Other Physics Commons^™

An Implantable Mosfet Dosimeter Modified To Act As A Fiducial Marker, Joseph S. Dick

Dissertations and Theses (Open Access)

In external beam radiation therapy, it is imperative that the prescribed dose is administered to the correct location and in the correct amount. Though several ex vivo methods of quality assurance are currently employed to achieve this goal, verifying that the correct dose is received within the patient in situ is impossible without the capability of measuring dose inside the patient. Recently, a method of measuring dose delivered within the patient has been developed, an implantable MOSFET dosimeter. This dosimeter is implanted within the patient and records the dose received. Since the dosimeter is implanted in the patient, it could …

Benchmarking And Implementation Of A New Independent Monte Carlo Dose Calculation Quality Assurance Audit To Ol For Clinical Trials, Scott E. Davidson

Dissertations and Theses (Open Access)

Introduction Commercial treatment planning systems employ a variety of dose calculation algorithms to plan and predict the dose distributions a patient receives during external beam radiation therapy. Traditionally, the Radiological Physics Center has relied on measurements to assure that institutions participating in the National Cancer Institute sponsored clinical trials administer radiation in doses that are clinically comparable to those of other participating institutions. To complement the effort of the RPC, an independent dose calculation tool needs to be developed that will enable a generic method to determine patient dose distributions in three dimensions and to perform retrospective analysis of radiation …

Dynamic Chemical Shift Imaging For Image-Guided Thermal Therapy, Brian A. Taylor

Dissertations and Theses (Open Access)

Magnetic resonance temperature imaging (MRTI) is recognized as a noninvasive means to provide temperature imaging for guidance in thermal therapies. The most common method of estimating temperature changes in the body using MR is by measuring the water proton resonant frequency (PRF) shift. Calculation of the complex phase difference (CPD) is the method of choice for measuring the PRF indirectly since it facilitates temperature mapping with high spatiotemporal resolution. Chemical shift imaging (CSI) techniques can provide the PRF directly with high sensitivity to temperature changes while minimizing artifacts commonly seen in CPD techniques. However, CSI techniques are currently limited by …

The Usage Of Smartphones In The Calculation Of Relativistic Time Dilation Effects At Meager Velocities, Leland Gregory

Physics

The theories of special and general relativity postulate that events are not simultaneous for different observers, and that different observer's times tick at different rates depending on relative velocity and the magnitude of the gravitational field they are in. This project seeks to design a program for use with smartphones that will calculate this change in time, in real time, and keep track of the discrepancies in time experienced between the observer and a stationary point on the surface of the earth.

Cryogenic Refrigeration For Quantum Voltage Standards, Jeffrey Power

Physics

Currently the world maintains the voltage standard using a Josephson junction which makes use of the properties of superconductors and quantum tunneling. Current technology requires liquid He to cool the Josephson junctions to ~4 K to allow them to function as superconductors. He (l) is expensive and price is geographically dependent. Here we investigated using a cryocooler, modeled after a Gifford-McMahon Refrigerator, that could run on 120V (or a standard outlet) and used gaseous He as the working fluid –a less geographically dependent and inexpensive alternative to He (l). We found that indeed a standard outlet gaseous He compressor could …

Investigation Of Track-Cluster Matching Vs Track-Cell Matching In The Alice Detector At Cern, Kevin Coulombe

Physics

The ALICE (A Large Ion Collider Experiment) Experiment is a detector that is one of four stationed at the CERN Large Hadron Collider. The goal of ALICE is to investigate the properties of the quark-gluon plasma, a new form of matter which only existed during the first microsecond of the Universe. ALICE measures the aftermath of the collision of two lead ions. Some information detected is the trajectory of the particles traveling through the tracking detectors and energy deposited in the calorimeters. Both the tracks and energy are required to determine the identities of the various particles as they travel …

Computing Hydrogen Energetic Neutral Atom (Ena) Losses For Nasa's Ibex Using 3d Models, Eric Zirnstein

Honors Capstone Projects and Theses

No abstract provided.

Commissioning An Anthropomorphic Spine And Lung Phantom For Remote Dose Verification Of Institutions Participating In Rtog 0631, Douglas F. Caruthers

Dissertations and Theses (Open Access)

The RPC developed a new phantom to ensure comparable and consistent radiation administration in spinal radiosurgery clinical trials. This study assessed the phantom’s dosimetric and anatomic utility. The ‘spine phantom’ is a water filled thorax with anatomy encountered in spinal radiosurgery: target volume, vertebral column, spinal canal, esophagus, heart, and lungs. The dose to the target volume was measured with axial and sagittal planes of radiochromic film and thermoluminescent dosimeters (TLD). The dose distributions were measured with the radiochromic film calibrated to the absolute dose measured by the TLD. Four irradiations were administered: a four angle box plan, a seven …

Range Adaptive Proton Therapy For Prostate Cancer, Adam D. Melancon

Dissertations and Theses (Open Access)

Purpose: The rapid distal falloff of a proton beam allows for sparing of normal tissues distal to the target. However proton beams that aim directly towards critical structures are avoided due to concerns of range uncertainties, such as CT number conversion and anatomy variations. We propose to eliminate range uncertainty and enable prostate treatment with a single anterior beam by detecting the proton’s range at the prostate-rectal interface and adaptively adjusting the range in vivo and in real-time.

Materials and Methods: A prototype device, consisting of an endorectal liquid scintillation detector and dual-inverted Lucite wedges for range compensation, was designed …

An Analysis Of The Quasi Biennial Oscillation, Ozone And Thermal Damping, Kevin Jauregui

Physics

No abstract provided.

Upgrade To The Pierre Auger Cosmic Ray Observatory's Lidar System, Emily B. Petermann

Department of Physics and Astronomy: Dissertations, Theses, and Student Research

The Pierre Auger Cosmic Ray Observatory currently operates four elastic lidar systems in order to characterize the atmospheric aerosol content above the observatory. The atmospheric information gained by the lidar system is then used in the calibration of the observatory’s four fluorescence detectors. Currently the four lidars in operation are unable to accurately determine the aerosol content below a distance of 1 km. A project is currently underway to upgrade the current lidar system by adding an additional detector to each of the existing lidar systems. The considered designs for this upgrade and the initial results from the upgrade prototype …

Construction And Enhancement Of Stereo Vacuum Tube Amplifier With Precision Machined Enclosure, Nikolaus (Nik) Glazar

Physics

The purpose of this project was to build a high fidelity tube amplifier from a kit, and machine a beautiful enclosure to house the electronics. Improvements were made to the circuit, and the amplifier was then tested for audio performance.

Thoracic Radiotherapy Treatment Planning With Cine Pet/Ct, Adam C. Riegel

Dissertations and Theses (Open Access)

Purpose: Respiratory motion causes substantial uncertainty in radiotherapy treatment planning. Four-dimensional computed tomography (4D-CT) is a useful tool to image tumor motion during normal respiration. Treatment margins can be reduced by targeting the motion path of the tumor. The expense and complexity of 4D-CT, however, may be cost-prohibitive at some facilities. We developed an image processing technique to produce images from cine CT that contain significant motion information without 4D-CT. The purpose of this work was to compare cine CT and 4D-CT for the purposes of target delineation and dose calculation, and to explore the role of PET in target …

Analysis Of An All-Optical Sbs Avalanche Detector, D. Walker, M. Steiner, Armen Gulian

Mathematics, Physics, and Computer Science Faculty Articles and Research

Seeding Brillouin scattering with a sufficiently efficient source of coherent phonons has the potential to produce energy-sensitive photon detectors. Based on this idea, we propose and analyze some possible designs for such a detector.

Gamma-Ray Spectroscopy: Meteorite Samples And The Search For 98tc, Kristopher L. Merolla

Physics

The focus of this project is low-count-level gamma-ray spectroscopy on meteorite samples in search of a particular isotope of Technetium (98Tc), which according to stellar theory, should be present in the universe. The spectral lines for 99Tc have, however, been observed in S-, M-, and N- type stars, which makes finding 98Tc created naturally a possibility, and thus a search can be justified.

Integration Of Electronic And Optical Techniques In The Design And Fabrication Of Pressure Sensors, Ivan Padron

Dissertations

Since the introduction of micro-electro-mechanical systems fabrication methods, piezoresistive pressure sensors have become the more popular pressure transducers. They dominate pressure sensor commercialization due to their high performance, stability and repeatability. However, increasing demand for harsh environment sensing devices has made sensors based on Fabry-Perot interferometry the more promising optical pressure sensors due to their high degree of sensitivity, small size, high temperature performance, versatility, and improved immunity to environmental noise and interference. The work presented in this dissertation comprises the design, fabrication, and testing of sensors that fuse these two pressure sensing technologies into one integrated unit. A key …

Relationship Between Photospheric Magnetic Fields And Coronal Activities, Changyi Tan

Dissertations

Coronal emission comes in two forms, a steady component where the corona is heated to million degrees and a much hotter transient component of solar flares. Both components are known to be related to the evolution of surface magnetic fields. This dissertation studies the evolution of photospheric magnetic fields and flow fields and their relation to the properties of these two coronal emission components.

The key issue in the study of the steady coronal emission is the coronal heating problem: how the corona is heated to millions of degrees while the underlying solar photosphere is only a few thousand degrees. …

A Hybrid Particle-Continuum Method For Hydrodynamics Of Complex Fluids, Alejandro Garcia, A. Donev, J. B. Bell, B. Alder

Faculty Publications

A previously developed hybrid particle-continuum method [J. B. Bell, A. Garcia, and S. A. Williams, Multiscale Model. Simul., 6 (2008), pp. 1256–1280] is generalized to dense fluids and two- and three-dimensional flows. The scheme couples an explicit fluctuating compressible Navier–Stokes solver with the isotropic direct simulation Monte Carlo (DSMC) particle method [A. Donev, A. L. Garcia, and B. J. Alder, J. Stat. Mech. Theory Exp., 2009 (2009), article P11008]. To achieve bidirectional dynamic coupling between the particle (microscale) and continuum (macroscale) regions, the continuum solver provides state-based boundary conditions to the particle subdomain, while the particle solver provides flux-based boundary …

On The Accuracy Of Explicit Finite-Volume Schemes For Fluctuating Hydrodynamics, Aleksandar Donev, Eric Vanden-Eijnden, Alejandro Garcia, John B. Bell

Faculty Publications

This paper describes the development and analysis of finite-volume methods for the Landau–Lifshitz Navier–Stokes (LLNS) equations and related stochastic partial differential equations in fluid dynamics. The LLNS equations incorporate thermal fluctuations into macroscopic hydrodynamics by the addition of white noise fluxes whose magnitudes are set by a fluctuation-dissipation relation. Originally derived for equilibrium fluctuations, the LLNS equations have also been shown to be accurate for nonequilibrium systems. Previous studies of numerical methods for the LLNS equations focused primarily on measuring variances and correlations computed at equilibrium and for selected nonequilibrium flows. In this paper, we introduce a more systematic approach …

Measurement Of Thermoelectric Properties Of Amorphous Silicon Based Thin Films, Rubina Sultan

Electronic Theses and Dissertations

It is important to understand thermal transport behavior in materials for technological and fundamental physics applications. Many efforts have been made in the past for explaining thermal conduction in solids. It has been observed that thermal transport properties may change with reducing size of the sample, especially as sample size approaches the nanoscale regime. The deviation in these properties, mainly in thermal conductivity, may change the choice of the material for different applications such as thermoelectricity. Thermoelectric materials are a possible source of sustainable energy and can play an important role in the fight against the present energy crisis. Recently, …

Dihadron Fragmentation Functions In Proton-Proton Collisions At The Relativistic Heavy Ion Collider (Rhic), Muhammad Elnimr

Wayne State University Dissertations

Measurements of azimuthal correlations at the Relativistic Heavy Ion Collider (RHIC) have shown an away-side that is suppressed in Au+Au collisions compared to proton+proton/Deuteron+proton collisions. Such suppression is taken as a signature of the predicted QCD dense medium. However, the near-side of the azimuthal correlations shows little modification. The near-side of such correlations is related to the ratio of the dihadron fragmentation function to the single one. As such, dihadron fragmentation functions shall provide a better basis for the interpretation of the near-side correlations. Dihadron fragmentation functions also also provide a baseline of such measurements in heavy ion collisions.

Analysis Of Gamma Rays And Cosmic Muons With A Single Detector, A. Bachri, P. C. Grant, A. Goldschmidt

Journal of the Arkansas Academy of Science

In this paper, we report on the construction and upgrade of a 2002 Lawrence Berkeley National Laboratory (LBNL) Quanknet Cosmic Muons Detector. By adapting this model, we modify the electronics and mechanics to achieve a highly efficient gamma-ray and cosmic-ray detector. Each detector module uses a one-inch-thick scintillator, attached to a photomultiplier tube (PMT) and mounted on a solid aluminum frame. A mechanical support was designed to allow flexible positioning between the two modules. The detector uses scintillation to transform passing radiation into detectable photons that are guided toward a photocathode surface of the PMT, triggering the release of photoelectrons …

Super-Resolution Using Adaptive Wiener Filters, Russell C. Hardie

Electrical and Computer Engineering Faculty Publications

The spatial sampling rate of an imaging system is determined by the spacing of the detectors in the focal plane array (FPA). The spatial frequencies present in the image on the focal plane are band-limited by the optics. This is due to diffraction through a finite aperture. To guarantee that there will be no aliasing during image acquisiton, the Nyquist criterion dictates that the sampling rate must be greater than twice the cut-off frequency of the optics. However, optical designs involve a number of trade-offs and typical imaging systems are designed with some level of aliasing. We will refer to …

Harmonic Sputtering Theory, Zhu Lin Zhang

Wayne State University Dissertations

ABSTRACT

HARMONIC SPUTTERING THEORY

By

ZHU LIN ZHANG

February 2010

Advisor: Dr. Karur R. Padmanabhan

Major: Physics

Degree: Doctor of Philosophy

Based on the standard Botzmann equation in Classical Statistics Mechanics, we have derived a variety of Linear Transport Equations appeared in Sputtering Theory for a random, infinite multi-components medium. The pertinent relations among these Linear Transport Equations have been studied in detail. We have introduced exact classical scattering cross-sections of power potential interaction collision into these Transport Equations and solved them asymptotically by using Laplace Transformation for both isotropic term and anisotropic term. A pool of analytical asymptotic solutions …

The Energetic And Wave Function Properties Of Atomic, Molecular, And Solid State Systems : H⁻ Ion And The Li, Ne, And P Atoms, Bf3·Nh3 Molecular Complex And Methyl Derivatives, V2+, Cr+, Mn2+, Mn0 Transition Metal Impurities In Silicon, Roger H. Pink

Legacy Theses & Dissertations (2009 - 2024)

The variational Hartree-Fock-Roothaan (HF) method with correlation corrections introduced through Many Body Perturbation Theory (MBPT) and the variational Density Functional Theory (DFT) have been investigated for atomic systems to provide insights into the strengths and weaknesses of each variational approach to solving the multicenter many-electron Hamiltonian. The HF+MBPT method, having been found to be more reliable and physically relevant from the atomic investigations, is used to investigate the electronic structures and associated properties of the BF3*NH3 molecular complex, and through cluster methods, the most likely locations of the transitional metal impurities V2+, Cr+, Mn2+ and Mn0 in Silicon.

First Principles Investigation Of Electronic Structures And Associated Energy And Wave-Function Dependent Properties Of Biological Systems : Deoxyribonucleic Acid (Dna), Oxy-Haemoglobin, Shyam Raj Badu

Legacy Theses & Dissertations (2009 - 2024)

The Hartree-Fock procedure combined with many body perturbation theory has been used to investigate the electronic structures and associated properties of DNA systems and their corresponding muonium (Mu) adducts, as well as oxyhaemoglobin (HbO2).

Innovative Acoustic Reflection Imaging Techniques And Application To Clinical Breast Tomography, Steve Phillip Schmidt

Wayne State University Dissertations

Conventional ultrasound techniques use beam-formed, constant sound speed ray models for fast image reconstruction. However, these techniques are inadequate for the emerging new field of ultrasound tomography (UST). We present a new technique for reconstruction of reflection images from UST data. We have extended the planar Kirchhoff migration method used in geophysics, and combined it with sound speed and attenuation data obtained from the transmission signals to create reflection ultrasound images that are corrected for refractive and attenuative effects.

The resulting techniques were applied to simulated numerical phantom data, physical phantom data and in-vivo breast data obtained with an experimental …

Dynamical Theory Calculations Of Spin-Echo Resolved Grazing-Incidence Scattering From A Diffraction Grating, Rana Ashkar, P. Stonaha, A. L. Washington, V. R. Shah, M. R. Fitzsimmons, B. Maranville, C. F. Majkrzak, W. T. Lee, W. L. Schaich, Roger Pynn

Nebraska Center for Materials and Nanoscience: Faculty Publications

Neutrons scattered or reflected from a diffraction grating are subject to a periodic potential analogous to the potential experienced by electrons within a crystal. Hence, the wavefunction of the neutrons can be expanded in terms of Bloch waves and a dynamical theory can be applied to interpret the scattering phenomenon. In this paper, a dynamical theory is used to calculate the results of neutron spin-echo resolved grazing-incidence scattering (SERGIS) from a silicon diffraction grating with a rectangular profile. The calculations are compared with SERGIS measurements made on the same grating at two neutron sources: a pulsed source and a continuous …

Physics Department Centennial: An Archival Record Of Events, Rajendra Gupta

Physics Faculty Publications and Presentations

The Physics Department, University of Arkansas, celebrated its centennial during the academic year 2007-08. The celebrations consisted of a series of Centennial Lectures by distinguished physicists during the year, culminating in a three-day event from April 3 to 5, 2008. Highlights of the events included Maurer Centennial Distinguished Lecture by Nobel Laureate Wolfgang Ketterle, a talk on the 100-year history of the Physics Department by Raj Gupta, Presentation of Centennial Medallions to former/emeritus physics faculty, reunion of faculty and former students, and a banquet attended by about 400 faculty, alumni, students, and guests. This book represents an archival record (mostly …

Computational Fluctuating Fluid Dynamics, Alejandro Garcia, J. B. Bell, S. Williams

Faculty Publications

This paper describes the extension of a recently developed numerical solver for the Landau-Lifshitz Navier-Stokes (LLNS) equations to binary mixtures in three dimensions. The LLNS equations incorporate thermal fluctuations into macroscopic hydrodynamics by using white-noise fluxes. These stochastic PDEs are more complicated in three dimensions due to the tensorial form of the correlations for the stochastic fluxes and in mixtures due to couplings of energy and concentration fluxes (e.g., Soret effect). We present various numerical tests of systems in and out of equilibrium, including time-dependent systems, and demonstrate good agreement with theoretical results and molecular simulation