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2013

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Articles 241 - 270 of 1248

Full-Text Articles in Physics

Pulsed Electro-Acoustic (Pea) Measurements Of Embedded Charge Distributions, Jr Dennison, Lee H. Pearson Sep 2013

Pulsed Electro-Acoustic (Pea) Measurements Of Embedded Charge Distributions, Jr Dennison, Lee H. Pearson

Conference Proceedings

Knowledge of the spatial distribution and evolution of embedded charge in thin dielectric materials has important applications in semiconductor, high-power electronic device, high-voltage DC power cable insulation, high-energy and plasma physics apparatus, and spacecraft industries. Knowing how, where, and how much charge accumulates and how it redistributes and dissipates can predict destructive charging effects. Pulsed Electro-acoustic (PEA) measurements— and two closely related methods, Pressure Wave Propagation (PWP) and Laser Intensity Modulation (LIMM)— nondestructively probe such internal charge distributions. We review the instrumentation, methods, theory and signal processing of simple PEA experiments, as well as the related PPW and LIMM methods. …

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Comment On "Unified Formalism Of Adreev Reflection At A Ferromagnet/Superconductor Interface", M. Eschrig, A. A. Golubov, I. I. Mazin, B. Nadgorny, Y. Tanaka, O. T. Valls, Igor Žutić Sep 2013

Comment On "Unified Formalism Of Adreev Reflection At A Ferromagnet/Superconductor Interface", M. Eschrig, A. A. Golubov, I. I. Mazin, B. Nadgorny, Y. Tanaka, O. T. Valls, Igor Žutić

Physics and Astronomy Faculty Research Publications

A Comment on the Letter by T. Y. Chen et al., Phys. Rev. Lett. 109 146602 (2012) The authors of the Letter offer a Reply.

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Image Deblurring And Near-Real-Time Atmospheric Seeing Estimation Through The Employment Of Convergence Of Variance, Brian J. Neff, Quentin D. Macmanus, Stephen C. Cain, Richard K. Martin Sep 2013

Image Deblurring And Near-Real-Time Atmospheric Seeing Estimation Through The Employment Of Convergence Of Variance, Brian J. Neff, Quentin D. Macmanus, Stephen C. Cain, Richard K. Martin

Faculty Publications

A new image reconstruction algorithm is presented that will remove the effect of atmospheric turbulence on motion compensated frame average images. The primary focus of this research was to develop a blind deconvolution technique that could be employed in a tactical military environment where both time and computational power are limited. Additionally, this technique can be employed to measure atmospheric seeing conditions. In a blind deconvolution fashion, the algorithm simultaneously computes a high resolution image and an average model for the atmospheric blur parameterized by Fried’s seeing parameter. The difference in this approach is that it does not assume a …

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Freeze-Out Dynamics Via Charged Kaon Femtoscopy In √ Snn = 200 Gev Central Au + Au Collisions, L. Adamczyk, E. Elnimr, S. Lapointe, C. Pruneau, J. Putschke, M. Sharma, L. H. Tarini, S. A. Voloshin, Star Collaboration Sep 2013

Freeze-Out Dynamics Via Charged Kaon Femtoscopy In √ Snn = 200 Gev Central Au + Au Collisions, L. Adamczyk, E. Elnimr, S. Lapointe, C. Pruneau, J. Putschke, M. Sharma, L. H. Tarini, S. A. Voloshin, Star Collaboration

Physics and Astronomy Faculty Research Publications

We present measurements of three-dimensional correlation functions of like-sign, low-transverse-momentum kaon pairs from √sNN=200 GeV Au+Au collisions. A Cartesian surface-spherical harmonic decomposition technique was used to extract the kaon source function. The latter was found to have a three-dimensional Gaussian shape and can be adequately reproduced by Therminator event-generator simulations with resonance contributions taken into account. Compared to the pion one, the kaon source function is generally narrower and does not have the long tail along the pair transverse momentum direction. The kaon Gaussian radii display a monotonic decrease with increasing transverse mass mT over …

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Technical Advantages For Weak-Value Amplification: When Less Is More, Andrew N. Jordan, Julián Martínez-Rincón, John C. Howell Sep 2013

Technical Advantages For Weak-Value Amplification: When Less Is More, Andrew N. Jordan, Julián Martínez-Rincón, John C. Howell

Mathematics, Physics, and Computer Science Faculty Articles and Research

The technical merits of weak-value-amplification techniques are analyzed. We consider models of several different types of technical noise in an optical context and show that weak-value-amplification techniques (which only use a small fraction of the photons) compare favorably with standard techniques (which use all of them). Using the Fisher-information metric, we demonstrate that weak-value techniques can put all of the Fisher information about the detected parameter into a small portion of the events and show how this fact alone gives technical advantages. We go on to consider a time-correlated noise model and find that a Fisher-information analysis indicates that the …

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Finite-Temperature Properties Of Strongly Correlated Fermions In The Honeycomb Lattice, Baoming Tang, Thereza Paiva, Ehsan Khatami, Marchos Rigol Sep 2013

Finite-Temperature Properties Of Strongly Correlated Fermions In The Honeycomb Lattice, Baoming Tang, Thereza Paiva, Ehsan Khatami, Marchos Rigol

Faculty Publications

We study finite-temperature properties of strongly interacting fermions in the honeycomb lattice using numerical linked-cluster expansions and determinantal quantum Monte Carlo simulations. We analyze a number of thermodynamic quantities, including the entropy, the specific heat, uniform and staggered spin susceptibilities, short-range spin correlations, and the double occupancy at and away from half filling. We examine the viability of adiabatic cooling by increasing the interaction strength for homogeneous as well as for trapped systems. For the homogeneous case, this process is found to be more efficient at finite doping than at half filling. That, in turn, leads to an efficient adiabatic …

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Ultra-Stable Laser For Use In A Next Generation Atom Interferometer, Brian Neyenhuis, Dr. Dallin Durfee Sep 2013

Ultra-Stable Laser For Use In A Next Generation Atom Interferometer, Brian Neyenhuis, Dr. Dallin Durfee

Journal of Undergraduate Research

Laser diodes are an attractive option for atomic physics research. They are small, available in a wide variety of wavelengths, inexpensive, and require little power. Because diode lasers are typically made in bulk for the computing or telecom industries where linewidth and mode structure are not generally important, a solitary diode usually has a linewidth on the order of GHz and often runs multi-mode. By placing the diode in an extended cavity the finesse of the laser cavity can be increased, narrowing the linewidth of the laser to a few hundred kHz. For even narrower linewidths a diode laser is …

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Snyder Space And Non-Commutative Quantum Mechanics, Mark Transtrum, Dr. Jean-Francois Van Huele Sep 2013

Snyder Space And Non-Commutative Quantum Mechanics, Mark Transtrum, Dr. Jean-Francois Van Huele

Journal of Undergraduate Research

Non-commutative quantum mechanics is an active field of research in which the operators corresponding to different spatial dimensions are assumed to not commute, as a consequence of quantization of spacetime. This field is important because it investigates the relationships between fundamental physical ideas such as space, time, momentum, and position on very small scales and will provide the basis for experiments probing these small scales in the future.

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An Ultra-Stable Laser Current Controller, Marshall Van Zijll, Dr. Dallin Durfee Sep 2013

An Ultra-Stable Laser Current Controller, Marshall Van Zijll, Dr. Dallin Durfee

Journal of Undergraduate Research

Our research group has spent lots of effort and time building an ultra-stable laser current controller. This stability is essential for our application of atom interferometry so that our measurements could be very precise. The overall development of our controller has taken almost a year longer than expected, but regarding the results we have obtained it was time well spent. The specific part of the controller I focused on was the microprocessor and it’s relation to the DAC (digital to analog converter), so I will explain the processes I went through.

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Vanadium Dioxide Deposited Substrates For Thermochromic Applications, S. Andrew Ning, Dr. David Allred Sep 2013

Vanadium Dioxide Deposited Substrates For Thermochromic Applications, S. Andrew Ning, Dr. David Allred

Journal of Undergraduate Research

As the technology was readily available here at BYU, we decided to make our own electrochromic material to meet our specifications. After a literature review we found a study done by Wang et al. [1] which suggests a preparation method using a thin film of vanadium dioxide to coat glass. Vanadium dioxide is a fascinating material for its property of undergoing a phase transition from a semiconductor to a metal at a temperature of around 68°C [2]. This change in state is accompanied with a change in its optical properties. It can reversibly change from a state of reflectance to …

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2-Dimensional Magnetic Transducers For Stringed Instruments, Brandon Skinner, Dr. Tim Leishman Sep 2013

2-Dimensional Magnetic Transducers For Stringed Instruments, Brandon Skinner, Dr. Tim Leishman

Journal of Undergraduate Research

The idea for this project came at a time when I was learning many new things about sound, electronics, and electromagnetic theory. In fact, it was the combination of these ideas that lead me to question the functioning of magnetic guitar pickups and to wonder if there was a more complete way to represent the sound of a vibrating string. Actually, sound is a bit of a misnomer here because with a magnetic transducer, we are measuring the physical motion of the string and not the acoustic waves it also happens to cause. With guitar pickups and other magnetic transducers, …

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Dna As A Potential Molecular Nanowire, Richard Marsh, Dr. James P. Lewis Sep 2013

Dna As A Potential Molecular Nanowire, Richard Marsh, Dr. James P. Lewis

Journal of Undergraduate Research

In the world today there is an immense interest in the field of nanotechnology. One particularly unique aspect is that of molecular electronics. The ability to take one molecule and use it as a transistor has many applications. While the transistors on our current computers are in the order of micrometer, a molecular wire has the capability of taking transistors into the nanoscale region. Such a development would drastically increase computer speed, and make the next generation of computers more compact and more manageable. One possibility for this nano-wire is DNA. DNA has several electronic properties that could possibly render …

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X-Ray Photoelectron Spectroscopy To Examine Molecular Composition, Amy Grigg, Dr. Steve Turley Sep 2013

X-Ray Photoelectron Spectroscopy To Examine Molecular Composition, Amy Grigg, Dr. Steve Turley

Journal of Undergraduate Research

The extreme ultraviolet (EUV) spectrum is becoming increasingly important. Its most promising applications include lithography for integrated circuits, space-based astronomy, and medical microscopes. Unfortunately, the optical constants of materials, particularly heavy metals, in this range are not well known. This work examines the molecular composition and oxidation rate and depth of thorium. Most of our data is collected through the use of X-ray Photoelectron Spectroscopy (XPS). XPS utilizes the photoelectric effect to obtain data about the exact composition of our material. X-rays are directed at the surface in question, colliding with and dispelling electrons from different energy levels of atoms. …

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Use Of 2 Mev Proton-Based Pixe In Compositional Analysis Of Paint Pigments, Benjamin Hall, Dr. Lawrence Rees Sep 2013

Use Of 2 Mev Proton-Based Pixe In Compositional Analysis Of Paint Pigments, Benjamin Hall, Dr. Lawrence Rees

Journal of Undergraduate Research

Using the resources provided by this grant, Dr. Rees and I set out to classify the pigments used in artistic oil painting according to their elemental composition. This we did using proton-based Particle-Induced X-ray Emission (PIXE) spectroscopy. Our goal in this portion of the research was to test the feasibility of creating a baseline set of known compositions against which to compare unknown and or mixed pigments.

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X-Ray Powder-Diffraction Simulations Of Large-Scale Defect-Structure Models, Jared Dickson, Dr. Branton Campbell Sep 2013

X-Ray Powder-Diffraction Simulations Of Large-Scale Defect-Structure Models, Jared Dickson, Dr. Branton Campbell

Journal of Undergraduate Research

Open-framework compounds, most notably the aluminosilicate zeolites, play a critical role in modern technology. Their robust crystalline structures contain large cavities and channels of molecular dimensions which make them useful as molecular sieves (desiccants, membrane filters, gas-separators), ion-exchangers (soaps, detergents, water softeners, radioactive waste sequestering agents), chemical catalysts (e.g. petroleum refinement), and nanomaterial growth templates. The many uses of open-framework materials arise from having size and shape-selective pore systems that determine which molecules can enter and what happens to them while inside. Once their structure-property relationships are well characterized, researchers commonly tune the useful properties of open-framework materials by modifying …

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Wave Function For Time-Dependent Harmonically Confined Electrons In A Time-Dependent Electric Field, Yu-Qi Li, Xiao-Yin Pan, Viraht Sahni Sep 2013

Wave Function For Time-Dependent Harmonically Confined Electrons In A Time-Dependent Electric Field, Yu-Qi Li, Xiao-Yin Pan, Viraht Sahni

Publications and Research

The many-body wave function of a system of interacting particles confined by a time-dependent harmonic potential and perturbed by a time-dependent spatially homogeneous electric field is derived via the Feynman path-integral method. The wave function is comprised of a phase factor times the solution to the unperturbed time-dependent Schrödinger equation with the latter being translated by a time-dependent value that satisfies the classical driven equation of motion. The wave function reduces to that of the Harmonic Potential Theorem wave function for the case of the time-independent harmonic confining potential.

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Analysis Of The Variable Star V402 Cephei, Summer Dale Beckstrand, Michael D. Joner Sep 2013

Analysis Of The Variable Star V402 Cephei, Summer Dale Beckstrand, Michael D. Joner

Journal of Undergraduate Research

The evolution of stars is critical to understanding the universe. Many stars go through a stage of instability in their lifetimes. When they are in this stage they are referred to as “intrinsic variable stars,” or pulsators. These stars pulsate, that is they expand and contract periodically, which causes luminosity variations. The study of intrinsic variable stars helps us to better understand the evolution of these stars.

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Additional Elements For Improving The Accuracy Of The Compositional Analysis Of Bullet Lead, Will Ashby, Dr. Lawrence B. Rees Sep 2013

Additional Elements For Improving The Accuracy Of The Compositional Analysis Of Bullet Lead, Will Ashby, Dr. Lawrence B. Rees

Journal of Undergraduate Research

Bullets often mutate or fragment upon impact. This can erase physical markings such as rifling. Until the development in the mid 1900s of techniques for precisely analyzing elemental compositions of materials such as lead, forensics scientists could do nothing to compare bullets obtained from a suspect to mutated or fragmented bullets from a crime scene. Around 1960 forensic scientists began performing the compositional analysis of bullet lead (CABL). The compositions of the bullets from a suspect were compared to the composition of the mutated bullet or fragment from a crime scene in an attempt to identify the guilty suspect [1]. …

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Rayleigh Lidar Observations Of The Mid-Latitude Mesosphere During Stratospheric Warming Events And A New Rayleigh-Mie-Raman Lidar At Usu, Leda Sox, Vincent B. Wickwar, Chad Fish, Joshua P. Herron, Matthew T. Emerick Sep 2013

Rayleigh Lidar Observations Of The Mid-Latitude Mesosphere During Stratospheric Warming Events And A New Rayleigh-Mie-Raman Lidar At Usu, Leda Sox, Vincent B. Wickwar, Chad Fish, Joshua P. Herron, Matthew T. Emerick

Presentations

No abstract provided.

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Computation Of Radial Density Profiles Of A Warm, Nonneutral Plasma Pancake, Deborah L. Paulson, Dr. Ross L. Spencer Sep 2013

Computation Of Radial Density Profiles Of A Warm, Nonneutral Plasma Pancake, Deborah L. Paulson, Dr. Ross L. Spencer

Journal of Undergraduate Research

When a cloud of charged particles is contained in a Penning Trap, it can be observed to flatten into a disc. The measurement of physical properties of these pancake-like plasmas, such as density and temperature, is difficult or impossible without destroying the plasma in the process. In order to determine such physical properties, it is necessary to find a relation between an observable quantity and the other physical properties of the plasma. The observable quantity is the frequency of a normal mode of oscillation.

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Reactive Gas Sputtering Of Lithium Compound Thin Films, Gregory B. Thompson, Dr. David D. Allred Sep 2013

Reactive Gas Sputtering Of Lithium Compound Thin Films, Gregory B. Thompson, Dr. David D. Allred

Journal of Undergraduate Research

This research project reports the reactive gas sputtering deposition and structural characterization of lithium compound thin films (LiH and LiF). These materials, due to their low absorption, may have a role as spacer layers in soft x-ray multilayer reflectors. A multilayer is a periodic, alternating structure of a high density and low density (spacer layer) material stacked one on top of another. These materials reflect x-rays by the superposition of the multiple reflections that occur within the multilayer stack. These reflections can be modeled by Bragg’s condition, given as, n=2dsin, where n is an integer, is the wavelength, d is …

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Detecting The Rapidly Expanding Outer Shell Of The Crab Nebula: Where To Look, Xiang Wang, Gary J. Ferland, J. A. Baldwin, E. D. Loh, C. T. Richardson Sep 2013

Detecting The Rapidly Expanding Outer Shell Of The Crab Nebula: Where To Look, Xiang Wang, Gary J. Ferland, J. A. Baldwin, E. D. Loh, C. T. Richardson

Physics and Astronomy Faculty Publications

We present a range of steady-state photoionization simulations, corresponding to different assumed shell geometries and compositions, of the unseen postulated rapidly expanding outer shell to the Crab Nebula. The properties of the shell are constrained by the mass that must lie within it, and by limits to the intensities of hydrogen recombination lines. In all cases the photoionization models predict very strong emissions from high ionization lines that will not be emitted by the Crab's filaments, alleviating problems with detecting these lines in the presence of light scattered from brighter parts of the Crab. The near-NIR [Ne VI] λ7.652 μ …

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Examining Photocatalysis In Tio2, Daniel Jensen, Dr. Brett Hess Sep 2013

Examining Photocatalysis In Tio2, Daniel Jensen, Dr. Brett Hess

Journal of Undergraduate Research

Quantum mechanics is a branch of physics that is used to explain the physical properties of small molecules, nanoclusters, and other atomic systems. The principal equation used in quantum mechanics is the Schrödinger equation and its solution for a particular system tells us everything that can be known about that system’s physical properties. A major goal of our research group is to approximately solve the Schrödinger equation using computational methods. In particular we solve for the excited-state properties of the system. This then allows us to analyze optical properties in nanoclusters such as photocatalysis in TiO2.

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Applications Of Interferometry, Daniel Christensen, Dr. Dallin Durfee Sep 2013

Applications Of Interferometry, Daniel Christensen, Dr. Dallin Durfee

Journal of Undergraduate Research

Our research group is currently building a highly precise and stable atom interferometer/ atomic time standard. This is an atomic clock which, among other capabilities, will enable precision measurements of fundamental constants. Some of the long term goals of this project include time rate-of-change measurements of the fine structure constant, measurements of time dilation, and inertial force sensors.

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Modeling Magnetized, Differentially Rotating Neutron Stars, Jared Greenwald, Dr. Eric Hirschmann Sep 2013

Modeling Magnetized, Differentially Rotating Neutron Stars, Jared Greenwald, Dr. Eric Hirschmann

Journal of Undergraduate Research

There has been a tremendous research effort in trying to understand observed astrophysical phenomena. The difficulties in studying the formation of and interactions between astrophysical objects have led to the use of computational methods to solve these problems. From a theoretical point of view, one difficulty is that many of these problems have no known exact solution and therefore approximations have to be made. Computers can handle these approximations well and since they can perform many operations quickly, we can find greater accuracy by utilizing them. Once a good mathematical model is generated for some astrophysical object (say black holes, …

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Oxidation Effects On The Optical Constants Of Heavy Metals, Amy Grigg, Dr. Steve Turley Sep 2013

Oxidation Effects On The Optical Constants Of Heavy Metals, Amy Grigg, Dr. Steve Turley

Journal of Undergraduate Research

This paper examines a method that takes oxidation gradients into consideration when determining optical constants from reflectance and transmission measurements. The oxidation gradients were measured by two techniques using x-ray photoelectron spectroscopy: sputtering, where data are taken at various depths in the sample after removing the surface by sputtering; and variable angle scans, where depth information is obtained by placing the detector at several angles. X-ray photoelectron spectroscopy sputtering was found to give better results for our purposes. This method resulted in very good fits of theoretical data. For more details, see the author’s honors thesis.

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Nanoscale Construction Of A Novel Solar Cell Using Vertically-Aligned Carbon Nanotubes, David Hutchison, Dr. Robert Davis Sep 2013

Nanoscale Construction Of A Novel Solar Cell Using Vertically-Aligned Carbon Nanotubes, David Hutchison, Dr. Robert Davis

Journal of Undergraduate Research

We had planned on using the process outlined in the proposal for construction of a supercapacitor and solar cell, but decided to focus our energies on the solar cell idea since we thought we could make faster, more significant progress in that direction.

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First Observation Of Be-15, J. Snyder, T. Baumann, G. Christian, R. A. Haring-Kaye, Paul A. Deyoung, Z. Kohley, B. Luther, M. Mosby, A. Simon, J. K. Smith, A. Spyrou, S. Stephenson, M. Thoennessen Sep 2013

First Observation Of Be-15, J. Snyder, T. Baumann, G. Christian, R. A. Haring-Kaye, Paul A. Deyoung, Z. Kohley, B. Luther, M. Mosby, A. Simon, J. K. Smith, A. Spyrou, S. Stephenson, M. Thoennessen

Faculty Publications

The neutron-unbound nucleus Be-15 was observed for the first time. It was populated using neutron transfer from a deuterated polyethylene target with a 59 MeV/u Be-14 beam. Neutrons were measured in coincidence with outgoing Be-14 particles and the reconstructed decay energy spectrum exhibits a resonance at 1.8(1) MeV. This corresponds to Be-15 being unbound by 0.45 MeV more then Be-16 thus significantly hindering the sequential two-neutron decay of Be-16 to Be-14 through this state.

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The Biophysical Effects Of Deuterium Oxide On Biomolecules And Living Cells Through Open Notebook Science., Anthony Salvagno Sep 2013

The Biophysical Effects Of Deuterium Oxide On Biomolecules And Living Cells Through Open Notebook Science., Anthony Salvagno

Physics & Astronomy ETDs

This dissertation explores various effects of deuterium oxide (D2O also known as heavy water) in nature. Water is everywhere and interacts with just about everything. As such, it would be quite a daunting task to characterize every effect that water exhibits on everything in the universe. This research is a small piece of the puzzle, and provides some fundamental understanding of how water interacts with other molecules. This is done from two viewpoints: (1) the effects of heavy water on living cells and (2) the effects of heavy water on molecules. Varying concentrations of deuterium oxide were used as the …

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Relativistic Chaos: Chaos In The 1st Order Post-Newtonian Approximation Of The Three-Body Problem, Jj Campbell, Dr. David Neilsen Sep 2013

Relativistic Chaos: Chaos In The 1st Order Post-Newtonian Approximation Of The Three-Body Problem, Jj Campbell, Dr. David Neilsen

Journal of Undergraduate Research

Chaos. Some say that this word describes the world today. From the point of view of physics, they would be right. If we take “chaos” to mean an extreme sensitivity to initial conditions with exponentially diverging solutions then this world is chaotic on a number of levels, all the way from the structure of bacterial growth in a natural environment to how the solar system interacts, we are stuck in the middle of chaos. Understanding just how small changes affect the future would be very useful. Imagine what could be done if we knew exactly how a disease would spread, …

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