# SPS Talks Fall 2003

Please email corrections to astro@sfasu.edu. Last updated on October, 5, 2003 at 1:00 AM

SPS-1
Name: James M. Hitchcock
Affiliation: Angelo State University
Address: 2601 W AVE N, San Angelo, TX 76909 USA
Phone: 325.942.2242
E-mail: jmh4gsus@hotmail.com
Title: Attending the 2003 International Conference for Physics Students
Authors: James M. Hitchcock
Description of Paper for Session Arrangement: Each year, the Society of Physics Students (SPS) sends two United States representatives to the International Association of Physics Students (IAPS) international physics students conference. Students who are chosen to receive the Outstanding Student Award for Undergraduate Research are invited to present at the conference, with travel funded by the American Institute of Physics. Results of our work on the non-linear optical effects of InGaAs quantum well luminescence were presented at the 2003 conference, held in Odense, Denmark. This work, along with comment on the conference experience will be discussed.
Special Requirements for Paper: please provide a projector which is compatible with laptop PC (the presentation is in PowerPoint format)

SPS-2
Name: Levente Borvák
Affiliation: University of Dallas
Address: 1113 N. O'Connor Rd. #207, Irving, TX 75061 USA
Phone: 214-766-5122
E-mail: lborvak@udallas.edu
Title: DSP Neutron/Gamma Pulse-Shape Discrimination
Authors: Levente Borvák and Ákos Horváth, Eötvös Loránd University
Description of Paper for Session Arrangement: A digital signal processing (DSP) method for neutron/gamma pulse-shape discrimination (PSD) was developed for data acquired with a signal inverter circuit connected to a 500 MHz, 1 GS/s digital oscilloscope. Since no detector is perfect, and all are sensitive to more than one type of radiation, it is necessary to have a good method of PSD. The DSP procedure was written in Mathematica 4.0, and was successful in discriminating between high energy neutrons and gamma rays. The development process and discrimination ability of the DSP will be presented.
Special Requirements for Paper: Computer with a projector attached to it. (for PowerPoint) Student Competition

SPS-3
Name: Joseph Robert Gilbert
Affiliation: Tarleton State University
Address: Box T-470, Stephenville, Texas 76402 USA
Phone:254-968-9880
e-mail: st_gilbert@tarleton.edu
Title: High Sensitivity Light Element Profiling by Nuclear Reaction Analysis
Authors: J.R. Gilbert, E. Stenmark, and D.K. Marble
Description of Paper for Session Arrangement: Hydrogen and other light elements can have dramatic effects on the mechanical, electrical, and chemical properties of materials. Hydrogen is used to passivate dangling bonds in solar cells to improve efficiency while hydrogen embrittlement is a major problem in metals. The introduction of nitride layers can improve wear in gun nozzels and drilling tools and the use of nitrogen assist in sputtering has shown some beneficial effects for thin films. Unfortunately, non-destructive profiling of thin films for light impurities is often problematic especially when nanometer depth resolution and high sensitivity is required. A discussion of the advantages of Nuclear Reaction Analysis (NRA) for profiling light elements in materials and our work on developing a new state of the art detector system will be discussed. Work Supported by NSF MRI Grant #DMR-0216571
Special Requirements for Paper:

SPS-4
Name: Rachel Lee Ingley
Affiliation: Angelo State University
Address: 2601 W AVE N, San Angelo, TX 76909 USA
Phone: 325.942.2242
E-mail: staraley@yahoo.com
Title: Temperature dependence of Photoluminescence from Strained InGaAs/GaAs Quantum Wells
Authors: Rachel L. Ingley, James M. Hitchcock, Michael Williams, Toni D. Sauncy
Description of Paper for Session Arrangement: Optical techniques provide a powerful means of probing fundamental electronic properties of materials in a straightforward and non-destructive manner. Sample pairs of identical composition and well layer thickness, each grown along different crystallographic axes, [100] and [111], were studied using temperature dependent photoluminescence (PL). PL spectra for the samples indicate that the dominant optical transition occurs in the InGaAs layer, as expected by the effects of carrier confinement within the thin QW. Temperature dependence of PL spectra for both quantum wells indicates a deviation from the typical temperature dependence predicted by the Varshni equation for bulk materials. Several theoretical models for the observed temperature dependence will be discussed.
Special Requirements for Paper: The presentation will be in PowerPoint format. A projector with video compatibility for a Laptop PC will be needed.

SPS-5
Name: Federico Lopez
Affiliation: Department of Physics, University of Texas at El Paso
Address: 500 W. University Ave. Bldg. 210, El Paso, TX 79968 US
Phone: (915) 747 8422
E-mail: flopez3@utep.edu
Title: Te-rich CdS/CdTe solar cells
Authors: Federico Lopez, Javier Terrazas, Sergio Y. Rodriguez, David Zubia, William G. Durrer, Jorge Lopez
Description of Paper for Session Arrangement: Improvements in solar cell efficiency have been difficult to achieve over the past ten years. The importance of our research is to study the difference between Te-rich CdS/CdTe and normal CdS/CdTe solar cells, and also to investigate how the efficiency is affected by Te concentration. Glass/ITO/CdS/CdTe thin film solar cells were fabricated using chemical bath deposition for the CdS and Closed Space Sublimation (CSS) for the CdTe. The CdTe source used for developing the CdTe layer was Te-rich in order to create a more p-type semiconductor. Auger Electron Spectroscopy (AES), and Secondary Ion Mass Spectroscopy (SIMS) techniques were used in order to analyze the chemical composition of the interface and to determine how the composition of these films varies with depth. Te-rich type of solar cells have stronger p-n junctions; more tellurium was found to be at the interface of such junctions. Another important aspect to consider is that the grains of the Te-rich films are larger and their crystallinity is better. This would result in a lower grain barrier, which is more favorable for carrier transport.
Special Requirements for Paper:

SPS-6
Name: Louis J Antonelli
Affiliation: University of Dallas
Address: 1845 E. Northgate Dr., Irving, TX 75062 USA
Phone: 972-721-7280
E-mail: lantone@udallas.edu
Title: Frequency Study of a Fiber Grating Stabilized Diode Laser
Authors: Louis Antonelli
Description of Paper for Session Arrangement: A fiber coupled InGaAs laser was made to operate at a single frequency. This was achieved by stabilizing the temperature of the laser medium and by attaching a temperature stabilized fiber Bragg grating. The signals from two such independently stabilized lasers were temperature tuned to be within 1 MHz of each other and mixed to generate a beat frequency. By studying this beat frequency using a RF spectrum analyzer, measurements of the laser's linewidth were taken. The setup, results, and current status of the experiment will be discussed.
Special Requirements for Paper: Computer with projector. undergraduate competition

SPS-7
Name: Nazario Lopez
Affiliation: Department of Chemistry, University of Texas at El Paso
Address: PSCI BLD. RM 123, El Paso, TX 79912 United States
Phone: (915) 747 6380
E-mail: nlopez2@utep.edu
Title: Synthesis and characterization of a copper(II) cubene complex, in-situ formation of amino-imino ligand
Authors: Nazario Lopez, Thomas E. Vos, Atta M. Arif, Joel S. Miller and Juan C. Noveron*
Description of Paper for Session Arrangement: Over the years multinuclear copper(II) materials have been receiving much attention. The flexibility of the coordination sphere around Cu(II) in combination with steric and packing forces, leads to its tremendous structural diversity. Small changes in structure can have far reaching effects on the magnetic properties of these complexes. Cu(II) cubanes provide a unique opportunity for the study of factors influencing magnetic interactions of metal centers in an all-nitrogen ligand environment. Here we report a new hydroxo bridged copper cubene, with the in-situ formation of the amino-imino ligand, 2-methyl-2-amino-4-iminopentane. Crystal structure and magnetic properties are included.
Special Requirements for Paper:

SPS-8
Name: Jeremy Jarl
Affiliation: Texas State University - San Marcos
Address: 601 University Drive, San Marcos, TX 78666 USA
Phone: 512 245 2131
E-mail: jj15912@txstate.edu
Title: Density Analysis of Fluorinated Homopolymer
Authors: Jeremy Jarl, Francine Abrego, Deborah C. Koeck, Heather C. Galloway, Suresh Murugesan, Gary Beall, Chad Booth, Patrick Cassidy, Texas State University
Description of Paper for Session Arrangement: Determination of the density of some polymers is difficult due to the small quantity of the polymers available. A different method of measuring the density is necessary in order to maximize the accuracy of the measurement. This measurement will use various combinations of water and 99% pure ethanol to create liquids of specific densities. Once the densities of these liquids are calculated, we will observe a piece of the polymer in the liquid to compare it to the density of the liquid by whether it floats or not. This method allows us to measure polymer densities between 1.0 and .789 g/ml. Using this method we have determined the density of fluorinated homopolymer samples to compare to theoretical calculations.
Special Requirements for Paper:

SPS-9
Name: Stephanie Ann Wissel
Affiliation: University of Dallas
Address: 1845 E. Northgate Dr. P.O. Box 853, Irving, TX 75062 USA
Phone: 972-438-6795
e-mail: wissels@yahoo.com
Title: Skymaps for GALPROP Simulations of VHE Gamma Rays
Authors:S. A. Wissel, S. P. Swordy, S.P. Wakely
Description of Paper for Session Arrangement: The diffuse ã-ray spectrum detected by EGRET indicates an excess in the GeV energy range. Very high energy ã rays, in the TeV range, have, as of yet, not been fully characterized. Utilizing a stereoscopic Cerenkov imaging technique, the very energetic radiation imaging telescope system, VERITAS, will measure the very high energy ã-ray spectra. A numerical model of diffuse cosmic ray emission, GALPROP, was used to predict spectra in the energy range of the ã rays that will be detected by VERITAS. This paper describes the modules written for viewing the GALPROP output, particularly in the horizontal plane local to the telescope. The data were first mapped in the galactic plane, and next in the horizontal plane. Precession, nutation, and atmospheric refraction are considered in the conversion, triangulation and interpolation of the data.
Special Requirements for Paper: Undergraduate Competition Power Point Presentation--need computer and projector

SPS-10
Name: Alana J. May
Affiliation: Angelo State University
Address: 2601 W. Ave. N, San Angelo, TX 76909 USA
Phone: 325-942-2242
E-mail: alana_oliver@yahoo.com
Title: Gravitational Microlensing of NGC3314
Authors: Alana May
Description of Paper for Session Arrangement: This project used Hubble Space Telescope Data compiled over a period of 2 years to detect otherwise hidden celestial objects. Image Reduction and Analysis Facility, or IRAF, was used to evaluate the data along with a sister program, PyRAF. Single images from the HST were drizzled together using PyRAF to create a grand master image, where one can then search amgonst the data to detect for varying amplitudes of celestial objects.
Special Requirements for Paper: Projector

SPS-11
Name: Christian A Clerc
Affiliation: University of Dallas
Address: 1845 E. Northgate Dr., Irving, TX 75062 USA
Phone: 314-221-5891
E-mail: chrisclerc@yahoo.com
Title: Photometric Analysis of the Variable Star V603 Aql
Authors: Christian Clerc, Richard Olenick
Description of Paper for Session Arrangement: A SBIG ST-2000XM CCD camera was used in conjunction with a CGE 1100 telescope to take photometric images of V603 Aql, a NA+E+X cataclysmic variable star, in the Visual and Blue wavelengths. The magnitude of the star was measured using differential photometry over an eight-week observational period. The data was analyzed using Fourier and wavelet analysis to search for the cyclical brightness modulations of the star. The data and error measurements for the period of V603 Aql will be presented.
Special Requirements for Paper: Computer with projector. student competition

SPS-12
Name: Alán Dávila
Affiliation: Department of Physics, University of Texas at El Paso
Address: Leeds Ave. 4526, El Paso, Tx 79903 USA
Phone: none
E-mail: davila_alan@hotmail.com
Title: Daylight Saving Time
Authors: Alán Dávila and Jorge A. López
Description of Paper for Session Arrangement: The goal of this project is to determine how efficient the daylight savings time could be at different latitudes. Using computer software like Skycalendar, Excel and Mathematica, latitudes, sunsets and sunrises were recorded for different cities, and averages were obtained of the duration of the daylight per month along a year. With these results the number of daylight hours that overlap with different normal working schedules were calculated under different working-hours assumptions. By comparing results obtained with and without the daylight savings time, the difference in the number of hours with daylight was obtained; that represents the energy savings. Next, the beginning and the ending of the daylight saving time was changed for different dates of the year to obtain those dates that give the greatest savings possible for each latitude. The findings indicate that, in general, from the south of Canada to the north of Mexico, the use of daylight savings time is beneficial.
Special Requirements for Paper:

SPS-13
Name: Kurt William Smith
Affiliation: University of Dallas
Address: 1845 East Northgate Drive, Irving, TX 75062 USA
Phone: 972-579-2986
E-mail: ksmith@udallas.edu
Title: Coulomb Cluster Dynamics: Numerical Simulations
Authors: Kurt W. Smith and Lorin S. Matthews
Description of Paper for Session Arrangement: Coulomb clusters are complex plasma systems in which the maximum number of macro-sized particles is limited $(N \leq 50 )$ and the particles are constrained by an electric potential, forcing the particles to form clusters'' in a two- dimensional plane. The particles in the clusters arrange themselves in concentric rings, orshells,'' at equilibrium. Three aspects of coulomb clusters are studied using a modified box_tree algorithm for particle dynamics: (1) The energy per particle for different sized clusters, (2) cluster rotation via external torque, and (3) single particle injection into an 18 particle cluster. The energy per particle for different particle numbers is demonstrated to be consistent with previous work modeling classically charged particles in parabolic potentials. Cluster rotation is modeled for $2 \leq N \leq 50$, with clusters exhibiting both rigid and differential rotation, depending on the characteristics of the cluster shells. The magic clusters --- those clusters whose shells do not differentially rotate --- are shown to be stable under external torques, reaching an equilibrium between laser torque and gas drag. Differential rotation between cluster shells is also exhibited, and a future model deriving the inter-shell torque transfer under external torques will be developed. Single particle injection into an 18 particle cluster is modeled, with the resulting probabilities of formation for the two most stable states of the 19 particle cluster given as a function of the gas drag. We find a minimum energy for the injected particle which results in second shell penetration, similar to the minimum energy required for a free electron to eject a bound electron from an inner orbital.
Special Requirements for Paper: Require a projector for transparencies.

SPS-14
Name: Daniel Lloyd Mehaffey
Affiliation: University of Dallas
Address: 1845 E. Northgate Dr., Irving , TX 75062 USA
Phone: 972-579-3049
E-mail: dmehaff@udallas.edu
Title: Generation of Blue Laser Radiation at 486nm Using PPLN Waveguide
Authors: Daniel Mehaffey, D. Shiner, A.Khademian
Description of Paper for Session Arrangement: The purpose of this research was developing a convenient and inexpensive laser for atomic spectroscopy. The main approach was to use well developed and commercially available IR semiconductor lasers combined with an efficient frequency doubling stage. In particular a single mode fiber Bragg grating stabilized InGaAs-AlGaAs semiconductor laser at 972nm was used. The efficiency of a newly developed PPLN waveguide commercially available from HC Photoincs Corporation, Taiwan was explored. The current set up and initial tests are discussed.
Special Requirements for Paper: Computer

SPS-15
Name: Karen T Robertson
Affiliation: Angelo State University
Address: ASU Station #10904, San Angelo, TX 76909 USA
Phone: (325)942-2242
E-mail: karen_swimmer@yahoo.com
Title: Deposition of Thin Films for Optoelectronics
Authors: Karen Robertson, Dr. Brian Gorman, Dr. Terry Golding
Description of Paper for Session Arrangement: The goal of this research is to create flat transparent solar cells and blue LED's. Epitaxially grown thin films of Zinc Oxide (ZnO) are known to be blue emitters; unfortunately, this is not cost efficient. Furthermore, the light emitted is not collimated, but can be directed by thin metallic films layers over the ZnO. My work involved producing thin films of ZnO using a spin-coater and a furnace. Further work involved sputter coating gold and silver films onto silicon glass substrates. The Au and Ag films were annealed and observed to become transparent. Funding was provided by NSF through their REU program. My advising professors at the University of North Texas were Dr. Brian Gorman and Dr. Terry Golding.
Special Requirements for Paper: Please provide a projector that is laptop compatible (I will be presenting using Power Point from my laptop).

SPS-16
Name: Evan Bill Stenmark
Affiliation: Tarleton State University
Address: Box T-470, Stephenville, Texas 76402 USA
Phone:254-968-9880
e-mail: st_stenmark@tarleton.edu
Title: Rutherford Backscattering Spectrometry for Materials Analysis
Authors: E. Stenmark, J.R. Gilbert, and D.K. Marble
Description of Paper for Session Arrangement: Rutherford Backscattering Spectromentry (RBS) is an extremely powerful technique for quantitatively analyzing the composition of thin films and profiling heavy elements in light substrates without the need for external standards. Tarleton State University has recently developed a state-of-the-art materials research facility including a new ion accelerator, scanning electron microscope, and x-ray diffractometer. This talk will present both an overview of the new facility and RBS as well as provide examples of our application of RBS to analyze electronic materials in support of externally funded collaborations with other universities, government, and industrial researchers. Work Supported by NSF MRI Grant #DMR-0210162 and Tarleton University Organized Research
Special Requirements for Paper:

SPS-17
Name: Dominic Matthew Seitz
Affiliation: University of Dallas
Phone: (972)721-1947
e-mail: dseitz@udallas.edu
Title: Use of N-V Diamond centers for Quantum Computing Applications
Authors: Dominic Seitz, under supervision of Dr. John Coogan
Description of Paper for Session Arrangement: The purpose of this research was the development of a potential source of qubits to be utilized in the construction of a solid-state type II quantum computer. The goal was to utilize optical Raman interactions to excite spin coherences in solid materials. The Nitrogen-Vacancy (N-V) centers in a treated diamond sample were initially chosen due to previous research demonstrating Raman heterodyne signals, and the possibility of optical resolution of the centers. Its relatively long spin lifetime would allow for a great number of error-free operations to take place. The experimental setup and initial tests will be addressed in this presentation.
Special Requirements for Paper: Undergraduate Competition, computer with projector

SPS-18
Name: Brian McGonagill
Affiliation: Angelo State University
Address: ASU Station #10904, San Angelo, TX 76909 USA
Phone: 325 942 2242
e-mail: sibum@excite.com
Title: Nonlinear Attenuation of Gamma Ray Radiation Due to the Partial Volume Effect
Authors: Brian McGonagill and Charles Allen
Description of Paper for Session Arrangement: When an object only partially occludes a penetrating radiation beam (such as gamma rays), the count rate measured is non-linear in the fractional area of the beam which is occluded. This causes images that rely on this method of data collection (such as computed tomography) to have artifacts. This work shows analytic, simulation, and experimental results for measuring this nonlinearity.
Special Requirements for Paper: transparency projector

SPS-19
Name: Hai Lin
Affiliation: Princeton University
Phone: n/a
E-mail: hailin@princeton.edu
Title: E. coli Random Walks in Geometrically Complex Micron-scale Silicone Structures and its Numerical Simulation by Modified Keller-Segel Theory
Authors: Hai Lin
Description of Paper for Session Arrangement: We study the chemotactic motion of E. coli cells in micron-scale geometrically complex silicone structures to test the ability and efficiency of E. coli to communicate, cooperate with each other for survival and protection reasons. The experiment shows that the initially homogenously distributed E. coli form solitary waves and finally collapse into the most confined regions. These phenomena are due to the inter-cellular communicating ability of E. coli by chemotaxis, which could be described by a set of nonlinear dynamic differential equations, such as in the Keller-Segel theory. We refine the theory of E. coli motion by introducing nutrient fields and other variables coupled to Keller-Segal equations. We achieved the aggregation and wave patterns of E. coli from computer simulation using Matlab, which shows the consistency of the theory and experiment and further indicates a correspondence between E. coli motion and soliton dynamics.
Special Requirements for Paper:

## Poster Session

SPS-20
Name: Geun C Hoang
Affiliation: Division of Physics, Wonkwang Univ.
Address: Jeonbuk 570-749 R. O. K
Phone: 82-63-850-6249
E-mail: gchoang@wonkwang.ac.kr
Title: Analysis of a Ball Movement on Inclined Plane
Authors: Geun C. Hoang
Description of Paper for Session Arrangement: IR photogates were placed on the inclined wooden/ ebonite plane. And metal balls whose diameters of 2.06 cm and 1.91 cm were rolled down freely and passed through the gates. Instantaneous time intervals were measured with respect to inclined angles, and velocities and accelerations were calculated. Through some formula, frictional coefficients were calculated. The state of ball movement was changed from rolling to slipping at the angle of 32±1 degree for wooden board and of 37±1 for ebonite plate, where the coefficient of kinetic friction was 0.178±0.008/ 0.215±0.008 for the wooden/ ebonite plate. The results of this research can be used for Mechanics lab. for physics major students or General physics laboratory.
Special Requirements for Paper: Poster