Physical Sciences and Mathematics Commons^™

Quantum Dot Band Gap Investigations, John Ryan Peterson

Student Works

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 …

Modeling Of Acoustic Resonators And Resonator Systems For Use In Passive Noise Control, Matthew Franklin Calton

Theses and Dissertations

Acoustic resonators, such as the Helmholtz and quarter-wave resonator, can be used to attenuate unwanted noise in an enclosed space. Classical formulations can be used to approximate resonator performance for a given resonator configuration, but may lack sufficient accuracy for some applications. This research aims to improve the analytical characterization of resonators to provide better correlation to experimental results. Using higher-order approximations and proper end corrections, more accuracy can be obtained in calculating the impedance and resonance frequency of a single resonator, which will then carry over into the overall configuration of the model. The impedance of a system of …

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 …

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 …

Optically Detected Magnetic Resonance Of Silicon Vacancies In Sic: Predicting Resonance Of Cylindrical Cavities, Kyle Miller, John Colton

Journal of Undergraduate Research

Optically Detected Magnetic Resonance is one method of performing Electron Spin Resonance (ESR) on a material. ESR is used to determine the electron spin lifetime of a material, an important parameter for use in quantum computing. Resonant cavities are conducting containers that are frequently used in ESR to create a strong magnetic field near the sample. As such it is valuable to design a resonant cavity and predict its resonant frequency. Cylindrical cavities modified with dielectric resonators (DRs) are viable for such experiments.

Exploring The Weak Mach Reflection Regime, Kevin Leete, Dr. Kent Gee

Journal of Undergraduate Research

When a shock wave reflects off a rigid surface with certain combinations of incident shock strength and angle, a Mach reflection can occur. This is when portions of the incident and reflected waves merge to create a stronger shock called a Mach stem that travels parallel to the reflecting surface. This phenomenon has been studied extensively for two extreme cases: large outdoor explosions and small, laboratory experiments of weak shocks. The purpose of this project was to design and execute an outdoor experiment where this phenomenon could be observed by microphones as well as high speed video imaging to detect …

High Resolution Shock Capturing On Gpus, Forrest Glines, David Neilsen

Journal of Undergraduate Research

This research project concerns the development simulation code to confirm neutron star mergers as the progenitors of Short Hard Gamma Ray Bursts. Short Hard Gamma Ray Bursts (SHGBs) are short (less than 2 second) high energy bursts that we observe with satellites. Their exact cause has not yet been confirmed, but they are believed to be created by the merging of either two neutron stars or a neutron star falling into a black hole. Neutron stars are ultra dense, highly magnetic, and compact stars at the end of their evolution. In a binary system the stars lose angular momentum to …

Determining The Size Of A Light Source Using The Hanbury Brown And Twiss Effect, Adam Kingsley, Dallin Durfee

Journal of Undergraduate Research

In 1956, Hanbury Brown and Twiss (HBT) published a paper¹ on a method of determining the angular size of a star by comparing the intensities gathered from two detectors. They used this effect by using two photomultiplier tubes and by increasing the distance between them, saw a drop in the correlation between the currents. Because the correlations are made by the interference at the detectors but only the intensity is measured, the effect is sometimes referred to as intensity interferometry.

The idea arose to use the HBT effect to teach undergraduates various principles of light in a lab setting. …

Phase Matching In Laser Generated Harmonics, David Squires, Justin Peatross

Journal of Undergraduate Research

In this mentored research project, we investigated how intense laser light is scattered by samples of gas. In particular, we measured light scattered in non-phase-matched directions perpendicular to the laser beam.

According to classical phase matching, the intensity of light scattered from a sample depends on whether the sample is best approximated as a continuous medium or a collection of discrete emitters (Figure 1). In the former case, as the angle between the phase-matching direction and the radiated harmonic approaches π/2 radians, the intensity of that radiated harmonic light approaches 0. In the latter case, the light intensity reaches …

Porous Cantilevers As Chemical Sensors, Steven Noyce, Robert Davis

Journal of Undergraduate Research

Many chemical sensing methods rely on the binding mechanism of the analyte to create a measurable response, making it difficult to create new sensors quickly, but resonant sensors require only that an analyte be bound and rely on the resulting change in mass to obtain a measurement. Solid resonant microcantilevers, or small vibrating fixed-free beams, are a type of resonant sensor that have shown extremely high sensitivities in vacuum environments. The sensitivity of these cantilevers, however, decreases greatly in fluid environments such as air or water due to fluid damping. We propose that porous microcantilever sensors offers both a ten …

Measuring Frequency Noise For Use In Preventing Mode Hops In Extended Cavity Diode Lasers, Mckinley Pugh, Dallin Durfee

Journal of Undergraduate Research

Diode lasers are useful in physics because they are relatively cheap and robust, they are available in a number of wavelengths, and they are tunable. However, because diode lasers have large bandwidths compared to atomic resonances, a reflection grating is added outside the laser. This creates the extended cavity in extended cavity diode lasers (ECDLs) and forces the lasers to operate at a narrower line width, one acceptable for use in atomic physics. Unfortunately, because the ECDL has many factors trying to control the wavelength of the laser (e.g. temperature, current, grating angel and position) small changes in the lasers …

Systematic Analysis Of Nonlinearities In Complex Models, Alexander Shumway, Mark Transtrum

Journal of Undergraduate Research

Mathematical models are ubiquitous in science. Many models are nonlinear in the parameters and may have dozens to thousands of parameters and make hundreds to thousands of predictions. Analysis and application of these models is thus theoretically complicated and computationally expensive.

The standard method of model analysis is a model-by-model approach that relies on the intuition of expert researchers. Recent research, however, has shown that many models—known as sloppy models—are statistically similar, despite coming from widely varied fields⁴. This suggests the possibility of developing a theory of modeling in place of relying on expert intuition. Our research …

Dual Species Calcium And Ytterbium Magneto Optical Trap, Alexander Erickson, Scott Bergeson

Journal of Undergraduate Research

One area of particular interest in modern physics research is creating a viable fusion system for sustainable energy. Fusion occurs when a high energy plasma is manipulated in such a way that small atoms collide together, combining to create larger atoms and releasing tremendous amounts of harvestable energy. However, there are many theoretical, mathematical, and practical roadblocks to creating a stable fusion experiment. One practical limitation and one mathematical limitation are as follows: practically, much of the energy used to create a fusion-grade plasma ends up in the kinetic energy of the electrons and is lost to the experiment; mathematically, …

Reflectometry Of Aluminum Thin Films In The Vacuum Ultraviolet, Benjamin Smith, R. Steven Turley

Journal of Undergraduate Research

Vacuum Ultraviolet (VUV) is a range of light on the electromagnetic spectrum corresponding to wavelengths from 40 – 280 nm. VUV photons have too much energy to see visibly and are blocked completely by atmosphere. This wavelength range, however, shows promise for applications in space-based exoplanet research telescopes. Specifically, the chemical fingerprints that this light contains can tell us about the composition and formation of exoplanet atmospheres.

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 …