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Four-Wave Mixing With Orbital Angular Momentum Transfer, Hana Warner 2020 William & Mary

Four-Wave Mixing With Orbital Angular Momentum Transfer, Hana Warner

Undergraduate Honors Theses

We explore the conservation of orbital angular momentum (OAM) in the four-wave mixing (FWM) process in hot rubidium vapor. Since most modern communication systems send data in pulses corresponding to bits, we can use OAM to encode more information in each pulse by assigning structure to each signal. Furthermore, because FWM can be used to generate entangled photon pairs, we can use this process to bring enhanced signal security. We experimentally studied FWM with a wide range of Laguerre-Gaussian modes and their superpositions and observed OAM transfer from the probe field to a generated Stokes field. By studying the output ...


Development Of Wearable Sensors For Gait Analysis, Jorden Smyth 2020 William & Mary

Development Of Wearable Sensors For Gait Analysis, Jorden Smyth

Undergraduate Honors Theses

In an ongoing experiment being conducted at The Williamsburg Landing by The Center for Balance and Aging Studies (CBAS), gait analysis is being performed on senior citizens in order to identify gait characteristics that are predictive of an increased likelihood to fall. This thesis describes the design and analysis of wearable sensors meant to assist the Williamsburg Landing study by increasing the efficiency and breadth of data collection. These sensors collect distance data from the foot to the ground over the course of multiple steps and return an approximation of the average step cycle for the subject. From my analysis ...


Development And Upgrade Of A Laser Cooling And Trapping System Of Ultracold Potassium Atoms, Bennett Atwater 2020 William & Mary

Development And Upgrade Of A Laser Cooling And Trapping System Of Ultracold Potassium Atoms, Bennett Atwater

Undergraduate Honors Theses

This thesis describes work to improve the apparatus that cools and loads potassium atoms onto the atom chip. This work consists of two main thrusts: a laser trap translator to help cool and load atoms onto the atom chip and a temperature stabilization system for the lasers that are used to laser cool potassium atoms. The current iteration of the beam translator has the ability to vertically translate a beam ±4.5 mm relative to its incident height. The translator has been shown to not alter the spatial profile of the beam through interference or obstruction. The translator’s rotation ...


Studying And Correcting For Helicity-Correlated False Asymmetries In The Prex Ii And Crex Experiments, Carrington Metts 2020 William & Mary

Studying And Correcting For Helicity-Correlated False Asymmetries In The Prex Ii And Crex Experiments, Carrington Metts

Undergraduate Honors Theses

The goal of the PREx II and CREx experiments are to determine the size of the neutron distribution in 208Pb and 48Ca, respectively. Because these isotopes have a large discrepancy in between the number of neutrons and protons, theoretical models predict that some of the neutrons will arrange themselves in a “skin” on the nucleus’s surface. Prior results from the PREx I experiment confirmed the existence of the neutron skin in 208Pb. All of the mentioned experiments employ the technique of parity-violating electron scattering. Electron-nucleus weak interactions are dominated by electron-neutron scattering, which is an order ...


Computational Simulations Of Temperature-Dependent Dynamics In Type Ii Superconductors Using A Material Specific Formulation Of Ginzburg Landau Theory, Aiden Harbick 2020 William & Mary

Computational Simulations Of Temperature-Dependent Dynamics In Type Ii Superconductors Using A Material Specific Formulation Of Ginzburg Landau Theory, Aiden Harbick

Undergraduate Honors Theses

Superconducting Radio Frequency (SRF) cavities play a fundamental role in particle accelerators. Efficient operation depends on expelling magnetic flux from the cavity, and any residual flux that remains trapped after cooling below the critical temperature can have a significant impact on performance. Experimental evidence suggests that material defects as well as cooling protocols can have a strong impact on subsequent performance. To better understand these phenomena, we use time-dependent Ginzburg-Landau theory implemented as finite-element simulations. We adapt the theory to allow spatial variation of material-specific parameters along with realistic temperature dependencies. We report on numerical experiments for different configurations of ...


Conservation Of Orbital Angular Momentum In Degenerate Four-Wave Mixing Via Rubidium Vapor, Kangning Yang 2020 William & Mary

Conservation Of Orbital Angular Momentum In Degenerate Four-Wave Mixing Via Rubidium Vapor, Kangning Yang

Undergraduate Honors Theses

We present an experimental platform which can generate quantum-correlated beams with Orbital Angular Momentum (OAM) via degenerate Four-Wave Mixing (FWM) in Rubidium vapor. We further investigated the conservation of OAM before and after FWM by performing LG mode decomposition using interferometer. To compare our experimental result with theoretical prediction, we simulated a simplified version of our set up. Moreover, we used this toy model to study the conservation of radial and angular intensity profile through changing parameters limited by our set up. In general, we found that FWM preserves most information consisted in OAM, but has a rather loose control ...


Gait Characterization Using Computer Vision Video Analysis, Martha T. Gizaw 2020 College of William and Mary

Gait Characterization Using Computer Vision Video Analysis, Martha T. Gizaw

Undergraduate Honors Theses

The World Health Organization reports that falls are the second-leading cause of accidental death among senior adults around the world. Currently, a research team at William & Mary’s Department of Kinesiology & Health Sciences attempts to recognize and correct aging-related factors that can result in falling. To meet this goal, the members of that team videotape walking tests to examine individual gait parameters of older subjects. However, they undergo a slow, laborious process of analyzing video frame by video frame to obtain such parameters. This project uses computer vision software to reconstruct walking models from residents of an independent living retirement ...


Studies In Seop Hyperpolarized 3he: Measuring Ko And The Spatial Dependence Of Alkali Polarization, Michael Cairo 2020 William & Mary

Studies In Seop Hyperpolarized 3he: Measuring Ko And The Spatial Dependence Of Alkali Polarization, Michael Cairo

Undergraduate Honors Theses

3He is an isotope of helium whose nucleus is composed of two protons and one neutron. The proportion of atoms whose spins are pointed along the same direction in a volume of 3He gas is known as the polarization. This study entails two experiments in the field of 3He polarimetry concerned with measuring the polarization of a 3He cell and reducing the uncertainty associated with it. 3He cells are full of gaseous 3He, along with alkali metal vapors, K and Rb in our case. The polarization of a 3He cell can be measured ...


An Overview Of Lasers And Their Applications, Luis Cristian Giovanni Guerrero 2020 California Polytechnic State University, San Luis Obispo

An Overview Of Lasers And Their Applications, Luis Cristian Giovanni Guerrero

Physics

This paper is an overview of lasers and their applications. The fundamentals of laser operation are covered as well as the various applications of advanced laser systems. The primary focus is to highlight some of the technological advancements made possible by lasers in the last half-century.


Design And Construction Of A Computer Controlled Astronomical Spectropolarimeter, Jacob Marchio 2020 University of Maine

Design And Construction Of A Computer Controlled Astronomical Spectropolarimeter, Jacob Marchio

Honors College

A theoretical description of a simple optical train, modulated signal based spectropolarimeter is discussed. The design includes, after the telescope optical tube (in this case, a 9.25” Schmidt Cassegrain), a rotating quarter waveplate (compensator), a fixed linear polarizer (analyzer), and transmission grating of 100l/mm, with a ZWO ASI290mm astronomical camera. The practical constraints on implementing such an instrument are discussed, and the construction of the spectropolarimeter is detailed, including the necessary optics, optomechanics, and electromechanics. The rotation and recording of the rotating compensator is facilitated by a motorized connection with proportional feedback control, and the uncertainty in measuring ...


Construction Of A Hyperspectral Imager Using 3d-Printed And Off-The-Shelf Components, Joshua Moorhouse 2020 University of Arkansas, Fayetteville

Construction Of A Hyperspectral Imager Using 3d-Printed And Off-The-Shelf Components, Joshua Moorhouse

Mechanical Engineering Undergraduate Honors Theses

The Arkansas Center for Space and Planetary Sciences is working in collaboration with the Mechanical Engineering department to create a relatively cheap and modifiable hyperspectral imager. It is constructed using 3D-printed and off-the-shelf components from Edmund Optics and Amazon. The iteration created in this paper delivers spectrograms in the visible spectrum. The long-term goals of the camera are to create hyperspectral images from these spectrograms and to advance the imager into the infrared and near-infrared spectra. This imager is being developed to be used in the Arkansas Center for Space and Planetary Sciences environmental test chambers to further the scientific ...


The Parity-Violating Asymmetry In The N→Δ Transition At Low Q2, Thamraa A. Alshayeb 2020 Louisiana Tech University

The Parity-Violating Asymmetry In The N→Δ Transition At Low Q2, Thamraa A. Alshayeb

Doctoral Dissertations

Qweak has used the parity violating asymmetry to test the Standard Model (SM) by constantly flipping helicity states of a longitudinally polarized electron beam that scatters in the unpolarized LH2 target. The main focus of the Qweak experiment at Jefferson Lab was the recently published determination of the proton’s weak charge. In order to make corrections to the measured asymmetry at low 𝑄 2 due to inelastically scattered electrons, dedicated measurements were made of the parity violating asymmetry in the N→∆ transition at two different beam energies.

The measured inelastic asymmetries are used to extract the low energy constant ...


Secular Changes In Atmospheric Turbidity Over Iraq And A Possible Link To Military Activity, Alexandra Chudnovsky, A. Kostinski 2020 Tel Aviv University

Secular Changes In Atmospheric Turbidity Over Iraq And A Possible Link To Military Activity, Alexandra Chudnovsky, A. Kostinski

Michigan Tech Publications

We examine satellite-derived aerosol optical depth (AOD) data during the period 2000-2018 over the Middle East to evaluate the contribution of anthropogenic pollution. We focus on Iraq, where US troops were present for nearly nine years. We begin with a plausibility argument linking anthropogenic influence and AOD signature. We then calculate the percent change in AOD every two years. To pinpoint the causes for changes in AOD on a spatial basis, we distinguish between synoptically "calm" periods and those with vigorous synoptic activity. This was done on high-resolution 10 km AOD retrievals from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor ...


Phytoplankton Community Composition In The Surface Ocean: Methods For Detection Using Optical Measurements, Pigment Concentrations, And Flow Cytometry, Alison P. Chase 2020 University of Maine

Phytoplankton Community Composition In The Surface Ocean: Methods For Detection Using Optical Measurements, Pigment Concentrations, And Flow Cytometry, Alison P. Chase

Electronic Theses and Dissertations

Phytoplankton are microscopic photoautotrophs living in the surface ocean waters and help support all life on earth via photosynthetic production of oxygen. Thousands of species make up the bulk phytoplankton community, and the spatial and temporal distribution of different types of phytoplankton has relevance for many ocean ecosystem questions including marine food web dynamics, and carbon flux and sequestration. Methods to detect phytoplankton community composition (PCC) on the vast scale of the global ocean require estimates of PCC from remote platforms, namely earth-observing satellites. The use of satellite data to observe and interpret PCC in the surface ocean requires significant ...


Electrical And Chemical Characterization Of A Helium-Air Non-Thermal Atmospheric Pressure Plasma Jet, Adam Zandani 2020 Seton Hall University

Electrical And Chemical Characterization Of A Helium-Air Non-Thermal Atmospheric Pressure Plasma Jet, Adam Zandani

Seton Hall University Dissertations and Theses (ETDs)

Plasma is one of the most complicated, yet promising fields in physics due to its high efficiency and multitude of crucial applications such as biological sterilization, polymer modification, surface treatments, etching, agriculture, and facilitation of selective catalytic processes to name a few. With these advantages, mysteries still remain. With this in mind, in order to accurately gauge the total influence of the plasma applied in various processes, understanding what is being produced and how the production occurs is vital. To understand this, optical emission spectroscopy was used to gauge how the species generated are influenced by operation parameters such as ...


An Investigation Of Diode Failure, Nicholas James Adams 2020 California Polytechnic State University, San Luis Obispo

An Investigation Of Diode Failure, Nicholas James Adams

Physics

Solar electricity can be used to cheaply cook food and charge electronic devices. We investigate the viability of using diodes as heating elements for insulated solar electric cooking (ISEC). In addition, information on designing and constructing ISEC compatible phone chargers and rechargeable LED lighting systems is included.


Measurements Of Fast Alpha Decays In The 100sn Region, Ian Connor Cox 2020 University of Tennessee, Knoxville

Measurements Of Fast Alpha Decays In The 100sn Region, Ian Connor Cox

Chancellor’s Honors Program Projects

No abstract provided.


Changes In The Scattering Phase Shifts For Partial Waves Of Ultracold Particles At Different Energies, Kaaviyan Faezi 2020 University of Connecticut

Changes In The Scattering Phase Shifts For Partial Waves Of Ultracold Particles At Different Energies, Kaaviyan Faezi

Honors Scholar Theses

At low energies, scattering phase shifts, the difference in phases between the incoming and outgoing spherical waves in scattering, for different partial waves follow a similar pattern. The phase shift curves, which are a function of the angular momentum quantum number for different scattering energy, obtain resonances after reaching their maxima, and as energy is increased, these resonances become smaller and eventually disappear. Using numerical methods involving the use of Chebyshev polynomials, we solve the wave equation for a scattering potential to obtain the radial equation. From the radial equation we then find the scattering phase shift for a particular ...


Investigating The Stability Of Observed Low Semi-Major Axis Exoplanetary Systems With Hypothetical Outer Planets Using The Program Mercury6, Kendall Butler 2020 University of Maine

Investigating The Stability Of Observed Low Semi-Major Axis Exoplanetary Systems With Hypothetical Outer Planets Using The Program Mercury6, Kendall Butler

Honors College

This project investigates the stability of observed planetary systems, and whether this stability remains in the presence of additional outer planets. This made use of the program Mercury6, an n-body integrator that computes the changes in planetary orbits over time. The Systems HD 136352, GJ 9827, and HD 7924 were studied with initial conditions taken from the available observational data. This information was curated using the online NASA Exoplanet archive of confirmed exoplanets. With these initial conditions, Mercury6 computed the changing planetary orbits of each system for 5 million years. For each of these systems, a single outer planet, which ...


Applying Cluster Analysis To Student Responses From Energy Surveys For Identification Of Commonalities In Their Understanding, Arianna Giguere 2020 University of Maine

Applying Cluster Analysis To Student Responses From Energy Surveys For Identification Of Commonalities In Their Understanding, Arianna Giguere

Honors College

Energy is a complicated model that has been developed to describe matter to matter interactions. Since energy can be challenging to define, there are inconsistencies among even teachers and physicists in how they define the concept. It is no wonder that students themselves carry misconceptions and confusions. While it may be difficult to teach, an understanding of energy from a young age is essential for the future of technology, climate change, and scientific discoveries. Middle school students in Maine are required to learn about energy transformation, conservation, and forms, and from 2011-2018, researchers at the University of Maine administered multiple ...


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