verify that the scattering at 30\r{ } is completely Rutherford. [Preview Abstract] |
Monday, March 16, 2009 1:27PM - 1:39PM |
B13.00012: Orientation of the adiabatic demagnetization refrigerator in the Micro-X sounding rocket Kaitlyn Yoha, Tarek Saab, Tylor Whitmer, Patrick Wikus The Micro-X sounding rocket is a small rocket equipped with an X-ray telescope and will be launched in 2011. For the telescope to function properly, the adiabatic demagnetization refrigerator (ADR) must be aligned with the optics of the X-ray detectors. During the mission, the ADR will move, thus causing errors. A testing prototype was designed and constructed in the lab to simulate the movement the ADR will experience in flight. This method will monitor the orientation of the ADR relative to the detectors, and allow us to counter the resulting measurement errors. [Preview Abstract] |
Monday, March 16, 2009 1:39PM - 1:51PM |
B13.00013: Use of Multivariate Analysis Techniques to Form a Comparison of Mars Odyssey Gamma Ray Elemental Data to Neutron Data Paul Abbazia The Lunar Reconnaissance Orbiter's (LRO) primary mission is exploration. Additional science falls to a secondary focus. LRO does not possess a gamma ray spectrometer, but it has the collimated neutron detector LEND (Lunar Exploration Neutron Detector). It is of interest to determine as much as possible about the moon's elemental composition using LEND. To do so, data from a similar instrument on Mars Odyssey, HEND (High Energy Neutron Detector), was compared to data from Mars Odyssey's gamma ray spectrometer (GRS). Elemental maps were previously derived from the GRS data, and a relation to HEND would allow for LEND to fulfill this role on LRO. Toward this purpose, different multivariate analysis techniques were used to compare GRS and HEND data, including Principal Components Analysis (PCA), K-means clustering, and Pearson product-moment correlation. Results indicate that two elements well known to effect neutron counts, hydrogen and iron, can be identified by these techniques. Further analysis may find additional relations, which would have benefits to the fields of geochemistry and neutron spectroscopy. [Preview Abstract] |
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