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Articles 61 - 90 of 368
Full-Text Articles in Physical Sciences and Mathematics
Transiting Exo-Planets Indirect Detection Of Planets Orbiting Other Stars, Brian Shaw, Denise Stephens
Transiting Exo-Planets Indirect Detection Of Planets Orbiting Other Stars, Brian Shaw, Denise Stephens
Journal of Undergraduate Research
Introduction Over the past year I have been looking at pictures filled with dots and running them through computers. On the surface that doesn’t seem quite exciting but once one understands what is happening between the pixels, the humdrum atmosphere disappears. Each of those dots represent an actual star in our galaxy. And by analyzing the pixels, I can determine properties of these stars. The Orson Pratt Observatory atop the Eyring Science Center on BYU campus has been collection data of potential transits provided by the KELT-North Project. I have been taking that data and reducing it to the point …
Magnetic Memory In Exchange Bias Films, Clarke Safsten, Karine Chenel
Magnetic Memory In Exchange Bias Films, Clarke Safsten, Karine Chenel
Journal of Undergraduate Research
My project for which I received an ORCA grant has advanced considerably. I work with Dr. Chesnel studying magnetic thin films. These films consist of layered ferromagnetic and antiferromagnetic materials. In previous experiments, Dr. Chesnel has determined that these types of films exhibit a property called magnetic memory. My project is to determine if the magnetic memory persists, and to what degree, in various circumstances. My project is divided into three primary pieces: experiment, computation, and conclusion.
“Ultra Cold” Room Temperature Plasma, Stephen Rupper, Dr. Scott Bergeson
“Ultra Cold” Room Temperature Plasma, Stephen Rupper, Dr. Scott Bergeson
Journal of Undergraduate Research
Many scientists throughout the world are currently doing research on ultra cold neutral plasmas (UCNP). These plasmas are difficult to make and require quite a sophisticated setup. A method that we employ in our lab requires multiple laser pulses to be timed perfectly and aligned precisely in order to ionize the atoms. It also requires the use of a magneto optical trap, which traps the atoms before they are ionized. This setup is very time consuming to build and maintain but we have a mathematical model for it. Since the current methods of creating ultra cold plasmas are hard to …
Determining Thin Film Roughness With Euv Reflection, Cody Petrie, Steven Turley
Determining Thin Film Roughness With Euv Reflection, Cody Petrie, Steven Turley
Journal of Undergraduate Research
Introduction: Reflection of extreme ultraviolet (EUV) light is made difficult by a number of factors. First, most materials have a large, imaginary part of the index of refraction for EUV light, causing absorption. As a result, our experiment is done under vacuum. Second, since the wavelength of EUV light (1-100 nm) is smaller than visible light, it is scattered more strongly than visible light. To overcome this obstacle we need to make our reflecting surfaces smoother. To be able to do this we need a good probe for surface roughness on the scale of EUV wavelengths. Currently the best method …
Wavelength Detection From Filtered Photodiodes, Nils Otterstrom, Dallin Durfee
Wavelength Detection From Filtered Photodiodes, Nils Otterstrom, Dallin Durfee
Journal of Undergraduate Research
Introduction Physics laboratories all over the world depend on accurate wavelength meters to tune their lasers to desired optical frequencies. Our ion interferometry lab, for example, relies heavily on the precision of these instruments to laser cool beams of strontium ions and then split and recombine their wave functions. Unfortunately, some these devices can be extremely expensive and very cumbersome to use. A frequency comb wavelength detector, although remarkably accurate, can cost around $100,000 dollars. In our lab we employ a Michelson-Morley interferometer based wavelength meter, which costs around $8,000 dollars. Despite its relatively high accuracy, the device is extremely …
Porous Cantilevers As Chemical Sensors, Steven Noyce, Robert Davis
Porous Cantilevers As Chemical Sensors, Steven Noyce, Robert Davis
Journal of Undergraduate Research
Resonant cantilevers, or small vibrating beams, are used to detect small concentrations of chemicals. As molecules or atoms of the substance to be sensed adhere to the vibrating beam, the resonant frequency changes as a result of the change in mass. These sensors are built on the microscale to allow for mass parallelization. An array of cantilevers could each be coated with a different adhesion layer, making each beam sensitive to a unique substance. These sensors have previously been made of solid materials, but because the sensitivity is proportional to the surface area of the resonator, a porous cantilever could …
Chaotic Scattering In General Relativity, Taylor Hugh Morgan, David Neilsen
Chaotic Scattering In General Relativity, Taylor Hugh Morgan, David Neilsen
Journal of Undergraduate Research
I. Introduction Our research is on the gravitational three-body problem where there are three star-like objects with the only acting force on the objects being gravity. Since the discovery of gravity, many physicists and mathematicians have looked for an analytic solution to the three-body problem including Poincare, Euler, Lagrange, and Jacobi. We now know that there is in fact no analytic solution to this problem. Due to the advent of high performance computing we have discovered much about the chaotic nature1 of this problem and its sensitivity to initial perturbations. For our research we have extended the scope of the …
Determining Surface Roughness Using Extreme Ultraviolet Light, Joshua Marx, Steve Turley
Determining Surface Roughness Using Extreme Ultraviolet Light, Joshua Marx, Steve Turley
Journal of Undergraduate Research
Extreme ultraviolet (XUV) light is light with wavelengths between one and 60 nanometers. The shorter wavelengths of light in this range are on the same order of magnitude as atomic dimensions. Currently, XUV optics have many uses and even more potential applications in a variety of fields, such as photolithography, plasma diagnostics, and astrophysics.
Science In A Nutshell: Studying The Use Of Humor In Science Writing, Meredith Gold, Gus Hart
Science In A Nutshell: Studying The Use Of Humor In Science Writing, Meredith Gold, Gus Hart
Journal of Undergraduate Research
Introduction The purpose of this study was to expand upon a previous and successful unofficial study that I did in high school, testing the effectiveness of humor in instructional science writing. Despite the fact that various extenuating circumstances (including multiple cases of prolonged illness) hindered measurable data collection, the first main question asked by the study was answered: It is even possible to write a physics textbook in the style of humor essays? To this, my project responds with a resounding yes. I wrote and began editing the full first draft of my first humorous physics textbook, coming in at …
Relating Quantum Dynamics And Entanglement, John Gardiner, Jean-Francois Van Huele
Relating Quantum Dynamics And Entanglement, John Gardiner, Jean-Francois Van Huele
Journal of Undergraduate Research
Introduction Entanglement is a quantum phenomenon that is important to many applications including quantum computing and cryptography. The way that a quantum system changes in time is encoded in a mathematical object called the Hamiltonian of the system. The goal of this project was to better understand the relation between the quantum dynamics of a system, as described by the Hamiltonian, and the entanglements that arise in the system, with the bigger goal of better understanding how entanglement changes in time. To this end I studied computer simulations of simple quantum systems to observe how certain features of the Hamiltonian …
Pharm: An Environment For Physical Acoustics Research And Mentoring, Kent L. Gee, Tracianne B. Neilsen
Pharm: An Environment For Physical Acoustics Research And Mentoring, Kent L. Gee, Tracianne B. Neilsen
Journal of Undergraduate Research
PHARM (PHysical Acoustics Research and Mentoring) has been operating partially with support from a MEG grant. The primary purpose of this mentoring environment is to provide undergraduates in Physics and Applied Physics opportunities to gain experience in fundamental areas of physical acoustics. It has also included students in Mechanical and Electrical Engineering and Mathematics. Within the acoustics community, “physical acoustics” refers to a number of subfields (e.g., outdoor sound propagation, aeroacoustics, and nonlinear acoustics). A large number of students have been able to participate in projects related to these areas. Many of these projects have been and are being documented …
Magnetic Order And Fluctuation Dynamics Of Self-Assembled Magnetite Fe3o4 Nanoparticles, Karine Chesnel
Magnetic Order And Fluctuation Dynamics Of Self-Assembled Magnetite Fe3o4 Nanoparticles, Karine Chesnel
Journal of Undergraduate Research
The research plan described in the proposal (section 2.1) was well implemented during the period 2013-2014. Most of the steps listed in the plan were completed thanks to the fund: (1) nanoparticle preparation (2) structural characterization (3) magnetic characterization (4) particle deposition and self-assembling (5) net magnetization of the film measured via XMCD; we are still working on the last steps (6) magnetic order between particles measured via XRMS and (7) dynamical measurements, measured via CXRMS. The fund was especially useful to go and carry out a couple of synchrotron experiments at SSRL, SLAC at Stanford, to complete steps (5-7). …
Improvement Of Atomic Layer Deposition Techniques Of Tungsten Using Hydrogen As A Reducing Agent, Jason Kyle Anderson, Dr. David Allred
Improvement Of Atomic Layer Deposition Techniques Of Tungsten Using Hydrogen As A Reducing Agent, Jason Kyle Anderson, Dr. David Allred
Journal of Undergraduate Research
Introduction: Traditional micro fabrication processes are confined to a small subset of possible materials due to limitations on etching. They are also confined to low aspect ratio fabrication due to limits in both etching process and stability of thicker film deposition processes. Carbon Nanotube Templated Microfabrication (CNT-M) technology has introduced a dramatically different approach to micro fabrication that fabricates without significant etching processes and achieves thick features with the equivalent of thin depositions. This is achieved by forming the desired structure in carbon nanotubes and then filling, or infiltrating, that structure with the material of choice. Optimal materials infiltration for …
Sound Reduction In Protheses For Developing Countries, Ashlie Burton, Lawrence Rees
Sound Reduction In Protheses For Developing Countries, Ashlie Burton, Lawrence Rees
Journal of Undergraduate Research
Introduction 2ft Prosthetics has been making below-the-knee prostheses for developing countries since 2010. While these feet have been helpful, improvements should be made to the design. One of the common complaints about the PVC foot was the amount of noise created during gait. The purpose of this project was to research different sound reduction designs for the PVC prosthesis. Initially two designs were drafted, out of the two, one was built and tested.
Radio Emission Toward Regions Of Massive Star Formation In The Large Magellanic Cloud, Adam Johanson
Radio Emission Toward Regions Of Massive Star Formation In The Large Magellanic Cloud, Adam Johanson
Theses and Dissertations
Four regions of massive star formation in the Large Magellanic Cloud (LMC) were observed for water and methanol maser emission and radio continuum emission. A total of 42 radio detections were made including 27 new radio sources, four water masers, and eight compact HII regions. The lobes of a radio galaxy were resolved for the first time, and the host galaxy identified. Seven sources were associated with known massive young stellar objects (YSOs). A multi-wavelength analysis using both the infrared and radio spectrum was used to characterize the sources. Mid-infrared color-magnitude selection criteria for ultracompact HII (UCHII) regions in the …
Simulations Of Electron Trajectories In An Intense Laser Focus For Photon Scattering Experiments, Grayson J. Tarbox
Simulations Of Electron Trajectories In An Intense Laser Focus For Photon Scattering Experiments, Grayson J. Tarbox
Theses and Dissertations
An experiment currently underway at BYU is designed to test whether the size of a free electron wave packet affects the character of scattered radiation. Using a semi-classical argument wherein the wave packet is treated as a diffuse charge distribution, one would expect strong suppression of radiation in the direction perpendicular to the propagating field as the wave packet grows in size to be comparable to the wavelength of the driving field. If one disallows the interaction of the wave packet with itself, as is the case when calculating the rate of emission using QED, then regardless of size, the …
Instrument For Precision Long-Term Ss-Decay Rate Measurements, M. J. Ware, Scott D. Bergeson, J. E. Ellsworth, M. Groesbeck, J. E. Hansen, D. Pace, J. Peatross
Instrument For Precision Long-Term Ss-Decay Rate Measurements, M. J. Ware, Scott D. Bergeson, J. E. Ellsworth, M. Groesbeck, J. E. Hansen, D. Pace, J. Peatross
Faculty Publications
We describe an experimental setup for making precision measurements of relative ß-decay rates of 22Na, 36Cl, 54Mn, 60Co, 90Sr, 133Ba, 137Cs, 152Eu, and 154Eu. The radioactive samples are mounted in two automated sample changers that sequentially position the samples with high spatial precision in front of sets of detectors. The set of detectors for one sample changer consists of four Geiger-Müller (GM) tubes and the other set of detectors consists of two NaI scintillators. The statistical uncertainty in the count rate is few times 0.01% per day for the GM …
Strongly-Coupled Plasmas Formed From Laser-Heated Solids, M. Lyon, Scott D. Bergeson, G. Hart, M. S. Murillo
Strongly-Coupled Plasmas Formed From Laser-Heated Solids, M. Lyon, Scott D. Bergeson, G. Hart, M. S. Murillo
Faculty Publications
We present an analysis of ion temperatures in laser-produced plasmas formed from solids with different initial lattice structures. We show that the equilibrium ion temperature is limited by a mismatch between the initial crystallographic configuration and the close-packed configuration of a strongly-coupled plasma, similar to experiments in ultracold neutral plasmas. We propose experiments to demonstrate and exploit this crystallographic heating in order to produce a strongly coupled plasma with a coupling parameter of several hundred.
Using Higher Ionization States To Increase Coulomb Coupling In An Ultracold Neutral Plasma, M. Lyon, Scott D. Bergeson, A. Diaw, M. S. Murillo
Using Higher Ionization States To Increase Coulomb Coupling In An Ultracold Neutral Plasma, M. Lyon, Scott D. Bergeson, A. Diaw, M. S. Murillo
Faculty Publications
We report measurements and simulations of the time-evolving rms velocity distribution in an ultracold neutral plasma. A strongly coupled ultracold neutral Ca+ plasma is generated by photoionizing laser-cooled atoms close to threshold. A fraction of these ions is then promoted to the second ionization state to form a mixed Ca+-Ca2+ plasma. By varying the time delay between the first and the second ionization events, a minimum in ion heating is achieved. We show that the Coulomb strong-coupling parameter Γ increases by a factor of 1.4 to a maximum value of 3.6. A pure Ca2+ plasma …
Algebraic Semi-Classical Model For Reaction Dynamics, Tim Glenn Wendler
Algebraic Semi-Classical Model For Reaction Dynamics, Tim Glenn Wendler
Theses and Dissertations
We use an algebraic method to model the molecular collision dynamics of a collinear triatomic system. Beginning with a forced oscillator, we develop a mathematical framework upon which inelastic and reactive collisions are modeled. The model is considered algebraic because it takes advantage of the properties of a Lie algebra in the derivation of a time-evolution operator. The time-evolution operator is shown to generate both phase-space and quantum dynamics of a forced oscillator simultaneously. The model is considered semi-classical because only the molecule's internal degrees-of-freedom are quantized. The relative translation between the colliding atom and molecule in an exchange reaction …
Towards Stronger Coulomb Coupling In An Ultracold Neutral Plasma, Mary Elizabeth Lyon
Towards Stronger Coulomb Coupling In An Ultracold Neutral Plasma, Mary Elizabeth Lyon
Theses and Dissertations
Ultracold neutral plasmas are created by photoionizing laser-cooled atoms in a magneto-optical trap (MOT). Due to their large electrical potential energies and comparatively small kinetic energies, ultracold plasmas fall into a regime of plasma systems which are called “strongly coupled.” A priority in the field of ultracold plasmas is to generate plasmas with higher values of the strong coupling parameter Γ, which is given as the ratio of the nearest-neighbor Coulomb potential energy to the average kinetic energy. The equilibrium strong coupling in ultracold plasmas is limited by the ultrafast relaxation of the ions due to spatial disorder in the …
Investigation Of A New Method Of Estimating Acoustic Intensity And Its Application To Rocket Noise, Benjamin Young Christensen
Investigation Of A New Method Of Estimating Acoustic Intensity And Its Application To Rocket Noise, Benjamin Young Christensen
Theses and Dissertations
An alternative pressure-sensor based method for estimating the acoustic intensity, the phase and amplitude gradient estimation (PAGE) method, is presented. This method is similar to the finite-difference p-p (FD) method, in which the intensity is estimated from pressure measurements made using an array of closely spaced microphones. The PAGE method uses the same hardware as the FD method, but does not suffer from the frequency-dependent bias inherent to the FD method. Detailed derivations of the new method and the traditional FD method are presented. Both methods are then compared using two acoustic fields: a plane wave and a three monopole …
The Use Of Object-Oriented Programming Concepts For Documenting A Model Ensemble, Georgii A. Alexandrov
The Use Of Object-Oriented Programming Concepts For Documenting A Model Ensemble, Georgii A. Alexandrov
International Congress on Environmental Modelling and Software
The spread of cloud computing services gives community modelling a reasonable opportunity to become a reality in scientific research. However, even if models will be deployed in clouds, and model codes will be open for re-use, there will be little progress in community modelling in the lack of consensus standards for model documentation. This paper is to discuss a conceptual framework for developing such standards. The proposed conceptual framework is based on the idea that a new model is often a modification of an old one, and hence, the similarities between the models of the same environmental process could be …
Application Of An Isogeometric Boundary Element Method To The Calculation Of Acoustic Radiation Modes And Their Efficiencies, Candice Marie Humpherys
Application Of An Isogeometric Boundary Element Method To The Calculation Of Acoustic Radiation Modes And Their Efficiencies, Candice Marie Humpherys
Theses and Dissertations
In contrast to the structural modes, which describe the physical motion of vibrating structures, acoustic radiation modes describe the radiated sound power. Radiation modes are beneficial in active noise control because reducing an efficiently radiating radiation mode guarantees the reduction of radiated sound power. Much work has been done to calculate the radiation modes for simple geometries, where analytic solutions are available. In this work, isogeometric analysis (IGA) is used to provide a tool capable of analyzing the radiation modes of arbitrarily complex geometries. IGA offers increased accuracy and efficiency by using basis functions generated from Non-Uniform Rational B-Splines (NURBS) …
Spin And Orbital Moments And Magnetic Order In Fe3o4 Nanoparticle Assemblies, Yanping Cai
Spin And Orbital Moments And Magnetic Order In Fe3o4 Nanoparticle Assemblies, Yanping Cai
Theses and Dissertations
Fe3O4 magnetic nanoparticles of 5 to 11 nm in size were prepared by organic methods. Particle size was analyzed by both X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM) techniques. Zero Field Cooling (ZFC) / Field Cooling (FC) and magnetization loop measurements were recorded by VSM, and they confirmed superparamagnetic behavior in the sample. The blocking temperature is found to be in the range of 30 K ~ 170 K. It has a dependence on the particle size. ZFC / FC curves also indicate the presence of magnetic coupling between particles. X-ray Magnetic Circular Dichroism (XMCD) measurements of these nanoparticles …
Estimating The Acoustic Power Of Sources In Nonideal Enclosures Using Generalized Acoustic Energy Density, Daniel Ryan Marquez
Estimating The Acoustic Power Of Sources In Nonideal Enclosures Using Generalized Acoustic Energy Density, Daniel Ryan Marquez
Theses and Dissertations
Sound power measurements of acoustic sources are generally made in reverberation or anechoic chambers using acoustic pressure measurements as outlined in specific ISO or other standards. A reverberation chamber produces an approximate diffuse-field condition, wherein the sound power is determined from the spatially averaged squared pressure. An anechoic chamber produces an approximate free-field condition, wherein the sound power is estimated from squared pressure over an enveloping measurement surface. However, in many cases it is desirable to estimate sound power within nonideal semi-reverberant spaces. In these environments, both direct and reverberant energies may contribute significantly to the total acoustic field. This …
Development And Validation Of An Automated Directivity Acquisition System Used In The Acquisition, Processing, And Presentation Of The Acoustic Far-Field Directivity Of Musical Instruments In An Anechoic Space, Nicholas J. Eyring
Theses and Dissertations
A high spatial resolution acoustic directivity acquisition system (ADAS) has been developed to acquire anechoic measurements of the far field radiation of musical instruments that are either remote controlled or played by musicians. Building upon work performed by the BYU Acoustic Research Group in the characterization of loudspeaker directivity, one can rotate a musical instrument with sequential azimuthal angle increments under a fixed semicircular array of microphones while recording repeated notes or sequences of notes. This results in highly detailed and instructive directivity data presented in the form of high-resolution balloon plots. The directivity data and corresponding balloon plots may …
Analyses Of Nonlinearity Measures In High-Amplitude Sound Propagation, Michael B. Muhlestein
Analyses Of Nonlinearity Measures In High-Amplitude Sound Propagation, Michael B. Muhlestein
Theses and Dissertations
Military aircraft generate high-amplitude noise which can cause injury to attending personnel. Efforts to mitigate the effects of this noise require a detailed understanding of the propagation of the noise, which was shown previously to be nonlinear. This thesis presents an analysis of high-amplitude noise propagation, emphasizing measures used to quantify the importance of considering nonlinearity. Two measures of the importance of nonlinearity are compared. These measures are the wave steepening factor and a skewness estimate. The wave steepening factor is a measure of how much nonlinear waveform steepening has occurred in a waveform. The skewness estimate is the skewness …
Characterization Of Ingaas Quantum Dot Chains, Tyler Drue Park
Characterization Of Ingaas Quantum Dot Chains, Tyler Drue Park
Theses and Dissertations
InGaAs quantum dot chains were grown with a low-temperature variation of the Stranski-Krastanov method, the conventional epitaxial method. This new method seeks to reduce indium segregation and intermixing in addition to giving greater control in the growth process. We used photoluminescence spectroscopy techniques to characterize the quality and electronic structure of these samples. We have recently used a transmission electron microscope to show how the quantum dots vary with annealing temperature. Some questions relating to the morphology of the samples cannot be answered by photoluminescence spectroscopy alone. Using transmission electron microscopy, we verified flattening of the quantum dots with annealing …
Simulation Of 810 Nm Light Propagation Through The Human Finger For Non-Invasive Blood Analysis, Nichole Millward Maughan
Simulation Of 810 Nm Light Propagation Through The Human Finger For Non-Invasive Blood Analysis, Nichole Millward Maughan
Theses and Dissertations
Non-invasive blood analysis devices that can measure characteristics less prominent than the oxygenation of hemoglobin are of interest in the medical community. An important step in creating these devices is to model the interaction of photons with human tissue in increasingly greater physiological detail. We have modeled, using a Monte Carlo technique, the interaction of photons through epidermis, blood and water arranged both in layers and in a homogeneous mixture. We confirm the expected linear relation between photon attenuation and material volumetric percentage in our two-layer models. We discovered that this relationship becomes non-linear in the homogeneously mixed models where …