Undergraduate Honors Program - Physics and Astronomy Department
Permanent URI for this community
The Honors Program requires a high level of accomplishment in a rigorous program of course work and culminates in research work which is presented as a senior thesis. Note particularly the requirements of independent study or thesis credit hours and the grade point average for a) all course work, b) course work in the major, and c) course work taken while a candidate for honors. Preparation during the junior year for the thesis project is strongly encouraged, but actual application for candidacy in the honors program usually is done promptly at the start of the senior year.
| Department Location: | 6301 Stevenson Center Vanderbilt University Nashville, TN 37240 |
| Mailing Address: | Vanderbilt University 6301 Stevenson Center VU Station B #351807 Nashville, TN 37235 |
| Phone: | 615-322-2828 |
| Fax: | 615-343-7263 |
| Email: | Physics-Astronomy@vanderbilt.edu |
| Website: | Department of Physics & Astronomy |
Browse
Browsing Undergraduate Honors Program - Physics and Astronomy Department by Issue Date
Now showing 1 - 20 of 50
Results Per Page
Sort Options
Item Exploring the Local Association : a nearby, young kinematic stream of stars in the solar neighborhood(Vanderbilt University. Dept. of Physics & Astronomy, 2008) Saling, Chris; James, David J.During the course of my Honors Research Project, I worked with Dr. David James to determine whether a group of target stars are members of the Local Association. I did this by reducing spectroscopic data, taken by Dr. James, in order to determine the radial velocity and lithium contents of the stars. Using the radial velocity measurements, the kinematics of each star was then defined by determining their U,V,W space motions. Lithium measurements were used to establish star youth and provide further evidence to support membership of the Local Association.Item Progress towards a quantum dot photovoltaic : nanocrystal deposition on structured titanium dioxide nanotubes(Vanderbilt University. Dept. of Physics & Astronomy, 2008-04) Emmett, Kevin; Rosenthal, Sandra J.While this project did not successfully produce a working photovoltaic device, significant progress has been made in the individual components of the system. This thesis describes two of those components: fabrication of an ordered TiO2 thin film as electron conducting layer, and deposition of nanocrystals onto the TiO2surface. The anodized titanium nanotubes are a significant improvement over the earlier template technique. Additionally, electrophoretic deposition presents a novel approach to nanocrystal deposition techniques and is a promising alternative to the current chemical linking procedure. However, significant new approaches to imaging the deposited nanocrystals must be developed to verify surface coverage by these deposition techniques, particularly due to the highly ordered structure of the TiO2 thin films. Future work will be directed at completing the solar cell device by depositing a hole conducting layer on top of the nanotube array. Nanocrystal-sensitized solar cells may soon prove to be viable alternative to silicon photovoltaics.Item Reflection and rotation for three dimensional microscopy of live cells(Vanderbilt University. Dept. of Physics & Astronomy, 2008-04-18) Wright, Charlie; Wikswo, John PeterConfocal scanning laser microscopy and multiphoton microscopy provide 3D data from biological specimens, but with limited z-axis precision. Multiple microscale mirrors can be used to obtain more accurate 3D data on living cells while using classical widefield microscopy. Etched silicon wells coated with aluminum were used to obtain 3D images of budding yeast cells, with information along the z-axis provided by reflections from the angled sides of the well. To supplement measurements obtained with this method, work was also conducted on a system to allow for rotation of a cell attached to a pulled glass tip. Images of a yeast cell obtained from either method can be fit to a simple 3D surface due to the cell's roughly spheroidal shape, which should provide accurate measurements of the volume of an individual budding yeast cell as it progresses through the cell cycle.Item Number density profiles of galaxy groups and clusters in the SDSS(Vanderbilt University. Dept. of Physics and Astronomy, 2008-04-20) Norris, Jackson M.; Berlind, AndreasWe use projected number density profiles of galaxy groups to investigate the relationship between galaxy group structure and dark matter structure within halos. We primarily study a specific model of how galaxies populate dark matter halos by comparing the number density profiles of galaxy groups from the Sloan Digital Sky Survey with number density profiles of galaxy groups taken from dark matter halo simulations. We also investigate the dependence of galaxy locations within galaxy groups on luminosity and color.Item Influence of patient size on dose to female breast tissue during routine computed tomography scans(Vanderbilt University. Dept. of Physics & Astronomy, 2008-04-21) Scully, Peter C.; Stabin, MichaelMonte Carlo methods are well suited to the evaluation of radiation transport phenomena. The scalable phantoms employed in this project permitted rapid creation of three models of similar geometry, but different body habitus. It is difficult at this point to draw any conclusions about the relationship between patient size and radiation dose to breast tissue during CT scans of the chest. However, the results of DeMarco et al. suggest that we may find a more complicated relationship between breast size and breast dose than we anticipated. Whatever the relationship, it is important that physicians and radiologists realize how dose delivered by CT varies with breast size, so that an effective balance of risks and benefits may be obtained for all patients in diagnostic CT imaging.Item Structure function analysis of blazars AP Librae and 3c279(Vanderbilt University. Dept. of Physics & Astronomy, 2008-04-27) Jensen, Anders A.; Knop, Robert A.Blazars AP Librae and 3c279 are analyzed for microvariability using a technique known as structure function analysis. AP Librae was observed in April of 2005 and 3c279 was observed in April of 2007. The data for AP Librae was previously reduced by Andrew Collazzi and the author reduced the data for 3c279. Both sets of data were reduced using Robert Knop's data reduction program. The author ran structure function analysis on both sets of data. Structure function analysis is a statistical analysis run on data that is suppose to nd timescales of variability, periodicity, and the noise type of data. Previous analysis of AP Librae confirmed mircrovariability, which also shows up in the structure function of AP Librae. Blazar 3c279 was much quieter than AP Librae and showed no microvariability durning any of the nights.Item Micro Programmable Object Navigation Gadget (micro-PONG) for Studying Electroosmotic Flow in PDMS Microchannel(Vanderbilt University. Dept. of Physics and Astronomy, 2009-04-20) Rohrman, Brittany Ann; Wikswo, John PeterPrecise control of fluid delivery in analytical devices may be achieved by harnessing electroosmotic flow (EOF) in oxidized poly(dimethylsiloxane) microfluidic channels fabricated via soft lithography. However, the magnitude of this flow depends on a number of parameters, including the geometry and surface chemistry of the channel walls, and is known to attenuate over time. In order to characterize these parameters and calibrate the magnitude of EOF in our devices, we have developed a versatile automated control and measurement system called micro-PONG (Micro Programmable Object Navigation Gadget). The system detects, controls, and measures the movement of polystyrene beads caused by EOF in the channel. The micro-PONG system consists of a LabView program, a DAQ board, an external voltage switching circuit, and a camera. A computer algorithm reverses the direction of the EOF each time the bead enters one of two user-specified "goalpost" areas, thus keeping the bead trapped and moving back and forth between the goalposts (similar to a game of ping pong) for extended periods of time. From the recorded motion of the bead, the three-dimensional velocity profile of the fluid in the channel may be estimated using a novel ImageJ macro for determining motion in three dimensions. This analysis may then be used to determine the magnitude of the EOF, inertia, and response time of the system as well as the time-dependent effects of PDMS surface properties on EOF. The micro-PONG system may also be useful for other purposes that require the automated manipulation of particles or cells.Item Blazar Microvariations(Vanderbilt University. Dept. of Physics and Astronomy, 2009-04-20) Pittman, Cameron W.; Professor Robert KnopIn November 2006, the authors collected data on blazars PKS 0537-441, PKS 0447-439, and PKS 0208-5121 from the Cerra Tololo Inter-American Observatory in Chile. All three blazars are tested for microvariability, first by comparing relative magnitudes against unvarying stars, then through power spectrum analysis. The authors used GNU Scientific Library tools for the Fourier transforms needed for power spectrum analysis. Fourier transforms break down data into series of periodic functions. Running power spectra quantitatively illuminate periodicity and variability in data. The authors tested power spectra by using well-defined functions to better understand power spectra analysis. Through light curve analysis and power spectra analysis, the authors found PKS 0537-441 showed microvariability, PKS 0208-512 most likely did not show microvariability, and PKS 0447-439 did not show microvariability.Item Measurement of Energy Spectrum of Electrons Field-Emitted from Diamond Field-Emitter Arrays(Vanderbilt University. Dept. of Physics and Astronomy, 2009-04-20) Stewart, Christopher L.; Brau, Charles A., 1938-A retarding mesh analyzer was used to measure the electron energy spectrum field emitted from a single tip of a Diamond Field Emitter Array. The emission was dominated by adsorbed gas atoms and molecules on the surface which were both spatially and temporally unstable. As a result, the spectra taken had highly variant spectral features and there was an order of magnitude span in the emitted current. The spectrum from a clean surface roughly obeyed the thermal field emission model and was consistent with reported spectra from a nitrogen-doped, diamond-like carbon film.Item Data Logistics and the CMS Analysis Model(Vanderbilt University. Dept. of Physics and Astronomy, 2009-04-20) Managan, Julie E.The Compact Muon Solenoid Experiment (CMS) at the Large Hadron Collider (LHC) at CERN has brilliant prospects for uncovering new information about the physical structure of our universe. Soon physicists around the world will participate together in analyzing CMS data in search of new physics phenomena and the Higgs Boson. However, they face a significant problem: with 5 Petabytes of data needing distribution each year, how will physicists get the data they need? How and where will they be able to analyze it? Computing resources and scientists are scattered around the world, while CMS data exists in localized chunks. The CMS computing model only allows analysis of locally stored data, "tethering" analysis to storage. The Vanderbilt CMS team is actively working to solve this problem with the Research and Education Data Depot Network (REDDnet), a program run by Vanderbilt's Advanced Computing Center for Research and Education (ACCRE). I participated in this effort by testing data transfers into REDDnet via the gridFTP server, a File Transfer Protocol which incorporates an LHC Computing Grid security layer. I created a test suite which helped identify and solve a large number of problems with gridFTP. Once optimized, I achieved sustained throughputs of 700-800 Megabits per second (Mbps) over a 1 Gigabit per second (Gbps) connection, with remarkably few failures. GridFTP is the gateway between REDDnet and CMS, and my tests were designed to exercise and harden this important tool. My results support other indications that the REDDnet system will be a successful solution to the limitations of data-tethering in the CMS computing model.Item A Search for Pre-Main Sequence Eclipsing Binary Stars in the Lagoon Nebula(Vanderbilt University. Dept. of Physics and Astronomy, 2009-04-20) Henderson, Calen B.; Stassun, KeivanWe report time-series CCD I-band photometry for the pre-main-sequence cluster NGC 6530, located within the Lagoon Nebula. The data were obtained with the 4Kx4K imager on the SMARTS 1.0m telescope at CTIO on 36 nights over the summers of 2005 and 2006. In total we have light curves for ~50,000 stars in an area ~1 deg2, with a sampling cadence of ~1 hour. Approximately 1,000 of these stars have been identified as bona fide members of the cluster with masses in the range 0.25-4.0 Msun, assuming a distance of 1.25 kpc to the cluster. Our goals are to measure rotation periods for these stars and to identify eclipsing binary candidates. Here we present light curves of the 223 stars in our sample found by us to be periodically variable, and we present the distribution of the stellar rotation periods derived from these light curves. We also present 16 potential eclipsing binary star systems that, through follow-up work, will provide direct measurements of the masses and radii of the stars for testing of stellar evolutionary models. This work has been supported by the National Science Foundation under Career grant AST-0349075.Item The distribution of ejected stars around a super massive black hole binary due to three-body scattering(Vanderbilt University. Dept. of Physics and Astronomy, 2010-04) Benson, Amanda; Holley-Bockelmann, KellyItem Density profiles of dark matter halos(Vanderbilt University. Dept. of Physics and Astronomy, 2010-04) Robbins, Katherine; Berlind, Andreas A., 1972-Item Investigation of Electroosmotic Flow in Various Microfluidic Structures(Vanderbilt University. Dept. of Physics and Astronomy, 2010-04) Diggins, Patrick; Wikswo, John PeterEnclosed microfluidic devices provide excellent systems for the study of biological processes such as cell-cell, paracrine, and autocrine signaling systems. By minimizing the fluid volume within the chambers, microfluidic devices diminish the dilution of secreted products which makes the detection of the secreted products a more straightforward task. A major design problem associated with the construction of microfluidic devices for biological research is the need to provide well-controlled fluidic transportation for cells, the nutrients that the cells need, and waste removal. Most precision syringe pumps which can accurately provide low flow rates are expensive and constitute a barrier to experiment design. Electroosmotic pumps could potentially provide a valuable alternative as a low volume flow rate pumping system for many types of microfluidic devices. We have developed a poly(dimethylsiloxane) (PDMS) microfluidic device that incorporates both electroosmotic flow and pressure driven flow. The device is designed to increase the relative strength of the electroosmotic flow (EOF) component of the total flow through the use of an array of small volume parallel pumping channels which provide higher passive resistance to pressure driven flow than a larger volume single-channel EOF pump. Using a novel microfluidic instrumentation device which we call the "Micro Programmable Object Navigation Gadget" (µ-PONG), we investigate how different properties and geometries of the device affect the EOF rate. In addition, we demonstrate that fluid flow driven by a small hydraulic pressure head can be completely canceled by an user initiated EOF in the pumping channels which are incorporated into a microfluidic device. The ability to modulate the flow and to create "stop flow" conditions in microfluidic devices is also important for biological research.Item Multipole mixing ratios of transitions out of high spin gamma vibrational states in neutron rich Mo, Ru isotopes(Vanderbilt University. Dept. of Physics and Astronomy, 2010-04-27) Fenker, Benjamin; Hamilton, Joseph H.Current models of nuclear structure describe nuclear states in terms of collective vibrations and rotations of a ground state. - One such quadrupole vibrational band is the gamma-band formed by vibrations of the short sides of a deformed nucleus. - When a nucleus that is in this mode decays to its ground state, the electromagnetic radiation is predicted to be entirely quadrupole in nature. - This prediction has been well documented in a wide range of nuclei. - However, a recent study of neutron rich molybdenum and ruthenium isotopes found a few gamma-band to ground-band transitions that contained almost no quadrupole radiation. - This work utilizes the Gammasphere detector array to examine the angular correlations in the de-excitations of the secondary fission fragments of 252Cf in order to make independent measurements of these results. - This work also uses the same technique to measure the multipole mixing ratios of gamma-band to ground-band transitions originating in states with spin-parity as high as 9+. - The results demonstrate that in these nuclei, electric quadrupole radiation is strongly favored in gamma to ground band transitions as has been predicted by theory.Item Finite-Element Analysis of Low-Power Laser Heating in Gold::Vanadium Dioxide Nanocomposites(Vanderbilt University. Dept. of Physics and Astronomy, 2011-04) MacQuarrie, Evan; Haglund, Richard F., Jr., 1942-Finite element modeling was performed using COMSOL Multiphysics to study the thermal dynamics of gold::vanadium dioxide (VO$_{2}$) nanocomposites. These simulations were done to understand the data from transient absorption pump probe measurements taken over the previous two years by the author. The various parameters contributing to the dynamics of the system were systematically varied within the simulation in order to understand how the various properties of the nanocomposite affect the thermodynamics of the system. It was determined that the background temperature and the optical properties of the film make the dominant contributions to the system response. The simulation was able to predict the maximum change in transmission measured in experiment fairly well but could not predict the speed at which the system responded to the pump laser. Steps to improve upon the agreement between experiment and simulation are proposed.Item Perturbation Theory for Thin Cladding Layers on Silicon Photonic Systems(Vanderbilt University. Dept. of Physics and Astronomy, 2011-04) Phare, Christopher; Weiss, Sharon M., 1977-I develop a perturbation theory for resonant frequency shifts caused by thin layer of material added to dielectric systems. This development can be used to effectively model photonic surface-sensing systems, which use this resonance shift to measure the presence of, e.g., biomolecules attached to the sensor system. Direct modeling was previously intractable due to extremely long simulation times required to account for the cladding layers. The developed theory is verified against a special-case direct simulation and by measuring the shift caused by silicon dioxide deposited on a fabricated ring-resonator sensor.Item Developing High-Brightness Electron Beam Sources for Producing Quantum Degenerate Electron Beams(Vanderbilt University. Dept. of Physics and Astronomy, 2011-04) Kohler, Jonathan; Brau, Charles A., 1938-The Pauli Exclusion Principle places a fundamental limit on the brightness of an electron beam. Developing a cathode which can reach this limit is useful for achieving maximum operation in current applications of electron beams, but also opens new areas of physics to be explored. When the phase space of the electron beam is filled to the maximum density, the electrons will experience a degeneracy pressure, similar to that which keeps a neutron star from collapsing. One promising source for a quantum degenerate beam is field emission from adsorbates on carbon nanotubes. Adsorbates have been shown to provide several orders of magnitude enhancement to emission brightness, which approaches the degeneracy limit. We have developed experiments to test various adsorbates, in order to find those which bind tightest and provide the largest enhancement in brightness. Continuing work to discover better adsorbates should soon allow for the generation of a quantum degenerate electron beam.Item Measuring Radial Velocities of Low Mass Eclipsing Binaries(Vanderbilt University. Dept. of Physics and Astronomy, 2011-04) Rattray, Rebecca; Stassun, KeivanDue to the complex nature of the spectra of low-mass M type stars, it is difficult to determine their metallicities and temperatures directly. By studying eclipsing binary pairs comprising one F, G, or K type star with an M type star, we are able to use what we know about the primary star to learn more about the secondary star. Measuring the orbital reflex motion of the primary star, together with the eclipse light curve of the M star as it transits the primary star, allows us to determine the mass, radius, temperature, and metallicity of the M star. We studied 23 low mass eclipsing binaries (EBLMs) previously discovered by SuperWASP photometry. We obtained spectra using the Cerro Tololo Inter-American Observatory (CTIO) SMARTS 1.5-meter echelle spectrograph between June 2009 and January 2011. Each EBLM target was typically observed ~8 times over this time period. The spectra were processed using standard astronomical software, and a cross-correlation method was used to measure the radial velocity of the target star at each observed epoch. Radial velocities were successfully determined for 21 of the 23 EBLM target objects. Orbital periods, radial velocity amplitudes, and eccentricities for these EBLMs could be determined from these radial velocities together with the preexisting light curves. Using these values and by assuming a mass for the primary star, we will be able to calculate the masses of the secondary M type star in each EBLM system.Item Engineering a perfusion-enabled mechanical compressor for long-duration immobilization and microscopy of cells and small organisms(Vanderbilt University. Dept. of Physics and Astronomy, 2011-04) Jiang, Liwei; Janetopoulos, ChristopherThe study of living specimens is essential to the understanding of organismal behavior. Unfortunately, a major difficulty in the study of live organisms is that many move in and out of the field of view or focal plane during microscopy. The present work seeks to combat this considerable problem by developing a mechanical microcompressor that immobilizes living cells and small organisms for long-duration optical microscopy. The device, dubbed the "Commodore Compressor," features two key innovations: (1) the integration of a perfusion system to keep the trapped specimen alive over several hours, as well as permitting the addition of chemoattractants, drugs, and other chemicals; (2) the incorporation of an optional patterned PDMS platform to improve the efficacy of immobilization in a targeted, organism-specific manner. One application of the Commodore Compressor is in monitoring the change in protein bioluminescence intensity in many trapped Saccharomyces cerevisiae cells during synchronized cell cycles. The experiment's feasibility and key techniques have been well demonstrated, although bioluminescence cannot currently be visualized. A second application involves fluorescence imaging of the neural network development of immobilized Caenorhabditis elegans over many hours. The development of new patterned PDMS platform designs, aided by the innovative use of established techniques, has driven the present work toward accomplishing the goal, but true long-term viability remains elusive. The Commodore Compressor may be directly used or easily adapted for many other specimen types and experimental scenarios.
- «
- 1 (current)
- 2
- 3
- »