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Articles 1 - 30 of 317

Full-Text Articles in Physics

Y2O3 Optical Constants Between 5 Nm And 50 Nm, Joseph B. Muhlestein, Benjamin D. Smith, Margaret Miles, Stephanie M. Thomas, Anthony Willey, David D. Allred, R. Steven Turley Jan 2019

Y2O3 Optical Constants Between 5 Nm And 50 Nm, Joseph B. Muhlestein, Benjamin D. Smith, Margaret Miles, Stephanie M. Thomas, Anthony Willey, David D. Allred, R. Steven Turley

Faculty Publications

We report optical constants of e-beam evaporated yttrium oxide Y2O3 thin films as determined from angle-dependent reflectance measurements at wavelengths from 5 to 50 nm. Samples were measured using synchrotron radiation at the Advanced Light Source. The experimental reflectance data were fit to obtain values for the index of refraction and thin film roughness. We compare our computed constants with those of previous researchers and those computed using the independent atom approximation from the CXRO website. We found that the index of refraction near 36 nm is much lower than previous data from Tomiki as reported by ...


Linear Least Squares Curve Fitting, R. Steven Turley Sep 2018

Linear Least Squares Curve Fitting, R. Steven Turley

Faculty Publications

This article is a review of the theory and practice behind linear least squares curve fitting. It outlines how to find the optimal parameters to match experimental data with theory and how to estimate the uncertainty in those parameters. The article demonstrates and validates these calculations in Excel, MATLAB, Mathematica, Python, and Julia.


Cubic Interpolation With Irregularly-Spaced Points In Julia 1.0, R. Steven Turley Aug 2018

Cubic Interpolation With Irregularly-Spaced Points In Julia 1.0, R. Steven Turley

Faculty Publications

This article shows how to interpolate between regularly- or irregularly-spaced points in Julia 1.0. It has derivations of the theory behind cubic splines, and piece-wise cubic hermite polynomial interpolation. The spline interpolants are continuous and have continuous first and second derivatives. The hermite polynomial interpolants are continuous and have continuous first derivatives. Three techniques are implemented to determine the slope at the data points for the interpolation (knots). One uses the average slope of the neighboring segments. Another use the quadratic polynomial passing through the point and its two neighbors. The third, PCHIP, is similar to the first method ...


Fitting Als Reflectance Data Using Python, R. Steven Turley Apr 2018

Fitting Als Reflectance Data Using Python, R. Steven Turley

Faculty Publications

This article describes how to use the python refl library in https://bitbucket.org/steve_turley/reflectance-fitting to fit thin film reflectance data from the Advanced Light Source (ALS) at Lawrence Berkeley National Labs. It uses data taken for a thin film of aluminum capped by a thin film of aluminum fluoride on a silicon nitride substrate. The single fit in the example shown here shows the importance of taking into account the oxidation of the aluminum layer as part of the fit.


Bare Aluminum Oxidation, R. Steven Turley Nov 2017

Bare Aluminum Oxidation, R. Steven Turley

Faculty Publications

This paper computes the oxidation rate of bare evaporated aluminum thin films under high vacuum conditions and exposed to air.


Reflectance Of Xuv Light On A Two Dimensional Conducting Rough Surface, Chelsea Thangavelu Aug 2017

Reflectance Of Xuv Light On A Two Dimensional Conducting Rough Surface, Chelsea Thangavelu

Student Publications

A Fortran program is set up to solve for the reflectance of XUV light from a rough two dimensional surface, resembling experimental mirrors used to reflect XUV light. Because the roughness of the surface is on the order of magnitude of the wavelength of XUV light, our approach requires a Greene's Function instead of using traditional geometrical optics or physical optics. Our Fortran program calculates the impedance (Z) matrix which requires integration over Greene's Function at non-singular points. The Z matrix helps solve for the induced surface current J(x') at non-singular points. At singular points, the program ...


Exploring The Solvability Of The Jaynes-Cummings And Jaynes-Cummings-Like Models: Implementing Quantum Control, Austen Couvertier Aug 2017

Exploring The Solvability Of The Jaynes-Cummings And Jaynes-Cummings-Like Models: Implementing Quantum Control, Austen Couvertier

Student Publications

In this paper we aim to explore the dynamics and overall solvability of the Jaynes-Cummings \& Jaynes-Cummings-Like models. As a lens to understand these dynamics, we focused on cases where the parameters of the system were made time-dependent. All previous work on solving the dynamics of the Jaynes-Cummings models has relied heavily on the use of differential methods and setting the parameters as time-independent constants which were zero or one. To account for this, we utilized the Wei-Norman method which allowed us to analytical solve the time-dependent Hamiltonian. Through the use of this method, we can understand the more general characteristics ...


An Exploration Of Crum’S And Algebraic Crum Detection, Shae Machlus, Branton Campbell Aug 2017

An Exploration Of Crum’S And Algebraic Crum Detection, Shae Machlus, Branton Campbell

Student Publications

  1. The cooperative rigid unit modes (CRUM's) of cubic perovskite were investigated at non-special k-points using ISODISTORT and Shared Shifts Mathematica code. CRUM's were generated by the T4 irrep on the T line which confirms previously published results.
  2. The solution space of the MtM CRUM detection method was determined and compared to that of the M method. Analysis by example and by theory showed the solution spaces of both methods are identical. MtM was realized to be effectively M with a lower tolerance. An improved row reduction routine is being developed that uses an adaptable ratio-driven tolerance ...


Developing A Location Detector Using Acoustical Energy Quantities, Jacey Young Aug 2017

Developing A Location Detector Using Acoustical Energy Quantities, Jacey Young

Student Publications

In this paper, development through the use of LabVIEW for an acoustical energy quantity detector is discussed. This detector uses the quantity of sound intensity to locate the direction of a sound source in three dimensional space with relation to the center of a spherical microphone probe placed directly under a web camera. The direction and the magnitude of the sound intensity are then used to generate an arrow pointing in the direction of the sound source and position it on top the web camera's image of the surrounding area. These quantities are then also used to highlight an ...


2d Surface Creation Using Intel Mkl, R. Steven Turley Aug 2017

2d Surface Creation Using Intel Mkl, R. Steven Turley

Faculty Publications

This document illustrates how to use the Intel Math Kernel Library (MKL) to create surfaces with a given cut-off spatial frequency and rms surface height. They closely mimic typical surfaces our group has measured using atomic force microscopy (AFM).


Circular Integration Region, R. Steven Turley Aug 2017

Circular Integration Region, R. Steven Turley

Faculty Publications

This report explains how to transform a singular integration over the an arc of a circle into an integration over a unit square using various coordinate transformations include a Duffy transformation. Fortran code illustrating the algorithms is included along with unit test validations.


Magnetic Domain Morphology In [Co(4a)/Pt(7a] Thin Film, Jeremy Metzner Aug 2017

Magnetic Domain Morphology In [Co(4a)/Pt(7a] Thin Film, Jeremy Metzner

Student Publications

A collection of results for multi-layered thin films and their magnetic domains.


Using Page Method In The Two Point Method To Determine Sound Power, Christopher Reynolds Aug 2017

Using Page Method In The Two Point Method To Determine Sound Power, Christopher Reynolds

Student Publications

Sound power is the energy emitted by a sound source per unit time. It is commonly used by industries to determine the noise (unwanted sound) of machinery. There are multiple recognized standards for determining the sound power of a source. The requirements for the ISO3741 standard are tedious and strict but can produce a low standard of deviation in the results. There is another method, the Two Point method, which less strict than the standards but the standard of deviation in the results vary. This paper discusses the performance of the PAGE method employed in the Two Point method to ...


Three Ways To Stabilize An Injection Lock, Ethan Welch, Dallin Durfee, Jarom Jackson Aug 2017

Three Ways To Stabilize An Injection Lock, Ethan Welch, Dallin Durfee, Jarom Jackson

Student Publications

An injection locked laser can jump out of lock if its current or temperature drifts. By monitoring the spectra or the amplitude of the injection locked laser, we have been able to detect drifts and apply feedback to prevent injection lock from breaking.


Quantum Dot Band Gap Investigations, John Ryan Peterson Nov 2016

Quantum Dot Band Gap Investigations, John Ryan Peterson

Student Publications

Improving solar panel efficiency has become increasingly important as the world searches for cheap renewable energy. Recent developments in the industry have focused on multi-layer cells, some of which use semiconducting dyes to absorb light in place of crystalline solids. In this paper, I characterize various dyes recently synthesized for use in solar panels. These dyes contain semiconducting nanoparticles enclosed primarily by the protein ferritin to limit particle size. The band gaps were measured using either optical absorption spectroscopy or measuring the photoluminescence spectrum, depending on the type of semiconductor. The results indicate that both manganese oxide and lead sulfide ...


Development, Evaluation, And Validation Of A High-Resolution Directivity Measurement System For Played Musical Instruments, K Joshua Bodon Mar 2016

Development, Evaluation, And Validation Of A High-Resolution Directivity Measurement System For Played Musical Instruments, K Joshua Bodon

Theses and Dissertations

A high-resolution directivity measurement system at Brigham Young University has been renovated and upgraded. Acoustical treatments have been installed on the microphone array, professional-grade audio hardware and cabling have been utilized, and user-friendly MATLAB processing and plotting codes have been developed. The directivities of 16 played musical instruments and several loudspeakers have been measured by the system, processed, and plotted. Using loudspeakers as simulated musicians, a comprehensive analysis was completed to validate the system and understand its error bounds. A comparison and evaluation of repeated-capture to single-capture spherical systems was made to demonstrate the high level of detail provided by ...


Improvements To The Two-Point In Situ Method For Measurement Of The Room Constant And Sound Power In Semi-Reverberant Rooms, Zachary R. Jensen Mar 2016

Improvements To The Two-Point In Situ Method For Measurement Of The Room Constant And Sound Power In Semi-Reverberant Rooms, Zachary R. Jensen

Theses and Dissertations

The two-point in situ method is a technique for measuring the room constant of a semi-reverberant room and the sound power of a source in that room simultaneously using two measurement positions. Using a reference directivity source, where the directivity factor along any given axis of the source has been measured, one is able to use the Hopkins-Stryker equation to measure both the room constant and the sound power level of another source rather simply. Using both numerical and experimental data, it was found that by using generalized energy density (GED) as a measurement quantity, the results were more accurate ...


Measurement Of The Yb I 1S0-1P1 Transition Frequency At 399 Nm Using An Optical Frequency Comb, Michaela Kleinert, M. E. Gold Dahl, Scott D. Bergeson Jan 2016

Measurement Of The Yb I 1S0-1P1 Transition Frequency At 399 Nm Using An Optical Frequency Comb, Michaela Kleinert, M. E. Gold Dahl, Scott D. Bergeson

Faculty Publications

We determine the frequency of the Yb I 1S0-1P1 transition at 399 nm using an optical frequency comb. Although this transition was measured previously using an optical transfer cavity [D. Das et al., Phys, Rev. A 72, 032506 (2005)], recent work has uncovered significant errors in that method. We compare our result of 751 526 533.49 ± 0.33 MHz for the 174Yb isotope with those from the literature and discuss observed differences. We verify the correctness of our method by measuring the frequencies of well-known transitions in Rb and Cs, and by demonstrating ...


Construction Of A 408 Nm Laser System For Use In Ion Interferometry, Lawrence Archibald Dec 2015

Construction Of A 408 Nm Laser System For Use In Ion Interferometry, Lawrence Archibald

Theses and Dissertations

This work reports on the construction of a 408 nm laser system designed to drive stimulated Raman transitions between the F = 4 and F = 5 2 S 1/2 states of 87 Sr + using the 2 P 3/2 state as the intermediate state. This laser system will be used as part of a 87 Sr + ion interferometer. This work also includes a discussion of relevant theory describing the interaction of the ions and laser, along with a calculation of the transition rates as a function of laser power and detuning.


Information Behaviors Of Nuclear Scientists At Korea Atomic Energy Research Institute, Youngchoon Chun, Jiho Yi, Jung-Ran Park, Sangki Choi Oct 2015

Information Behaviors Of Nuclear Scientists At Korea Atomic Energy Research Institute, Youngchoon Chun, Jiho Yi, Jung-Ran Park, Sangki Choi

Journal of East Asian Libraries

The goal of the study was to analyze the information use behaviors of researchers in the science and technology domain. A survey and interviews were conducted targeting nuclear scientists at the Korea Atomic Energy Research Institute. Study results indicate that the nuclear scientists mainly use the Institute library/information center and Internet portal/search engines during information acquisition. Easy access to information, accuracy, currency and cost are the most critical factors in selecting and obtaining information. The most frequently used database for executing research is the Institute’s electronic library (NUCLIS21) followed by the Citation Index SCOPUS. The results of ...


Comparing Theory And Experiment For Analyte Transport In The First Vacuum Stage Of The Inductively Coupled Plasma Mass Spectrometer, Matthew R. Zachreson Jul 2015

Comparing Theory And Experiment For Analyte Transport In The First Vacuum Stage Of The Inductively Coupled Plasma Mass Spectrometer, Matthew R. Zachreson

Theses and Dissertations

The inductively coupled plasma mass spectrometer (ICP-MS) has been used in laboratories for many years. The majority of the improvements to the instrument have been done empirically through trial and error. A few fluid models have been made, which have given a general description of the flow through the mass spectrometer interface. However, due to long mean free path effects and other factors, it is very difficult to simulate the flow details well enough to predict how changing the interface design will change the formation of the ion beam. Towards this end, Spencer et al. developed FENIX, a direct simulation ...


A Feasibility Study Of Photometric Reverberation Mapping With Meter-Class Telescopes, Carla June Carroll Jun 2015

A Feasibility Study Of Photometric Reverberation Mapping With Meter-Class Telescopes, Carla June Carroll

Theses and Dissertations

For the past several decades, mass estimates for supermassive black holes hosted by active galactic nuclei (AGN) have been made with the reverberation mapping (RM) technique. This methodology has produced consistent results and has been used to establish several relations that link the characteristics of the host galaxy to the mass of the central black hole. Despite this success, there are less than 50 AGN with black hole masses derived from RM. This low number is generally attributed to the difficulties in coordinating large blocks of telescope time for making simultaneous photometric and spectroscopic observations. Spectroscopic observations also generally require ...


Characterization Of Order-Disorder Phase Transition Temperature For Select Nanoparticles, Gregory J. Sutherland Jun 2015

Characterization Of Order-Disorder Phase Transition Temperature For Select Nanoparticles, Gregory J. Sutherland

Theses and Dissertations

A method was found for creating ordered nanoparticles whose size and theoretical order-disorder temperature are ideal for study in the TEM. Specifically FePt, NiPt, FeNiPt and AuCu nanoparticles were studied. We were able to show how a nanoparticle's size affects its order-disorder temperature (Tod). When the particles were around 6 nm in diameter there was a shift downward of the Tod of 10-15 percent compared to the bulk. While particles around 10 nm in diameter experienced a downward shift of 0-6 percent compared to the bulk. One can approximate that particles less than 10-15 nm in diameter would show ...


Simulations Of Electron Trajectories In An Intense Laser Focus For Photon Scattering Experiments, Grayson J. Tarbox Mar 2015

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 ...


Radio Emission Toward Regions Of Massive Star Formation In The Large Magellanic Cloud, Adam Johanson Mar 2015

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 ...


Strongly-Coupled Plasmas Formed From Laser-Heated Solids, M. Lyon, Scott D. Bergeson, G. Hart, M. S. Murillo Jan 2015

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 Jan 2015

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 ...


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 Jan 2015

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 ...


Algebraic Semi-Classical Model For Reaction Dynamics, Tim Glenn Wendler Dec 2014

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 ...


Towards Stronger Coulomb Coupling In An Ultracold Neutral Plasma, Mary Elizabeth Lyon Jul 2014

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 ...