Physics Majors' Senior Research Project Abstracts
Nuclear Effects in 3He Structure Functions and Asymmetries
Jacob Ethier, Stetson University, and Wally Melnitchouk, Thomas Jefferson National Accelerator Facility
In polarized electron-nucleon scattering, spin structure functions (SSFs) give information about quark spin contributions to the total nucleon spin. Since free neutron targets are nonexistent, nuclei such as 3He (two protons and one neutron) and deuterium (one proton and one neutron) are commonly used as effective neutron targets to gather SF data. The aim of this work was to study theoretical models of 3He SSFs and polarization asymmetries (ratios of polarized to unpolarized SFs) that account for bound nucleon effects so that neutron information can be reliably extracted from nuclear data. The 3He SSFs and asymmetries can be calculated by smearing the proton and neutron SSFs with the light-cone momentum distributions of the nucleons in the nucleus. The full calculations of the 3He SSFs and asymmetries reveal a distinct difference in resonance structure compared to the free nucleon SSFs.
A Dynamic Computational Study of the Role of Ion Channels in a Neuron
Eric Hall, Dr. Danielle Morel, Stetson University
Neurons are cells in the nervous system that exchange information across connections, called synapses, using electrical signals that are formed by a voltage (a charge imbalance) across the cell membrane. This voltage changes as ion channels (specialized protein pores) selectively allow ions (charged particles) to flow across the membrane. The neuron adds together the individual signals received in a process called synaptic integration. It is expected that as synaptic input is added to a neuron, the effect of each additional signal on the integration process will be less than the previous input. Instead, linear synaptic integration has been observed at times, whereby additional synaptic signals have the same effect as the previous input. Linear integration uses specialized ion channels to modify the strength of these synaptic signals. This research studies the role of three types of ion channels in the context of linear synaptic integration. We constructed a computational model of a neuron, which we used to study the channels individually and in combinations to identify the conditions required for linearization.
Determining the Critical Temperature of a YBCO Superconductor using AC Susceptibility Measurements
Nicholas Puerling, Dr. Kevin Riggs, Stetson University
The critical temperature for a superconductor can be determined by using AC susceptibility measurements. Using an AC susceptometer in combination with a lock-in amplifier, it is possible to measure the in-phase and out-of-phase components as a function of temperature. By cooling the YBCO superconductor using liquid nitrogen, I was able to plot the transition to superconductivity.
Analyzing Reverberation Times in The Rinker Environmental Learning Center at Stetson University
Brett C. Abraham, Dr. Kevin Riggs, Stetson University
This research analyzes reverberation times and how they can be reduced by certain materials. The goal was to provide an analysis of and solution to the high reverberation times of a classroom. The results showed that reverberation time could be reduced significantly by covering a portion of the walls with acoustical tile
Calculating the Local Acceleration Due to Gravity Using a Pendulum
Robert Erdman, Dr. George Glander, Stetson University
The main goal for my research is to identify the local acceleration due to gravity using a tried and true method of employing a pendulum in its simplest form. Starting with a simple pendulum, then increasing the complexity to include two rotary motion sensors, increasing the resolution of the sine wave, while also using a power series for the period equation eliminating the small angle approximation, I am able to achieve a decent figure for the local acceleration due to gravity. This figure can and is used in determining the local value of "g" to get indirect measurements on the local geological conditions under the surface soil.
Roemer's Speed of Light
Amanda Hartlieb,Dr. Kevin Riggs, Stetson University
We measured the speed of light in the same way Ole Roemer did in the 1600's. Using a telescope, we observed Jupiter's moon, Io, eclipsed at one part of the year when Jupiter was close to Earth and once again when Jupiter was farther from Earth. There is a difference in time between the actual time Io eclipses and the time obtained from calculating the periods of Io. Using this time difference and the distance difference between the two times, we used the equation, v=d/t. This gave us results within 3% of the accepted value of the speed of light.
Building an Optical Pyrometer that Calculates Blackbody Temperatures Using the Intensity of Two Infrared Wavelengths
Stephanie Lengemann, Dr. George Glander, Stetson University
An optical pyrometer is a temperature-measuring device that uses electronic and optical components for non-contact temperature measurements. Devices such as these are highly desired in industrial and research settings when temperatures cannot be measured with thermocouples or other probe-like sensors. Examples include objects that are moving or inside a vacuum. This project focused on the design and initial construction of an infrared optical pyrometer that will eventually be used to measure the temperature of a sample of silicon inside a vacuum chamber. By measuring the intensities of two infrared wavelengths emitted from the sample, blackbody laws can be used to find the temperature of the sample. Our optical pyrometer was constructed of two converging lenses, a photodiode with the appropriate electronics for signal amplification, and two narrow band-pass filters, 980nm and 1550nm. Initial tests of the pyrometer were performed by using it to measure the temperature of a glowing filament inside of a custom blackbody oven. Another optical pyrometer, which uses a disappearing filament method, was used to determine the accuracy of our constructed pyrometer. At this time the constructed optical pyrometer is measuring temperatures within 9.5% of those measured by the disappearing filament pyrometer for temperatures near 900 °C (1173 K).
Determining the Hall coefficient of gold thin films
Christopher Rowley, Dr. Kevin Riggs, Stetson University
Gold films were grown on a microscope slide using a sputtering chamber. Argon gas ions were bombarded against a gold target to lay the films. A current ran through copper wires attached to the film while the film was exposed to a magnetic field. The Hall voltage induced was measured through copper wires attached to tabs perpendicular to the current. The thickness of the film, t, was determined using the total time that gold particles were laid on the surface. The thickness of the film was 293.8 nm. Values for the Hall voltage and magnetic field were also used to calculate the Hall coefficient, RH, of 7.49 x 10-11 m3/C. This value was 4.0% away from the accepted Hall coefficient for gold, RH, of 7.2 x 10-11 m3/C.
Using a Toy Monte Carlo Simulation to Accurately Measure the Distance between a Neutral Pion and a Cesium Iodine Detector
Angela Steinmann, Stetson University; Dr. Myron Campbell, University of Michigan, Dr. Danielle Morel, Stetson University
The K0TO collaboration is an ongoing high-energy physics experiment located in Tokai Japan. Its main experimental goal is to detect rare meson decay modes, specifically that of neutral K-mesons (kaons). Mesons are atomic particles composed of a quark and an anti-quark. If observed, this rare kaon decay will help us understand the predominance of matter over antimatter in the Universe. Kaons are highly unstable and typically decay into neutral Pi-mesons (pions). In turn, these pions immediately decay into a pair of photons, which then travel toward a cesium iodine detector. However, not all photons will reach the detector, due to the physical limitations of the detector's size and the specific location of the decays. While participating in the University of Michigan's REU summer program, I created a simplified Monte Carlo, implemented in Mathematica. This program was used to calculate the optimal distance between the detector and the location at which the pion de-Senior Research Projectscays into two photons. Ultimately, a million random pion positions were generated within a ten-meter range of the detector. As the simulation varied the pion's location, the final position of each photon was calculated. It was found that the pair of photons had the best probability, 78.5%, of hitting the crystals when the pion decayed around 1.05 meters from the detector. By understanding the most probable decay location, the K0TO collaboration will use this result to fine-tune the alignment of the detector apparatus.
A Study of the Frequency Doubling Conversion Efficiency of the Non-Linear Optical Crystal KTP
Sommer White, Dr. Kevin Riggs, Stetson University
Potassium titanyl phosphate or KTP is a non-linear material that is ideal for frequency doubling electromagnetic waves. Many applications favor KTP over the traditional KDP (Potassium Dihydrogen Phosphate) due to it's increased efficiency of conversion from the 1064 nm wavelength to the 532 nm wavelength. This can be seen in the manufacture of green laser pointers. The most cost-effective and efficient way to manufacture a green laser pointer without using the costly green laser diode is to use a 1064nm Nd: Yag Neodymium: Yttrium Aluminum Garnet laser in conjunction with a KTP crystal to achieve a 532nm wavelength. In this study we examined both polarized and non-polarized variable intensity incident light, measuring the ratio of 532nm intensity compared to that of the 1064nm input wave. We expected to find that the relative intensity of the frequency-doubled wave was directly proportional to that of the original wave but received surprising results upon close analysis.
The Role of Voltage-Dependent Dendritic Ion Channels in Linear Synaptic Integration
Igor Domladis, Dr. Danielle Morel, Stetson University
Drag Coefficient (CD) of a Model Rocket
Daniel Yount, Dr. Kevin Riggs, Stetson University
Spectrally resolved white light interferometry as an absolute measurement device
Andrea Belanger, Dr. Robert C. Youngquist, NASA Undergraduate Student Research Program
Impressive absolute distance measurement can be achieved using spectrally resolved white light interferometry (SRWI) and a high-resolution spectrometer. We have demonstrated such a device that can measure distances over a range of 150 microns with a resolution of less than 0.1 nm. However, this performance requires a spectrometer calibrated to at least the same resolution over the entire operational spectral band, which is not readily achievable, but there is a way out. As long as one wavelength assignment in the spectrometer is correct, the distance measurement process can be inverted to yield a spectrometer calibration technique. Wavelength assignment to better than 0.1 nm has been demonstrated across broad spectral regions, a significant improvement to the current process of using a few known wavelengths and polynomial fits.
Experiments in Two-Dimensional Electric Impedance Tomography for Applications in Breast Cancer Imaging
Timothy Holifield, Dr. George Glander, Stetson University
This research project seeks to begin the process of contributing new hardware concepts to the broader study of Electric Impedance Tomography (EIT). Implementing design aspects from several leading researchers, and utilizing algorithms developed by graduate research labs, we have studied two-dimensional EIT in an effort to understand this imaging technique and to study how various parameters affect data collection. We have developed an experimental setup that can be used for further study of EIT, while issues involving image reconstruction remain to be resolved.
Enhanced Substrate Control for Glancing Angle Deposition
Brian Bell, University of Nebraska, Lincoln, REU
Glancing angle deposition (GLAD) is a self-shadowing growth technique that is employed to deposit films of self-assembled nanostructures, so-called sculptured thin films (STFs), onto a substrate. In order to achieve chiral growth of the nanostructures, GLAD requires precise substrate control. The following is the design and implementation of a programming interface that allows the growth of STFs composed of columnar nanowires, chevrons, nano screws, and multilayered combinations thereof. The speed, direction, and axis of the rotation determine the structure which is grown on the substrate. The implemented user interface and program structures allow manual and automated control of motorized substrate rotation in order to grow sculptured thin films for future research. In particular, the automated control of growth process parameters will enable the development of STFs for optical, mechanical, and biological applications.
Installation of Limiting Switches on the X-Ray Diffraction Apparatus
Daniel Lane, George Glander, Stetson University
The x-ray diffraction lab utilizes a Geiger-Muller x-ray detection tube mounted on the end of a rotating arm, which sweeps through an angle of 95 degrees to detect x-rays that have been reflected off of a crystalline sample. This is used to learn about the molecular structure of the desired sample. The large sweep of the detection arm occurs close to the operational limits of the device. Due to the nature of the lab, this process takes about an hour, so it is not uncommon to have unobservant users let the detection arm sweep out of bounds. Should this happen recalibration would be necessary and damage could possibly be incurred. The goal of my project was to incorporate fail-safes at the limits of operation. This required modifying both the LabView program, which controls the stepper motor for the detector arm and the actual hardware on the device. Microswitches were installed at the operational limits of the device as to not decrease the functional range for scanning. A subroutine was then developed which checked the states of these switches before moving the detection arm and safely moved the detection arm away from the switch in the event that one of these switches was activated. This subroutine was then implemented into the applications required to operate the x-ray diffraction lab and were successfully tested.
Photoionization of the excited sodium atom from the 2p subshell
Christian Pecora, University of Central Florida REU
In this study, the theoretical foundation for an experiment that replicated the photoionization of the excited state sodium atom in the stellar atmosphere was attempted. The experimental cross-section calculated was to be compared with the theoretical cross-section that was expected through the course of the study. The initial wavefunctions for the excited sodium atom and its six ionic states were calculated using a Unix-based program with the wavefunction approximation algorithm called the Hartree-Fock method. The final wavefunction states could not yet be calculated because of convergence errors in the program. This precluded calculation of the theoretical cross-section and comparison with the experimental. Future work involves solving the convergence problem and calculating the final wavefunctions as well as computing and comparing the cross-sections.
Studying the Efficiency of Stirling Engines
Jonathan Peterson, Kevin Riggs, Stetson University
In an attempt to contribute to the increasingly important search for alternative sources of energy from fossil fuels, I did a study on the efficiency of Stirling engines. Using a single-cylinder Stirling engine, I used sensors connected to a computer with LoggerPro software to make measurements of the pressure, piston location, and temperature of the engine while it was operating. I was able to enter these values into specific formulas in order to calculate the efficiency of the engine. Then, using merely a combination of duck tape, Styrofoam cups, and aluminum foil, I was able to improve the efficiency of the engine by a factor of three. These results show that improving the efficiency of these engines is a very practical goal, and that the focus should be on insulation techniques.
Synchronization of Chaotically Oscillating Traveling Wave Tube Amplifiers
Michelle Adan, John Rodgers, IREAP, University of Maryland
Increased dependence upon traveling wave tubes (TWT) for communications systems has stimulated a demand for higher spectral efficiency. This efficiency is possible with chaotic signaling, which is more robust with respect to noise than linear modulation. Existing systems utilize TWT operation in the linear regime. However, close to saturation levels, the signal response shifts from the linear regime into nonlinearity, and then chaos. Given a system of two coupled TWTs, the receiving TWT can synchronize with the chaotic transmitter to amplify the signal with little distortion. We will reproduce such a system with two TWTs of identical central frequency and maximum power to determine what strength of coupling is necessary between the two tubes for synchronization.(This work was done with the support of an NSF-REU summer internship at the University of Maryland).
Construction and Analysis of a Corona Discharge Motor
Alfonso Ramirez, Dr. Kevin Riggs, Stetson University
The senior research project involved the construction and analysis of a standard electrostatic corona motor. The corona motor that was built consists of three cylinders, situated side by side, and separated from one another by approximately 1mm. The center cylinder is made up of a hollow 4" Polyvinyl chloride pipe that has the inside lined with a thin aluminum sheet was mounted on a rotating shaft. The two cylinders on either side of the rotor consist of aluminum and make up the stator of the motor. A Van de Graaff generator, which runs on a motor-driven belt, was used to charge one of the aluminum cylinders to a high voltage while the other cylinder was grounded. The output power of the motor was measured experimentally by determining the mechanical work necessary to lift an object over a certain distance in a given time. The input power was considered to be the power provided by the power supply, which powered the motor for the Van de Graaff generator. An approximate value for the efficiency,ç, was then calculated by dividing the output power from the input power of the motor. Various other methods of determining a numerical value for the efficiency of this corona motor are presented and compared. A discussion on how the corona motor works is also presented.
Using a Genetic Algorithm to Simulate Hydrocarbon and Hydrosilicon Structures
Charles Rareshide, Yongxin Yao, Dr. Cai-Zhuang Wang, Dr. Kai Ming Ho, Iowa State University
A geometric genetic algorithm is used to simulate hydrocarbon and hydrosilicon clusters. The algorithm produces possible candidates for hydrocarbons using Brenner's empirical potential and the Hansen-Vogel potential for the hydro silicons. The candidates are then mated to form new candidates. The candidate pool is updated and relaxed. This technique is repeated until no new structures with lower energies are produced within a few hundred iterations. The total energies of the structures are calculating using MP2 and DFT methods. The calculated energies for the hydrocarbons are then compared to the experimental formation enthalpies found in the NIST database. The genetic algorithm is found to be an efficient optimization tool for finding low-energy structures. MP2 calculations for the hydrocarbons appear to correlate more with the experimental formation enthalpies than the DFT energy calculations.
Investigative Imaging of Internal Structures on Escherichia Coli
Darash Desai, Dr. Kevin Riggs, Stetson University
An investigation was initiated into the structure of membrane-bound proteins involved with oxidative phosphorylation in Escherichia coli. An Atomic Force Microscope was used to first conduct surface scans of bacteria in a bacterial colony. Positive results resolving these bacteria provided strong support for continuing the investigation into the imaging of protein clusters on the surface of a bacterium, and finally, on the surface of the inner membranes that house the proteins involved with oxidative phosphorylation.
Measuring the Critical Temperature of YBCO with a LabVIEW-controlled Cryostat.
Bryan Tholl, Dr. George George, Stetson University
Superconductivity is a phenomenon observed is some materials at very low temperatures ranging from nearly 0 Kelvin to the highest known at almost 140 Kelvin where the material conducts electricity with zero resistance. The temperature at which a material becomes superconducting is known as the critical temperature. This project focused on measuring the critical temperature of the superconductor YBCO with a computer-controlled cryostat. A computer program called LabVIEW was used to take measurements of the resistance, the temperature, and to control heating coils wrapped around the cryostat to regulate the temperature of the YBCO contained within. The cryostat was lowered into a dewar of liquid nitrogen to cool the YBCO below its critical temperature. To find the critical temperature the YBCO was heated until it transitioned from its superconducting state.
The Effects of Magnetic Fields on 90° Scattered Polarization at Sodium D1 and D2 Wavelengths
Brandon Marsell, Stetson University, DeLand Fl.; Dr. Steven Tomczyk, High Altitude Observatory, Boulder, CO.
In solar research, much information about the sun can be gathered from the polarization state of light radiating from it. By isolating the sodium D1 and D2 wavelengths and analyzing their polarization state, one can detect magnetic fields in the lower limb of the sun . Using the four stokes parameters I,Q,U,V it is possible to fully describe the polarization state of light at the sodium D1 and D2 wavelengths. A laboratory study was conducted to relate Stokes polarization measurements at these wavelengths to magnetic fields.
The experiment consists of a glass cell containing sodium gas embedded in a pair of Helmholtz coils capable of producing around 200 Gauss. The cell is then illuminated with unpolarized light and a polarimeter is used to measure the polarization state of the light scattered at 90° since this is the angle of light polarized at the solar limb. The setup allows for the measurement of the polarization state as a function of the magnetic field.
The results of the experiment reaffirmed the theoretical prediction of zero Stokes U and V polarization and an increase in Stokes Q polarization at a 0° increasing magnetic field for the D2 wavelength .
 Trujillo Bueno et al., Appl. JL. L53, 566 (2002).
Brandon won the R. S. Jin Award (best oral presentation) at the Zone 6 SPS meeting on February 17, 2007 at the Florida Institute of Technology. The best of 16 presenters, Brandon even beat out five graduate students!
Imaging the Magnetic Domains of Magnetotactic Bacteria Using Magnetic Force Microscopy
Justin Black, Dr. Kevin Riggs, Stetson University
Unlike human beings, many organisms are sensitive to the earth's magnetic field. Magnetotactic bacteria, in particular, use this magnetic field to navigate to a vertical zone within bodies of water that contain a balance of essential nutrients. These bacteria develop a ferromagnetic pellet which is used like a compass needle. The goal of this research was to find and image the magnetic properties of this specific type of bacteria using a magnetic force microscope. Site selection was based on accessibility and water current conditions. The "fishing" device used was a strong ferromagnet secured with a length of rope to a wooden extension. The magnet was covered with a thin plastic film. The goal of this configuration was to submerge the magnet, attract magnetotactic bacteria based on their magnetic properties, and be able to transfer the sample for imaging in a practical way.
To locate biological candidates on the slides, atomic force microscopy was used. Biological features appeared fuzzier than the residual sediment and sand. This is due to the soft nature of the features interpreted by intermittent contact imaging. Magnetic force microscopy was then performed to distinguish between magnetic and non-magnetic bacteria. In particular, dipole behavior was expected of a bacterium moving by magnetotaxis. Although the dipole behavior of their ferromagnetic components was not successfully imaged, the method of topographical scanning located and imaged some biological features.
LIGO Detection Efficiency Studies in Searches for Gravitational Waves from Binary Neutron Star Inspirals
Sarah Caudill, Stetson University; Peter Shawhan and Duncan Brown, LIGO, CalTech, Pasadena, CA
Gravitational waves are one prediction of Albert Einstein's general theory of relativity. The Hulse-Taylor binary pulsar offers indirect evidence for these waves but direct tests have not been possible until recently. Scientists at several sites across the globe, including LIGO (Laser Interferometer Gravitational-Wave Observatory) are currently utilizing optical interferometry in an attempt to detect gravitational waves. Several astrophysical events including binary neutron star inspirals may act as sources of gravitational waves by creating ripples in spacetime. Binary neutron star inspiral waveforms are described by only two parameters, the masses of the two stars (neglecting spin). Detecting gravitational wave signals from inspiraling binary neutron stars thus requires a two-dimensional bank of theoretical waveform templates for matched filtering. The method of template bank construction was analyzed from a study of the LIGO algorithm library (LAL). The goal of the bank construction algorithm is to ensure that any signal in the region of interest of the parameter space closely matches one of the templates without wasting CPU time. The accuracy of the expected 0.97 minimal match value was reviewed using ellipses of constant match drawn around templates in both the currently used square bank and a promising new hexagonal bank. The more efficient hexagonal bank layout system will soon be implemented in place of the square system. Further research will involve the generalization of the mismatch measurements to the higher dimensional parameter spaces (including spin) used for binary black hole searches.
Building a Computer Controlled Liquid Nitrogen Cryostat
Danielle Mollman, Dr. George Glander, Stetson University
Many physical properties depend on temperature. While experimentation at extremely low temperatures can be beneficial because of uncharacteristic results, experiments can often be very difficult to execute and manage due to the difficulty in controlling the temperature. The purpose of the research was to create a computer-controlled liquid nitrogen cryostat. A cryostat is a small chamber capable of regulating its internal temperature and the temperature's rate of change when used in conjunction with liquid nitrogen. The chamber is a thin aluminum cylinder of length 7 cm, diameter 5 cm, and minimal thickness, with the capability of having an aluminum cold finger extending down from the bottom of the chamber. A wire heater with a 25 W maximum is wrapped circumferentially around the outside of the chamber, allowing for temperature regulation. The cryostat is completely managed by a computer using Labview. The purpose of the Labview program accompanying the cryostat is for the chamber to reach a desired set point temperature internally. A proportional integrating differentiator (PID) was used in the Labview program to help minimize temperature oscillation. The PID controls the heater voltage by constantly monitoring the difference between the chamber's actual temperature and the set point temperature, using the value to determine an appropriate proportional output voltage. The cryostat will be greatly beneficial in future research because it will help eliminate errors and difficulty when experimenting at low temperatures.
Design of a Force Sensor using Strain Gages to measure the Elastic Modulus of a fibroblast-seeded Scaffold
Renee Dickinson, Stetson University; Joshi and Webb, Clemson University, Clemson, South Carolina
Speckle Pattern Averaging in Electronic Speckle Pattern Interferometry
W. Langston, Dr. Kevin Riggs, Stetson University
Development of a Third Generation Piezoelectric Contact Sensor with Applications to Manatee Protection Systems and Remotely Operated Vehicles.
Dan Carlson, Stetson University; Larry Taylor at Harbor Branch Oceanographic Institution
Studying the Thermodynamics of Vortex Tubes
Nick Frost, Dr. Tom Lick, Stetson University
Analysis of Magnetic Structures via Magnetic Force Microscopy
Jon Gosnell, Dr. Kevin Riggs, Stetson University
Setting Up the Small Radio Telescope (SRT) and the Galactic Rotation Experiment
Ari Litwin, Dr. Kevin Riggs, Dr. Anthony Jusick, Stetson University
An Explication of the Construction of a Laser Doppler Velocimeter, for the Purpose of Examining the Onset of Turbulence in Fluids
R. Adam Pridemore, Dr. George Glander, Stetson University
Thernak Stability of Ti on Al-110 Single Crystal Surface
S. Paul Stuck, Stetson University; work done at Ion Beam Lab, Montana State University