Investigation Of Gate Leakage Current In Nitrogen-Irradiated Algan/Gan Heterostructures,
2011
Air Force Institute of Technology
Investigation Of Gate Leakage Current In Nitrogen-Irradiated Algan/Gan Heterostructures, Rose E. May
Theses and Dissertations
Due to commercial and government interest in devices capable of functioning in high-power, high-frequency space applications, radiation tolerant AlGaN/GaN devices have been under study in recent years. Passivation of the AlGaN surface by (Si3N4) prevents electron trapping and enhances the 2DEG, but it also increases gate leakage currents, which can lead to device failure. This study sought information about current leakage mechanisms by introducing displacement damage close to the Si3N4/AlGaN interface. The effects of irradiation damage around the Si3N4/AlGaN interface on irradiation-induced leakage current were investigated for three …
A Comparison In The Accuracy Of Mapping Nuclear Fallout Patterns Using Hpac, Hysplit, Delfic Fpt And An Afit Fortran95 Fallout Deposition Code,
2011
Air Force Institute of Technology
A Comparison In The Accuracy Of Mapping Nuclear Fallout Patterns Using Hpac, Hysplit, Delfic Fpt And An Afit Fortran95 Fallout Deposition Code, April D. Miller
Theses and Dissertations
Four nuclear fallout mapping tools are studied to determine which tool predicts the most accurate fallout dose-rate contours with low computation time and resources. The four programs consist of the FORTRAN95 based Fallout Deposition Code (FDC), the Hazard Prediction and Assessment Capability's (HPAC) Nuclear Weapon (NWPN), the Defense Land Fallout Interpretative Code (DELFIC) Fallout Planning Tool (FPT) and the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) Model. The models were compared to the Defense Nuclear Agency's (DNA) DNA 1251-1-EX, Compilation of Local Fallout Data from Test Detonations 1945-1962 Extracted from DASA 1251, using Warner and Platt's Measure of Effectiveness (MOE) method. …
Combating Biological Terrorism From Imported Food,
2011
Air Force Institute of Technology
Combating Biological Terrorism From Imported Food, Jeffrey S. Nelson
Theses and Dissertations
There is a threat that a terrorist or terrorist organization will use access to the US food supply to kill or sicken Americans by contaminating imported food products from Mexico. The food that Americans eat is coming more and more often from foreign countries such as Mexico. Foodborne diseases infect nearly fifty million people in the US each year, resulting in over three thousand deaths. There are many terrorist organizations that would like to deliberately contaminate American food. Drug cartels and terrorist organizations currently operate in Mexico, one of the leading food importers into the US. The purpose of this …
Nuclear Weapon Yield Determination Through Nano Indentation Of Thermally Degraded Automobile Paint,
2011
Air Force Institute of Technology
Nuclear Weapon Yield Determination Through Nano Indentation Of Thermally Degraded Automobile Paint, Michael J. Richards
Theses and Dissertations
This work investigated the suitability of automotive clearcoat as a nuclear weapon yield sensor, using the change in elastic modulus as the primary metric. The AFIT Xenon Thermal Simulator (AXTS) was used to simulate a nuclear thermal pulse. The elastic modulus of the clearcoat was measured using a nano indenter. During this research the power density of the AXTS beam was increased from 44.7 to 63.7 W/cm2. The morphological steps through which automobile paint proceeds as it thermally degrades were identified and correlated with temperatures. A computer model was created and used to ensure that the paint’s time-temperature …
Analysis Of Plasma Bubble Signatures In The Ionosphere,
2011
Air Force Institute of Technology
Analysis Of Plasma Bubble Signatures In The Ionosphere, Omar A. Nava
Theses and Dissertations
Plasma bubbles are large scale structures of depleted plasma density in Earth's ionosphere that disrupt radio and satellite communications, to include global navigation satellite systems. This study used the Ionospheric Forecast Model (IFM) to analyze affected look angles and total electron content (TEC) differences due to plasma bubbles of various sizes for 27 geophysical conditions consisting of different seasons and levels of solar and geomagnetic activity at 421 GPS ground stations worldwide. Overall, different geographic locations and plasma bubble configurations produced different affected look angle profiles. Bigger plasma bubbles, larger density depletion factors, higher levels of solar activity and the …
Integration Of A Worldwide Atmospheric Based Model With A Live Virtual Constructive Simulation Environment,
2011
Air Force Institute of Technology
Integration Of A Worldwide Atmospheric Based Model With A Live Virtual Constructive Simulation Environment, David B. Simmons
Theses and Dissertations
Yearly DoD spends millions of dollars on Modeling and Simulation tools in order to accomplish two fundamental tasks: make better decisions and develop better skills. Simulators that are based on realistic models enable the USAF to properly train, educate, and employ military forces. LEEDR is an atmospheric model based on worldwide historic weather data that is able to predict the extinction, absorption, and scattering of radiation across a broad range of the electromagnetic spectrum. Through this study LEEDR models the propagation of 1.0642 micron laser radiation at worldwide locations and through various environmental conditions. This modeled laser transmission output, based …
Cathodoluminescence Of Irradiated Hafnium Dioxide,
2011
Air Force Institute of Technology
Cathodoluminescence Of Irradiated Hafnium Dioxide, Emily A. Purcell
Theses and Dissertations
The purpose of this research is to understand the effect of radiation on HfO2 thin films, and to compare the quality of HfO2 thin films produced by both atomic layer deposition (ALD) and pulsed laser deposition (PLD); PLD samples had varying substrate temperatures during deposition (300°C, 500°C, and 750°C). The entirety of this research was conducted using cathodoluminescence (CL) as the examination method. The excitation source was a Kimball Physics EMG-12 electron gun. The photomultiplier tube contained a gallium arsenide photocathode. Measurements were made with beam energies ranging from 1 to 10 keV and beam currents ranging from …
Positron Annihilation Ratio Spectroscopy Study Of Electric Fields Applied To Positronium At Material Interfaces,
2011
Air Force Institute of Technology
Positron Annihilation Ratio Spectroscopy Study Of Electric Fields Applied To Positronium At Material Interfaces, Ariella C. Walker
Theses and Dissertations
The purpose of this research was to develop a new code to analyze the data from AFIT's positron annihilation of radiation spectrometer, PsARS, system. The PsARS was used to analyze positronium formation at the surface of a capillary tube coated with gold. Using energy and geometry filters, the PsARS code determined the ratio of ortho-positronium to para-positronium. An electric field applied across the capillary tube wall forced positrons to move towards the gold surface of the capillary tube and prevent them from dropping into the Ore gap before they reach the surface. Inside the Ore gap, the positrons are more …
Passive Ranging Of Dynamic Rocket Plumes Using Infrared And Visible Oxygen Attenuation,
2011
Air Force Institute of Technology
Passive Ranging Of Dynamic Rocket Plumes Using Infrared And Visible Oxygen Attenuation, Robert Anthony Vincent
Theses and Dissertations
Atmospheric oxygen absorption bands in observed spectra of boost phase missiles can be used to accurately estimate range from sensor to target. This work compares two oxygen absorption bands in the near-infrared (NIR) and visible (Vis) spectrum, centered at 762nm and 690 nm, to passively determine range. Spectra were observed from static tests of both surface-to-air missile simulators at 405m range and a full-scale solid rocket motor at 900m range. The NIR O2 band provided range estimates accurate to within 3% for both tests, while the Vis O2 band had range errors of 77% and 15 %, respectively. …
An Analytical Model Of Nanometer Scale Viscoelastic Properties Of Polymer Surfaces Measured Using An Atomic Force Microscope,
2011
Air Force Institute of Technology
An Analytical Model Of Nanometer Scale Viscoelastic Properties Of Polymer Surfaces Measured Using An Atomic Force Microscope, Jacob B. Goldberg
Theses and Dissertations
The United States Air Force and the Department of Defense is increasingly interested in nanomaterials. To study these materials, one needs to measure the mechanics of materials on the nanoscale. Over the past few decades the atomic force microscope (AFM) has been used in various methods to establish local surface properties at the nanoscale. In particular, surface elasticity measurements are crucial to understanding nanoscale surface properties. Problems arise, however, when measuring soft surfaces such as polymers and biological specimens, because these materials have a more complex viscoelastic response. This research focuses on modeling an AFM dynamic nanoindentation experiment intended to …
Phonons Of Single Quintuple Bi2te3 And Bi2se3 Films And Bulk Materials,
2011
Illinois State University
Phonons Of Single Quintuple Bi2te3 And Bi2se3 Films And Bulk Materials, Wei Cheng, Shang-Fen Ren
Faculty publications – Physics
Phonons of single quintuple films of Bi2Te3 and Bi2Se3 and corresponding bulk materials are calculated in detail by MedeA (a trademark of Materials Design) and Vienna ab initio simulation package (VASP). The calculated results with and without spin-orbit couplings are compared, and the important roles that the spin-orbit coupling plays in these materials are discussed. A symmetry breaking caused by the anharmonic potentials around Bi atoms in the single quintuple films is identified and discussed. The observed Raman intensity features in Bi2Te3 and Bi2Se3 quintuple films are explained.
First Observation Of Bs -> D_{S2}^{*+} X Mu Nu Decays,
2011
Syracuse University
First Observation Of Bs -> D_{S2}^{*+} X Mu Nu Decays, Raymond Mountain, Marina Artuso, S. Blusk, Alessandra Borgia
Physics - All Scholarship
Using data collected with the LHCb detector in proton-proton collisions at a centre-of-mass energy of 7 TeV, the semileptonic decays Bs -> Ds+ X mu nu and Bs -> D0 K+ X mu nu are detected. Two structures are observed in the D0 K+ mass spectrum at masses consistent with the known D^+_{s1}(2536) and D^{*+}_{s2}(2573) mesons. The measured branching fractions relative to the total Bs semileptonic rate are B(Bs -> D_{s2}^{*+} X mu nu)/B(Bs -> X mu nu)= (3.3\pm 1.0\pm 0.4)%, and B(Bs -> D_{s1}^+ X munu)/B(Bs -> X mu nu)= (5.4\pm 1.2\pm 0.5)%, where the first uncertainty is statistical …
Coherent-State Transfer Via Highly Mixed Quantum Spin Chains,
2011
Massachusetts Institute of Technology
Coherent-State Transfer Via Highly Mixed Quantum Spin Chains, Paola Cappellaro, Lorenza Viola, Chandrasekhar Ramanathan
Dartmouth Scholarship
Spin chains have been proposed as quantum wires in many quantum-information processing architectures. Coherent transmission of quantum information in spin chains over short distances is enabled by their internal dynamics, which drives the transport of single-spin excitations in perfectly polarized chains. Given the practical challenge of preparing the chain in a pure state, we propose to use a chain that is initially in the maximally mixed state. We compare the transport properties of pure and mixed-state chains and find similarities that enable the experimental study of pure-state transfer via mixed-state chains. We also demonstrate protocols for the perfect transfer of …
Ar39 Detection At The 10-16 Isotopic Abundance Level With Atom Trap Trace Analysis,
2011
Argonne National Laboratory
Ar39 Detection At The 10-16 Isotopic Abundance Level With Atom Trap Trace Analysis, W. Jiang, William Williams, K. Bailey, A. M. Davis, S. M. Hu, Z. T. Lu, T. P. O'Connor, R. Purtschert, N. C. Sturchio, Y. R. Sun, P. Mueller
Physics: Faculty Publications
Atom trap trace analysis, a laser-based atom counting method, has been applied to analyze atmospheric Ar39 (half-life=269yr), a cosmogenic isotope with an isotopic abundance of 8×10-16. In addition to the superior selectivity demonstrated in this work, the counting rate and efficiency of atom trap trace analysis have been improved by 2 orders of magnitude over prior results. The significant applications of this new analytical capability lie in radioisotope dating of ice and water samples and in the development of dark matter detectors. © 2011 American Physical Society.
Time-Series Observations Of The High Mass X-Ray Binary 4u 2206+54 To Monitor Light Variation,
2011
Brigham Young University - Provo
Time-Series Observations Of The High Mass X-Ray Binary 4u 2206+54 To Monitor Light Variation, Jessica Lynn Bugno
Theses and Dissertations
The high mass X-ray binary 4U 2206+54 has been a very controversial system due to variability in spectral data as well as photometric data. We, at Brigham Young University, have been observing this system in multiple filters with several telescopes. This thesis presents our methods of observations, reductions, and results. It also compares what we have been detecting to other groups looking at the same target in different wavelengths. Furthermore, this thesis discusses some of the peculiarities of 4U 2206+54 and possible theories to explain these phenomena. Based on our photometric observations for the past three years, we believe the …
Perturbative Renormalization Of Lattice N=4 Super Yang-Mills Theory,
2011
Syracuse University
Perturbative Renormalization Of Lattice N=4 Super Yang-Mills Theory, Simon Catterall, Eric Dzienkowski, Joel Giedt, Anosh Joseph, Robert Wells
Physics - All Scholarship
We consider N=4 super Yang-Mills theory on a four-dimensional lattice. The lattice formulation under consideration retains one exact supersymmetry at non-zero lattice spacing. We show that this feature combined with gauge invariance and the large point group symmetry of the lattice theory ensures that the only counterterms that appear at any order in perturbation theory correspond to renormalizations of existing terms in the bare lattice action. In particular we find that no mass terms are generated at any finite order of perturbation theory. We calculate these renormalizations by examining the fermion and auxiliary boson self energies at one loop and …
Structures And Photoelectron Spectroscopy Of Cun(Bo2)M− (N, M = 1, 2) Clusters: Observation Of Hyperhalogen Behavior,
2011
State Key Laboratory of Molecular Reaction Dynamics, Chinese Academy of Sciences
Structures And Photoelectron Spectroscopy Of Cun(Bo2)M− (N, M = 1, 2) Clusters: Observation Of Hyperhalogen Behavior, Yuan Feng, Hong-Guang Xu, Weijun Zheng, Hongmin Zhao, Anil K. Kandalam, Puru Jena
Physics & Engineering Faculty Publications
No abstract provided.
Measurement Of The Energy Dependence Of The Total Photon-Proton Cross Section At Hera,
2011
Tel Aviv University
Measurement Of The Energy Dependence Of The Total Photon-Proton Cross Section At Hera, H. Abramowicz, I. Abt, L. Adamczyk, M. Adamus, R. Aggarwal, S. Antonelli, P. Antonioli, A. Antonov, M. Arneodo, V. Aushev, Y. Aushev, O. Bachynska, A. Bamberger, A. N. Barakbaev, G. Barbagli, G. Bari, F. Barreiro, D. Bartsch, M. Basile, O. Behnke, J. Behr, U. Behrens, L. Bellagamba, A. Bertolin, S. Bhadra, M. Bindi, C. Blohm, V. Bokhonov, T. Bold, E. G. Boos, K. Borras, Margarita C. K. Mattingly
Faculty Publications
The energy dependence of the photon-proton total cross section, σtotγp, was determined from e+p scattering data collected with the ZEUS detector at HERA at three values of the center-of-mass energy, W, of the γp system in the range 194
Pushing The Boundaries In Gradient And Shim Design For Mri,
2011
The University of Western Ontario
Pushing The Boundaries In Gradient And Shim Design For Mri, Parisa Hudson
Electronic Thesis and Dissertation Repository
High performance gradient and shim coils are highly interested for high-field magnetic resonance imaging and spectroscopy to correct for large B0 inhomogeneities created by the magnetic susceptibility differences between tissues, bone, and air. In chapter two, complete sets of high-performance gradient and shim coils are designed using two different methods: the minimum inductance and the minimum power target field methods. A quantitative comparison of shim performance in terms of merit of inductance, ML, and merit of resistance, MR, is made for shim coils designed using the minimum inductance and the minimum power design algorithms. The coils designed …
Coherent Photoproduction Of Π+ From 3he,
2011
University of Richmond
Coherent Photoproduction Of Π+ From 3he, R. Nasseripour, Gerard P. Gilfoyle, Et. Al.
Physics Faculty Publications
We have measured the differential cross section for the γ3He→ π+t reaction. This reaction was studied using the Continuous Electron Beam Accelerator Facility (CEBAF) Large Acceptance Spectrometer (CLAS) at Jefferson Lab. Real photons produced with the Hall-B bremsstrahlung tagging system in the energy range from 0.50 to 1.55 GeV were incident on a cryogenic liquid 3He target. The differential cross sections for the γ3He→ π+t reaction were measured as a function of photon-beam energy and pion-scattering angle. Theoretical predictions to date cannot explain the large cross sections except at backward angles, …
