Digital Commons Network^™

Constraints On Parton Distribution Functions Imposed By Hadronic Experiments, Boting Wang

Physics Theses and Dissertations

The theoretical uncertainties of the Large Hadron Collider (LHC) observables are decreasing with the increasing statistics of the LHC experiments, and it is becoming more and more important to reduce the uncertainties in the knowledge of the nucleon structure. The latest LHC high-energy experiments, future experimental proposals, and computational tools are expected to enhance the knowledge of the nucleon structure. However, the global analysis that assesses their impact on Parton Distribution Functions (PDFs) knowledge is computationally expensive due to the corresponding large size of data. I developed a new approach that can make a quick preliminary evaluation to help the …

Jet Cross-Sections At 8 Tev With The Alice Experiment., Andrew Castro

Doctoral Dissertations

Hadronic jets are created in the earliest stages of a high energy collision due to a hard interaction between two partons. ALICE (A Large Ion Collider Experiment) is one of the main detectors located at the Large Hadron Collider. By using the ALICE Time Projection Chamber and Electromagnetic Calorimeter inclusive jets can be reconstructed over a wide kinematic range. Measuring jets in proton-proton collisions serves as a baseline measurement for understanding energy loss in the nuclear matter and the processes by which quarks form into hadrons. Inclusive jet cross-sections and their ratios were measured in this thesis using the 8 …

Massive Elementary Particles In The Standard Model And Its Supersymmetric Triplet Higgs Extension, Keping Xie

Physics Theses and Dissertations

In this dissertation, we focus on massive elementary particles in the Standard Model and its supersymmetric triplet Higgs extension.

In the first part, we start with a review of electroweak (EW) sector in the Standard Model. Motivated by nonzero neutrino masses, we consider triplet scalars in addition to the Standard Model. The vacuum expectation values of scalar triplets are strongly constrained by the $\rho$ parameter, extracted from electroweak precision measurements. Therefore, we introduce a custodial symmetry to weaken this constraint and obtain the well-known Georgi-Machacek (GM) Model. The GM model still requires fine-tuning to satisfy the $\rho$ parameter constraint. It …

A Search For Boosted Low Mass Resonances Decaying To The Bb̅ Final State And Produced In Association With A Jet At √S = 13 Tev With The Atlas Detector, Matthew Feickert

Physics Theses and Dissertations

A search in the high momentum regime for new resonances, produced in association with a jet, decaying into a pair of bottom quarks is presented using an integrated luminosity of 80.5 fb^-1 of proton-proton collisions at center-of-mass energy √s = 13 TeV recorded by the ATLAS detector at the Large Hadron Collider. The search was performed for low mass resonances, including the Standard Model Higgs boson and leptophobic Z' dark matter mediators, in the mass range of 100 GeV to 200 GeV. For the Standard Model Higgs boson, the observed signal strength is μH = 5.8 ± 3.1 (stat.) …

A Likelihood Search For Low-Mass Dark Matter Via Inelastic Scattering In Supercdms, Daniel Jardin

Physics Theses and Dissertations

An abundance of evidence suggests that most of the Universe is composed of nonluminous matter. This "dark matter” is believed to be a new elementary particle and experiments around the world are attempting to directly detect rare collisions with terrestrial detectors.

The properties of dark matter have yet to be identified, thus efforts are ongoing to explore a range of possible masses and interaction cross-sections. For the latter, experiments can increase exposure by scaling up the detector mass and operating for a longer time. To search for dark matter with less mass than a nucleon, new technologies and analysis techniques …

Kinematics And Dynamics Of Lead Climbing, Arik B. Espineli

Honors Projects

The goal of this research is to gain a better understanding of the kinematics and dynamics involved with lead climbing. Digital accelerometers, load sensors, and slow motion cameras were used to conduct both small and large scale testing of different factors of that might effect a climber and belayer during lead climbing. Rope elasticity and belayer movement were the two factors that were looked at for this research. Small scale testing was done using rigid masses, cords with different levels of elasticity, and a pulley system to simulate anchor points. From the small scale testing it was found that a …

Quantifying Complex Systems Via Computational Fly Swarms, Troy Taylor

Senior Theses

Complexity is prevalent both in natural and in human-made systems, yet is not well understood quantitatively. Qualitatively, complexity describes a phenomena in which a system composed of individual pieces, each having simple interactions with one another, results in interesting bulk properties that would otherwise not exist. One example of a complex biological system is the bird flock, in particular, a starling murmuration. Starlings are known to move in the direction of their neighbors and avoid collisions with fellow starlings, but as a result of these simple movement choices, the flock as a whole tends to exhibit fluid-like movements and form …

New Methodologies For Examining And Supporting Student Reasoning In Physics, John C. Speirs

Electronic Theses and Dissertations

Learning how to reason productively is an essential goal of an undergraduate education in any STEM-related discipline. Many non-physics STEM majors are required to take introductory physics as part of their undergraduate programs. While certain physics concepts and principles may be of use to these students in their future academic careers and beyond, many will not. Rather, it is often expected that the most valuable and longlasting learning outcomes from a physics course will be a repertoire of problem-solving strategies, a familiarity with mathematizing real-world situations, and the development of a strong set of qualitative inferential reasoning skills.

For more …

Exploring The Electrical Properties Of Twisted Bilayer Graphene, William Shannon

Senior Theses

Two-dimensional materials exhibit properties unlike anything else seen in conventional substances. Electrons in these materials are confined to move only in the plane. In order to explore the effects of these materials, we have built apparatus and refined procedures with which to create two-dimensional structures. Two-dimensional devices have been made using exfoliated graphene and placed on gold contacts. Their topography has been observed using Atomic Force Microscopy (AFM) confirming samples with monolayer, bilayer, and twisted bilayer structure. Relative work functions of each have been measured using Kelvin Probe Force Microscopy (KPFM) showing that twisted bilayer graphene has a surface potential …

Transferring Power Through A Magnetic Couple, Nickolas Cruz Villalobos Jr.

Senior Theses

Properties of several working magnetic coupled rotors have been measured and their performance compared to theoretical models. Axial magnetic couplers allow rotors to work within harsh environments, without the need for seals, proper alignment, or overload protection on a motor. The influence of geometrical parameters, such as distance from the center of the rotors, polarity arrangement, and the number of dipole pairs were experimentally tested. These results can be used to improve rotor designs, to increase strength and efficiency.

Manufacturing And Testing The Permanent Magnet Linear Motor, Renjie Kang

Senior Theses

Controlled mechanical motion is vital in many useful applications in technology. Among them, linear motors have advantages over traditional rotating motors. In this work, we built a permanent magnet linear motor to test and measure its energy efficiency. A maximum 29% total energy efficiency, and 67% energy transfer rate, were detected. In addition, a C-shape support structure was added to the moving part in order to increase the moving accuracy. The tests show that, with the support structure, the fluctuation in the vertical direction decreases significantly, but the friction of the system slightly increases.

The Poetic Function Of Imagination: The Parallel Process Of Poiêsis, Angela Carlson

Expressive Therapies Capstone Theses

In the advent of Postmodernism, modern approaches to understanding the nature of things is being put into question. As the gap between objective and subjective realms of experiences is narrowing, there is an increased need for a more artful approach to science. This paper serves as my attempt to promote the field of Expressive Arts Therapy (ExATh) as a mode of poetic science for understanding the experience of ‘Being’ in the world. Through a critical review of the semantic development of the ancient Greek concepts poiêsis, noêsis, and aisthêsis, the imagination is identified as a function of alêthaic revealing, …

Beam-Spin Asymmetry Of Exclusive Coherent Electroproduction Of The Π0 Off 4he, Frank Thanh Cao

Doctoral Dissertations

To understand the partonic structure of nucleons in nuclei, measuring the beam spin asymmetry (BSA) from exclusive processes is important to get at the so-called Generalized Parton Distributions (GPDs) that describe the partons’ behavior inside the nucleon. In particular, BSA in Deeply Virtual Meson Production (DVMP) can offer valuable constraints on the transverse GPDs which are not accessible with other exclusive processes. Furthermore, DVMP measurements on bound nucleons can offer insights into structure modification due to the nuclear environment.

The interpretation of this bounded nucleon DVMP on nuclear targets rests on the assumption of factorization and that higher-order effects are …

D-Terms In Bosonic And Fermionic Systems, Jonathan Hudson

Doctoral Dissertations

The most fundamental information about a particle is contained in the matrix elements of its energy-momentum tensor (EMT): the mass and spin. But the EMT contains more information than that. Equally important yet far less known is the D-term and with it, the information contained in the spatial components of the EMT. The D-term and the spatial components of the EMT show in detail how the strong forces inside the nucleon balance to form a bound state and provides unique insights on the nucleon structure. The goal of this thesis is to contribute to a better understanding of the physics …

Quartic Metamaterials: The Inverse Method, Perturbations, And Bulk Optical Neutrality, Thomas Mulkey

Honors College Theses

A primary goal of photonics is designing material structures that support predetermined electromagnetic field distributions. We have developed an inverse method to determine material parameters for a quartic metamaterial from six desired plane waves. This work inspired us to study how perturbations to the parameters can result in optical neutrality.

Manipulating Light: Creating A Biomimetic Photonic Crystal Material Inspired By The Chameleon, Love L. Richburg

Honors Theses

The purpose of this project is to create a chameleon-inspired biomimetic material using guanine crystals and polydimethylsiloxane (PDMS) to form a tunable photonic crystal and then characterize the material. The method for developing this material is to first synthesize a photonic crystal made of a guanine microsphere lattice. Then embed the guanine lattice in PDMS. Since PDMS is an elastomer, it can be stretched to adjust the spacing between the guanine crystals. This should allow for the photonic crystal to be adjusted similarly to the way that the chameleon adjusts the photonic crystal in its skin by changing the spacing …

Electric Form Factor Of The Neutron From Asymmetry Measurements, Richard Frederick Obrecht Jr

Doctoral Dissertations

The overwhelming majority of visible mass in the universe is composed of protons and neutrons, collectively known as nucleons, which are arguably the most important strongly interacting systems to study. A nucleon may naively be thought of as a composite object built out of three non-interacting sub-objects, known as quarks, in the large energy limit; however, the structure of the nucleon is much more complicated, and consequently far richer, than a simple valence-quark picture. There are sea quarks in addition to valence quarks that interact strongly via the exchange of gluons resulting in a complex vacuum structure, and the collective …

The Magnetocaloric Effect & Performance Of Magnetocaloric Materials In A 1d Active Magnetic Regenerator Simulation, Daniel Nicholas Bayer

Browse all Theses and Dissertations

Active magnetic regenerators (AMRs) operate according to the magnetothermal phenomenon known as the magnetocaloric effect (MCE), and are at the forefront of magnetic cooling technology. AMR simulations have been shown to be useful tools in predicting the performance of different magnetocaloric materials (MCMs) without the need to develop a physical prototype. In a search to determine the set of operational parameters which would maximize MCM performance, a 1D simulation of an AMR device has been developed in Matlab. Gadolinium, the most well-documented MCM, is used as a benchmark material to study the effects of varying certain operational parameters such as …

Improved Momentum Spread For Precision Physics Experiments Using Wedges, Nick Amato

Graduate Research Theses & Dissertations

High precision experiments have become key in the search for physics beyond the Standard Model. One measurement that can be made in order to expand our knowledge of the Standard Model is the precise measurement of the magnetic dipole moment (MDM) of the muon. In order to perform this precise measurement of the MDM of muons, the storage of particles with a precisely known momentum in a highly uniform magnetic field is required.

This thesis is focused on how one may use a wedge of energy absorbing material and the optical parameters of an accelerator lattice to improve upon the …

Development Of Physics Based Machine Learning Algorithms, Rob Jennings

Master’s Theses

In this study, a baseball pitch was examined to try to understand its behavior, and make a predictive model of it. A baseball pitch was tested experimentally with a wind tunnel and modeled computationally with COMSOL CFD software. Five input variables (spin rate, sting angle, seam orientation: Y axis, seam orientation: Z axis, and air velocity) were controlled, with force in three axes recorded as outputs. The experimental and computational results were examined and seen to be interdependent for all input variables. Experimental and computational data were both insufficient for predicting system behavior. Experimental data collection would have required an …

The Temporal Conatus And The Problem Of Motion From Eternity, David Harmon

Electronic Theses and Dissertations

Spinoza’s theory of persistence is articulated through the conatus (EIp7) and the ratio of motion and rest (EIIp13). Section I explores Spinoza’s usage of “motion,” and illustrates that the conatus is essentially temporal. From this claim and Spinoza’s conception of eternity, the problem arises. I explain this as a contradiction between Natura naturata and Natura naturans. Section II features an evaluation of the potential acosmist solution and reveals how it contradicts other Spinozistic commitments. I construct an alternative solution in Section III. Temporal passage is not an adequate idea for Spinoza. However, Spinoza considers duration to be a feature of …

Development Of Nonlocal Green-Kubo Formalism With Applications To Coupled Heat And Mass Transport, Kevin Fernando

Honors Undergraduate Theses

Nonlocal equations for coupled heat and mass transport are developed within the Green-Kubo formalism. Nonlocal thermal transport in Lennard-Jones solids is computed to establish the existence of semi-ballistic transport. Deviations from the diffusive theory are shown by comparing the Fourier transform of the response function from the nonlocal theory to that of the diffusive one. It is shown that the deviations from the local theory correspond to acoustic phonons, whose frequency dependence gives rise to the observed deviations from the local theory.

What Causes Black Holes To Spin?, Mac B. Selesnick

Senior Projects Spring 2019

Black holes are recently at the cutting edge of cosmological and astrophysical research. Both experiment and theory are leading to surprising conclusions on the physical properties of black holes and their affects on space and time. In this project, I set out to explore the origin and mechanics of a black hole's spin, that is, its internal angular momentum. What causes a black hole to spin in the first place is rich and nuanced. In order to make this project accessible and focused I explore the process of a minor merger, a collision between two black holes, one large and …

The Invisible Sun: Building A Radio Interferometer Telescope, Isobel Curtin

Senior Projects Spring 2019

When we think of astronomy, we often associate the word implicitly with observing astronomical bodies with our own eyes, or from a signal collected in the visible light range. However, there is more information we can collect from these bodies when observing them using other kinds of light, unseen to the naked eye. Radio astronomy is an important tool in an astronomer’s toolkit, and can help us image hidden parts of the universe. Recently, radio astronomy was used to directly image a black hole in the center of a nearby galaxy for the first time!

This projects aims to further …

Modelling Potential Fluctuations In Double Layer Graphene Systems As A Periodic Oscillation In Electron Density & Its Effect On Coulomb Drag, Ryan Bogucki

Williams Honors College, Honors Research Projects

An expression for the drag transresistivity in a graphene double layer system exhibiting potential fluctuations modelled as a periodic oscillation in electron density is derived. Our model starts from the Coulombic interaction and we derive the correlation between a sinusoidal fluctuation in electron density in the first layer and the induced electron density in the second layer. Previous models in the literature have employed an arbitrary correlation between each layer’s electron density, and the model presented is the first attempt in the literature to explicitly derive this correlation. Recent experiments have found that the drag transresistivity in graphene double layers …

Practical Chaos: Using Dynamical Systems To Encrypt Audio And Visual Data, Julia Ruiter

Scripps Senior Theses

Although dynamical systems have a multitude of classical uses in physics and applied mathematics, new research in theoretical computer science shows that dynamical systems can also be used as a highly secure method of encrypting data. Properties of Lorenz and similar systems of equations yield chaotic outputs that are good at masking the underlying data both physically and mathematically. This paper aims to show how Lorenz systems may be used to encrypt text and image data, as well as provide a framework for how physical mechanisms may be built using these properties to transmit encrypted wave signals.

Investigation Of Narrow Bipolar Events In Mississippi Thunderstorms, Sampath Asiri Bandara

Electronic Theses and Dissertations

In the first part of the study FA and Log-RF data were used to examine low-altitude (<8.0 km) negative NBEs (NNBEs) to see how many -CG flashes were initiated by NNBEs. Out of 686 -CG flashes only 33 (5%) flashes were initiated by an NNBE. These NNBEs occurred at an average altitude of 6.2 km had average amplitude (range-normalized amplitude to 100 km) of 0.4 V/m and had average VHF (Log-RF) power of 130 W. Since the low-altitude NNBEs were substantially weaker than positive NBEs that initiate intracloud (IC) flashes it is hypothesized that -CG flashes are easier to initiate than IC flashes. The second part of the study investigated the properties of 201 positive NBEs (+NBEs). The +NBEs were classified in two ways: into Types A-D [Karunarathne et al. 2015] and into three different groups: Isolated Not-isolated and IC flash-initiator or INBE [Wu et al. 2014]. The average VHF (Log-RF) power of NBEs within the A-D categories were 1.9 4 9.8 and 13.2 kW respectively while the powers for the Isolated Not-isolated and INBE categories were 10.1 4 and 10.1 kW respectively. The third study considered 34 NBEs that occurred close in space and time to each other: 13 pairs of NBEs one group of three +NBEs and one group of five +NBEs. The NBEs were overlaid on radar data of the parent thunderstorms. The data indicate that the individual NBEs in each group initiated in separate intense electric field regions of small extent rather than in a single large-scale electric field region. This dissertation investigates Narrow Bipolar Events (NBEs) which are a type of short-duration (10- 30 µs) lightning discharge. The study primarily used data from NBEs collected in 2016 at seven sensor sites within 50 km of Oxford Mississippi USA. Each sensor site had three electromagnetic antennas called Fast Antenna (FA) dE⁄dt and Log-RF with bandwidths of 0-2.5 MHz 0-1.0 MHz and 186-192 MHz respectively. NBEs are often isolated from other lightning events in thunderclouds but they sometimes initiate negative cloud-to-ground (-CG) and intracloud (IC) lightning flashes or they can occur during these flashes.

Finding Darkness: A Case Study On The Light Polluting Effects Of Regis University, Ryan Abo

Regis University Student Publications (comprehensive collection)

The author outlines techniques Regis University could employ to make lighting infrastructure safer, healthier, and more pleasing while still being dark sky friendly.

The Impact Of Hii Regions On The Interstellar Medium Of Our Galaxy, Matteo Luisi

Graduate Theses, Dissertations, and Problem Reports

The interstellar medium (ISM) of our Galaxy contains low-density diffuse ionized gas known as the warm ionized medium (WIM). O- and B-type stars emit large amounts of ionizing radiation and it is believed that a fraction of this radiation escapes from their fully ionized HII regions and into the ISM where it is responsible for maintaining the ionization of the WIM. Here we aim to better understand how the radiation produced by OB stars is able to leak from the HII regions, how the radiation field changes during this process, and how the radiation affects the ambient ISM. Using Green …

Evaluation Of X-Ray Spectroscopic Techniques For Determining Temperature And Density In Plasmas, Theodore Scott Lane

Graduate Theses, Dissertations, and Problem Reports

Temperature and density measurements of plasmas are important for understanding various phenomena. For example, equations of state, most scaling arguments for Inertial Confinement Fusion and laboratory astrophysics all rely upon accurate knowledge of temperature and density. Spectroscopy is a non-invasive technique to measure these quantities. In this work we establish a new spectroscopic technique by using it to determine temperature. We also compare and contrast the capability of two codes, PrismSPECT and ATOMIC, to infer electron density from experimentally acquired spectra via Stark broadening.

We compare and contrast the capability of isoelectronic line ratios and inter-stage line ratios in an …