Physics Commons^™

Analysis Of Turbulent Flow Behavior In Helicopter Rotor Hub Wakes, Forrest Mobley

Masters Theses

The rotor hub is one of the most important features of all helicopters, as it provides the pilot a means for controlling the vehicle by changing the characteristics of the main and tail rotors. The hub also provides a structural foundation for the rotors and allows for the rotor blades to respond to aerodynamic forces while maintaining controllability and stability. Due to the inherent geometry and high rate of rotation, the rotor hub in its current form acts a large bluff body and is the primary source of parasite drag on the helicopter, despite its relatively small size. The rotor …

Transverse Energy Analysis In Small Collision Systems, Alexander L. Aukerman

Masters Theses

Heavy Ion Collisions performed in the LHC at Cern are capable of generating a new phase of nuclear matter known as the Quark Gluon Plasma. In addition to running heavy ion collisions, the detectors dedicated to studying the QGP perform collisions utilizing smaller collision systems for the sake of comparing key measurements associated with the creation of a QGP. The transverse energy of the particles generated from the collision is one such key measurement. For the sake of comparison an analysis is performed on the transverse energy measurements taken from proton-proton collisions.

Meta-Heuristic Optimization Techniques For The Production Of Medical Isotopes Through Special Target Design, Cameron Ian Salyer

Masters Theses

Medical isotopes are used for a variety of different diagnostic and therapeutic purposes Ruth (2008). Due to recent newly discovered applications, their production has become rapidly more scarce than ever before Charlton (2019). Therefore, more efficient and less time consuming methods are of interest for not only the industry’s demand, but for the individuals who require radio-isotope procedures. Currently, the primary source of most medical isotopes used today are provided by reactor and cyclotron irradiation techniques, followed by supplemental radio-chemical separations Ruth (2008). Up until this point, target designs have been optimized by experience, back of the envelope calculations, and …

Enigma - Ongoing Development Towards Novel Beta-Decay Spectroscopy Station At Isolde, Philipp Wagenknecht

Masters Theses

Beta decay and collinear laser spectroscopy are proven efficient tools to study nuclear structure far from stability. Two areas of significance are investigations into nuclear deformation and shape coexistence, as well as delayed neutron emissions used in nuclear energy applications. This contribution presents the ongoing development towards a novel beta-decay spectroscopy station for the VITO experiment at CERN’s radioactive ion beam facility ISOLDE. The setup will utilize both collinear laser spectroscopy and beta-decay spectroscopy to measure the energy and spin-parities of the ground and excited states of radioactive beams. Initial designs of the support structure, magnetic field, and detector array …

Accelerating Dynamical Density Response Code On Summit And Its Application For Computing The Density Response Function Of Vanadium Sesquioxide, Wileam Y. Phan

Masters Theses

This thesis details the process of porting the Eguiluz group dynamical density response computational platform to the hybrid CPU+GPU environment at the Summit supercomputer at Oak Ridge National Laboratory (ORNL) Leadership Computing Center. The baseline CPU-only version is a Gordon Bell-winning platform within the formally-exact time-dependent density functional theory (TD-DFT) framework using the linearly augmented plane wave (LAPW) basis set. The code is accelerated using a combination of the OpenACC programming model and GPU libraries -- namely, the Matrix Algebra for GPU and Multicore Architectures (MAGMA) library -- as well as exploiting the sparsity pattern of the matrices involved in …

Calculation And Modeling Of The Neutron’S Magnetic Moment, Abhyuday Sharda

Masters Theses

This thesis presents the current state of neutron magnetic moment calcu- lations. It details the development of calculations through history. It also delves into an experiment measuring the neutron magnetic moment. It ex- plores other methods by which calculations can be improved to get a better/ more accurate number. The conclusion is that there are still a lot of areas unexplored in context of the calculation of neutron magnetic moment and areas relevant to be worked upon are detailed.

Machine Learning Applications For Waveform Analysis, Micah R. Cruz

Masters Theses

Since the later 20th century, the search for physics beyond the Standard Model (BSM) has been paramount to many nuclear and particle physicists. Neutron and nuclear beta decay experiments provide one avenue to search for evidence of BSM physics by contributing to the unitarity check of the Cabibbo-Kobayashi-Maskawa matrix. Many of these experiments detect neutron decay products as digitized waveforms. As computing power increases and novel algorithms are developed, it is compelling to investigate machine learning methods as an analytic tool for such waveform data. These methods can allow for very fast data exploration techniques, and if pseudodata is available …

An Explicit Asymptotic Approach Applied To Neutrino-Electron Scattering In The Neutrino Transport Problem, Aaron Michael Lackey - Stewart

Masters Theses

This thesis presents results of explicit asymptotic calculations applied to neutrino-electron collisions in the neutrino transport problem; a problem that is generally solved using implicit methods when simulating core collapsed supernovae. It is shown that the explicit asymptotic method provides stable solutions to these stiff systems of equations while also yielding comparative accuracy and time stepping to standard implicit treatments such as Backward Euler, Fixed Point Iteration, and Anderson Accelerated Fixed Point. Because implicit methods are found to be less efficient for large systems of stiff, coupled equations, these results could help cut costs in solving this problem while also …

Phase Transitions And The Casimir Effect In Neutron Stars, William Patrick Moffitt

Masters Theses

What lies at the core of a neutron star is still a highly debated topic, with both the composition and the physical interactions in question. In this thesis, we made assumptions regarding the composition to further study the interactions of matter during the transition phases. These phases, also known as nuclear pasta, come from the unique physical conditions which occur within neutron stars. We examine the feasibility of the Casimir effect manifesting during these phases, as well as the effects it would have on the total energy of the system. We find that the crust-core transition cannot support the proper …

Characterization Of Reactor Background Radiation At Hfir For The Prospect Experiment, Blaine Alexander Heffron

Masters Theses

This work describes an investigation of the background radiation present at the High Flux Isotope Reactor (HFIR) on behalf of the PROSPECT collaboration. The PROSPECT experiment is designed to make a precision measurement of the antineutrino spectrum at HFIR and search for sterile neutrinos. Temporal and spacial variation of neutron and gamma backgrounds at the experiment site for the PROSPECT detector are measured in order to determine if the reactor correlated radiation will contribute a significant background to the inverse beta decay signal. Knowledge of spacial background variation will also be used to inform the design of a local shield …

Probing Pulse Structure At The Spallation Neutron Source Via Polarimetry Measurements, Connor Miller Gautam

Masters Theses

The Fundamental Neutron Physics Beamline (FNPB) at Spallation Neutron Source is used to probe fundamental forces via cold neutrons. The beamline's latest experiment is probing the hadronic weak interaction through the capture of polarized cold neutrons on ³He nuclei. While the strong nuclear force is dominant in this interaction, a weak signal can be observed in the parity violating momentum asymmetry in the reaction products. As the asymmetry measurement requires both neutron spin states, a means of controlling the neutron spin is required. In order to alternate the spins, a radio frequency spin rotator was installed for the experiment. …

Development Of Nuclear Underground Engineered Test Surrogates For Technical Nuclear Forensics Exploitation, Robert Boone Gilbreath

Masters Theses

A method for formulation and production of Nuclear UnderGround Engineered Test Surrogates (NUGETS) based on notional improvised nuclear device (IND) detonations in an underground environment analogous to the Nevada National Security Site (NNSS) is presented. Extensive statistical analyses of precursory geochemical and geophysical characteristics are combined with an augmented surrogate debris cooling technique and predictive IND contributions from the ORIGEN Fallout Analysis Tool. Precursory and resultant elemental compositions, cooling curve calculations, and visual comparison of NUGETS to genuine underground debris are reported. Application of NUGETS methodology to future studies in urban, underground post-detonation technical nuclear forensic (TNF) analysis is suggested.

Development Of Microfluidic Platforms For Studies Of Cellular Organization In Escherichia Coli, Anna Dawn Jennings

Masters Theses

Traditionally, bacteria cells have been imaged on agarose pads allowing them to grow in steady conditions for only a few doubling times. To understand the cellular organization in bacteria, tools are needed that allow the observation of log-phase cells for many generations. In recent years, several microfluidic platforms have been designed that allow microscopic imaging of bacteria for over one hundred generations. One of the most promising approaches has been the so-called mother machine design where bacteria grow in small dead-end channels all connected to a large main channel, which is used to flow fresh nutrients to the cells and …

Optimization Of The Nedm Experiment, Patrick Rogers

Masters Theses

The Neutron Electric Dipole Moment (NEDM) experiment is an upcoming experiment at ORNL to measure the size of an electric dipole moment inside of the neutron. This is being done to probe CP asymmetries that could give rise to a matter dominated universe. The experiment will utilize a nuclear reaction that outputs scintillation light in a manner that depends on the alignment of the spins of the reactant particles. This light will be detected and used to measure the NEDM. The amount of light collected for measurement will impact the accuracy of the results; the more photons collected the better …

Development, Analysis, And Optimization Of A Swirl-Promoting Mean Flow Solution For Solid Rocket Motors, Andrew Steven Fist

Masters Theses

This work demonstrates and analyses a new flow candidate for describing the internal gaseous motion in simulated rocket motors. The fundamental features of this solution include the conservation of key system properties also incorporated in the classic Taylor-Culick (TC) system (i.e. inviscid, axisymmetric, steady and rotational properties), while allowing for the development of a swirling velocity component. The work compares the new solution to the development and formulation of the classic TC system, ultimately identifying that both the new and classic solutions are special cases of the Bragg-Hawthorne equation. Following this development, the text then explores the development of energy-optimized …

Experimental Study On The Production Of Negative Ion Copper Clusters And Applications, Ran Chu

Masters Theses

At the Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Laboratories (ORNL), we investigated the formation, production and potential application of negative-ion copper clusters using mass distributions of negative-ion copper clusters obtained by bombarding various copper samples with Cs ions. The Cu samples – in very large mass-selected clusters Cu (e.g. n=54) – included natural Cu, isotopically enriched copper-63 and copper-65, and electroformed ultra-clean Cu. Mass spectra of negative copper cluster produced by Cs sputter source size up to 50 are shown for the first time.

Three main features were observed for all four copper samples: the intensity …

Correction To Luminosity Measurement For The Pixel Luminosity Telescope At Cms, Krishna Thapa

Masters Theses

The search for and detailed study of new particles and forces with the Compact Muon Solenoid (CMS) detector at the Large Hadron Collider (LHC) of CERN is fundamentally dependent on the precise measurement of the rate at which proton-proton collisions produce any particles, the so-called luminosity. Therefore, a new detector, the Pixel Luminosity Telescope (PLT), dedicated to measure the luminosity at high precision was added to the CMS experiment in 2015. It measures the inclusive charged particle production from each collision of proton bunches in the LHC. Additional charged particles which are observed by the instrument but produced from sources …

Improving Ventricular Catheter Design Through Computational Fluid Dynamics, Sofy Hefets Weisenberg

Masters Theses

Cerebrospinal fluid (CSF) shunts are fully implantable medical devices that are used to treat patients suffering from conditions characterized by elevated intracranial pressure, such as hydrocephalus. In cases of shunt failure or malfunction, patients are often required to endure one or more revision surgeries to replace all or part of the shunt. One of the primary causes of CSF shunt failure is obstruction of the ventricular catheter, a component of the shunt system implanted directly into the brain's ventricular system. This work aims to improve the design of ventricular catheters in order to reduce the incidence of catheter obstruction and …

Installation And Alignment Of The N3he Experiment, Eric Lee Plemons

Masters Theses

The n3He experiment is designed to probe the hadronic weak interaction by measuring the parity violating asymmetry between the spin of incoming neutrons and the momentum of outgoing protons following the nuclear break up of a helium three upon absorbing a neutron. Cold neutrons from the SNS are first polarized then allowed to impact a target chamber filled with helium three where the reaction occurs. Energetic particles resulting from the nuclear breakup ionize the helium three gas and are thereby detected as currents by an array of signal wires within the target chamber. In order to make a statistics limited …

Strontium Monoxide Measurements In Methane-Air Flames, Bobby J. Wimberly

Masters Theses

The spectroscopy of alkaline earth metal compounds has been an area of active research for several decades. This is at least in part stimulated by the application of these compounds to practical areas ranging from technology to medicine. The use of these compounds in the field of pyrotechnics was the motivation for a series of flame emission spectroscopy (FES) experiments with strontium containing compounds. Specifically, strontium monoxide (SrO) is studied as a candidate radiator for the diagnostic of methane-air flames.

SrO emissions have been observed in flames with temperatures in the range of 1200-1600-K for two compounds: strontium hydroxide and …

The Cms Pixel Luminosity Telescope Browser Interface, Mark Miller Foerster

Masters Theses

The search for and detailed study of new particles and forces with the Compact Muon Solenoid (CMS) detector at the Large Hadron Collider (LHC) of CERN is fundamentally dependent on the precise measurement of the rate at which proton-proton collisions produce any particles, the so-called luminosity. For the discovery of the Higgs candidate in 2012 the relative precision of this quantity was about 2.5%. To be able to observe deviations from Standard Model predictions for decay rates of this particle and others which can hint to new phenomena the targeted luminosity uncertainty is about 1%. Therefore, a new device, the …

Diatomic Carbon Measurements With Laser-Induced Breakdown Spectroscopy, Michael Jonathan Witte

Masters Theses

In this thesis, investigation of well-known carbon Swan spectra is of primary interest. Combustion processes and/or explosion of hydrocarbon fuels cause occurrence of the Swan band system that originates from diatomic carbon. Physical characteristics of low-temperature stars and the interstellar medium can also reveal the Swan bands. The diatomic carbon molecule shows that its lowest rotational levels are sensitive to temperature variation, and higher rotational levels are sensitive to the surrounding gas density and the radiation field. In addition, carbon is a crucial element for life and is the 4th most abundant element; therefore, it is important to ascertain accurately …

Mass Table Calculations With Nuclear Density Functional Theory, Noah Watson Birge

Masters Theses

To better understand nuclei and the strong nuclear force, it is useful to analyze global nuclear properties and trends across the nuclear chart. To this end, we utilized Nuclear Density Functional Theory with Skyrme Energy Density Functionals in conjunction with high-performance computing to perform large-scale mass table calculations for even-even nuclei. Using the binding energy, pairing gap, root-mean-square radius, and deformation data from these tables we were able to analyze the two-proton and two-neutron drip lines, neutron skin depth, two-proton radioactivity, and the effect of nuclear deformation on mass filters. We used numerous energy density functionals to assess the statistical …

Phase Dynamics Of Locset Control Methodology, Brendan Neschke

Masters Theses

Single-mode fiber amplifiers produce diffraction-limited beams very efficiently. Maximum beam intensity requires that an array of these amplifiers have their beams coherently combined at the target. Optical path differences and noise adversely affect beam quality. An existing closed loop phase control methodology, called the locking of optical coherence by single-detector electronic-frequency tagging (LOCSET), corrects phase errors in real time by electronically detecting path length differences and sending signals to lithium niobate phase adjusters. Broadening the line-width using “jitter” of the input signal can increase the output power of an individual amplifier by suppressing nonlinearity. The system dynamics of LOCSET are …

Laser-Induced Breakdown Spectroscopy For Analysis Of High Density Methane-Oxygen Mixtures, Matthew Dackman

Masters Theses

The applicability of laser-induced breakdown spectroscopy (LIBS) toward greater than atmospheric density combustion diagnostics is examined. Specifically, this involves ascertaining the feasibility of measuring chemical equivalence ratios directly from atomic emission spectra at high density. The need for such measurement arises from the desire to quantify real time, localized combustion performance in weakly mixed flows. Insufficiently mixed flows generally result in unwanted byproducts, possess the propensity for overall combustion instability, and are increasingly likely to experience localized flame extinction.

We simulate methane/oxygen combustion in ambient pressures ranging 1 to 4 atmospheres, demonstrating these results to be analogous to what would …

Design And Model Of The Frame For Hagrid (Hybrid Array Of Gamma Ray Detectors), Santiago Munoz

Masters Theses

Transfer reactions in inverse kinematics have provided critical information in the study of exotic nuclei. However, transfer reactions with charged particles suffer from poor resolution. The measurement of gamma-rays offers several advantages: they provide not only good resolution in measurements but also other information about the nuclei like lifetimes of unstable states. The combination of these two methods would be the ideal situation to gather information about nuclear structure.

HAGRiD, which stands for The Hybrid Array of Gamma Ray Detectors, is a LaBr3(Ce) [lanthanum bromide crystal with a cerium activator] scintillation array to measure gamma rays from transfer reactions and …

Thick Target Yield Of Th-229 Via Low Energy Proton Bombardment Of Th-232, Justin Reed Griswold

Masters Theses

Actinium-225 is one of the more effective radioisotopes used in alpha radioimmunotherapy. Due to its ten-day half-life, it is more efficient to create its precursor, ²²⁹Th [Thorium-229] (t_1/2[half-life] = 7932 ± 55 years). In this work, ²²⁹Th was produced via 40 MeV [Mega electron Volts] proton bombardment of a thick ²³²Th [Thorium-232] target. The irradiation took place at the Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Lab (ORNL). The target, consisting of 23 stacked natural thorium foils (137 mg/cm² [milligrams per square centimeter] each), was irradiated with 50 nA [nanoamps] of …

Radiation-Induced Radicals In Polyurea-Crosslinked Silica Aerogel, Benjamin Michael Walters

Masters Theses

Free radicals are atoms or molecules with an odd number of electrons in an outer shell. Since electrons typically occur in pairs, this leaves one electron that is unpaired. In seek of another electron to pair with, free radicals react with and steal electrons from neighboring molecules, which then become free radicals themselves. This can start a chain reaction, cascading into large scale damage.

Ionizing radiation can tear through molecules, just as bullets can tear through things that we see. If free radicals can be detected, and seen to increase in a material upon radiation exposure, this can indicate molecular …

The Isotope Effect On Proton Conduction And Glass Transition In Phosphoric Acid, Maximilian Ferdinand Heres

Masters Theses

Hydrogen fuel cells combine hydrogen and oxygen to create water and electricity. Polymer electrolyte membranes (PEM) make up barriers within the fuel cell allowing only protons to pass through, while keeping other components separate. Many PEM contain phosphoric acid (PA) as a building block due to its excellent proton conducting properties. Improved ionic conductivity in PEM can lead to the development of better, more efficient fuel cells.

While ionic conductivity in PA at high temperatures is extensively characterized, the low temperature dynamics are not so well explored. Below the glass transition, molecular motion is frozen and proton motion is forced …

Structure Analysis Of Sn Bilayer Films On Si (111), Weisong Tu

Masters Theses

Chemical doping is a well-established method for controlling the electronic properties of bulk semiconductors and, e.g, complex oxide materials. In this process, dopant atoms are located at substitutional lattice locations, from where they introduce free charge carriers to the host material. These carriers greatly improve the electrical conductivity of the host material and can even induce an insulator-metal transition at high doping levels. Dopants, however, also introduce scattering centers that are detrimental to conductivity, especially in low-dimensional systems such as nanowires and ultrathin films. These problems can be overcome by using a modulation doping approach in which the dopant atoms …