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Development Of A Laser-Spark Multicharged Ion System – Application In Shallow Implantation Of Sic By Boron And Barium, Md. Haider Ali Shaim

Electrical & Computer Engineering Theses & Dissertations

A novel multicharged ion source, using laser ablation induced plasma coupled with spark discharge, has been investigated in this work. The designed and demonstrated ion source is cost-effective, compact and versatile. Experiments are described with the intention of demonstrating the practicability of ion implantation via laser ion source.

Multicharged aluminum ions are generated by a ns Q-switched Nd:YAG laser pulse ablation of an aluminum target in an ultrahigh vacuum. The experiments are conducted using laser pulse energies of 45–90 mJ focused on the Al target surface by a lens with an 80-cm focal length to 0.0024 cm² spot area …

Analysis Of A Custom Support Vector Machine For Photometric Redshift Estimation And The Inclusion Of Galaxy Shape Information, Evan Jones, J. Singal

Honors Theses

Aims. We present a custom support vector machine classification package for photometric redshift estimation, including comparisons with other methods. We also explore the efficacy of including galaxy shape information in redshift estimation. Support vector machines, a type of machine learning, utilize optimization theory and supervised learning algorithms to construct predictive models based on the information content of data in a way that can treat different input features symmetrically, which can be a useful estimator of the information contained in additional features beyond photometry, such as those describing the morphology of galaxies.

Methods. The custom support vector machine package we have …

Optical Investigation Of A Hybrid System Of Plasmonic Structures And Semiconductor Quantum Dots, Matthew B. Seaton

Theses and Dissertations

Next generation integrated nanophotonic devices must fabricate large numbers of nanoscaled light coupling structures onto a single wafer: emitters such as quantum dots, resonators such as nanocavities and plasmonic nanoparticles, photonic crystal and nano-plasmonic waveguides, among others. Before precision planning and engi- neering will be possible a thorough understanding of the interaction between these structures must be documented. We present in this work an investigation of the interaction between quantum dots and plasmonic structures in the weak coupling regime. We found that surface plasmon supporting silver structures placed about 100nm from InGaAs quantum dots enabled an all optical polarization dependent …

Regulation Of Cytoplasmic Dynein By Lis1 And Adenomatous Polyposis Coli, Timothy Joshua Hines

Theses and Dissertations

Cytoplasmic dynein 1 (dynein) is a microtubule motor that plays a role in mitosis, cell migration, and minus-end directed microtubule-based transport. The lissencephaly protein, Lis1, and its binding partner, Ndel1, are critical regulators of cytoplasmic dynein (Niethammer et al., 2000). In humans, haploinsufficiency of Lis1 leads to lissencephaly, a devastating developmental neurological disorder characterized by severe brain malformation, leading to cognitive and motor defects, and progressively worsening seizures (Dobyns et al., 1993). While Lis1 is known to play a role in regulating dynein-dependent functions such as neuronal migration and mitotic spindle orientation during development, the protein is still highly expressed …

Depairing Current Density In Nbtin Superconducting Films, Nahid Shayesteh Swails

Theses and Dissertations

In this work, we systematically investigate the superconducting properties of Niobium Titanium Nitride (NbTiN) superconducting films with different geometries, which at low temperature remain superconducting. NbT iN superconducting films with a few nm thickness are widely used in devices such as superconductor-insulatorsuperconductor (SIS) mixers, superconducting cavities and resonators and superconducting nanowire single-photon detectors (SNSPD). In all these applications, films of varying dimensions are required to achieve optimal performance. The initial thickness of our samples was 125 nm deposited on a silicon substrate. We change the thickness of our samples using lithography and ion milling. We measure and analyze the thickness …

Molecular Dynamics Study Of Hydrogen Trapping And Helium Clustering In Tungsten, Ashok Gurung

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The field of plasma confinement and path toward achieving thermonuclear fusion started with experimental devices like tokamak and has evolved into other more complex variants of magnetic plasma confinement such as stellarator and spherical-tokamaks. As the plasma confinement machines advance towards higher temperature and plasma density (thermonuclear fusion conditions) the role and nature of plasma-wall interaction such as possible edge plasma regimes, particle recycling at the walls and its consequence for erosion, migration and re-deposition of wall material and impurity generation, transport and radiation as well as issues of particle exhaust continues to be a dominant limiting factor due to …

Crab Cavity Requirements For The Jefferson Lab Electron-Ion Collider, Salvador Isaac Sosa Güitrón

Physics Theses & Dissertations

An Electron-Ion Collider (EIC) has been proposed to be the next large facility to explore the dynamics of quarks and gluons inside nuclei. A conceptual design for a Jefferson Lab Electron-Ion Collider (JLEIC) is being developed. It is based on the CEBAF 12 GeV machine as a full energy electron beam injector. Two crucial requirements of JLEIC are high luminosity in the 10³⁴ cm^-2s^-1 range, and full acceptance detection of particles. The full acceptance requirement relies on having the beams collide at a relatively large crossing angle of 50 mrad. Such a large crossing angle, however, …

Development Of A 300 Kv Dc High Voltage Photogun And Beam Based Studies Of Alkali Antimonide Photocathodes, Yan Wang

Physics Theses & Dissertations

To advance magnetized gun research in the United States, a compact DC high voltage photogun with inverted-insulator geometry was designed, built, and operated reliably at - 300 kV bias voltage using alkali-antimonide photocathodes. This photogun will provide a magnetized electron beam for the future Jefferson Lab Electron-Ion Collider (JLEIC) cooler. This research describes key electrostatic design features of the photogun and evaluates the performance of the in-house fabricated photocathodes and the quality of the electron beams. The thermal emittance of the electron beam was measured with various conditions: different gun bias voltages, different laser spot sizes, and photocathodes with different …

Establishing A Quality Assurance Routine For Digital Imaging, Sulaiman Rana Al

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In the clinical medical physics field, Quality Assurance (QA) is a fundamental topic to insure patient safety and effective treatment. In recent years, the imaging hardware for diagnostic x-rays has been shifting to fully digital detectors. However, the quality assurance tests for such detectors in the clinical setting is still under development. In the Medical Imaging Department of Kettering Hospital (Kettering, OH), the currently accepted method of performing QA on detectors is to use an extensive set of tests suggested by the manufacturer. This set of tests requires about 90 minutes, which is too long for daily use. The goal …

Determination Of Dose Effects When Including Attenuation Of The Treatment Table Into Treatment Planning Computer Modeling, Abdullah Alshamrany

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During radiation treatment, the patient commonly lies on a horizontal treatment table called a couch. The material used for the couch is chosen during the manufacturing process so as to minimize the effect of the couch on dose delivery, but it still has an effect. In addition to couch attenuation on the beam, the modern approach of using multiple beam angles for dose delivery makes treatment planning in the presence of the couch more challenging. However, the effect of the couch is not always considered when creating treatment plans, generally due to treatment planning software limitations. In this evaluation, the …

Electromagnetic Properties Of Fractal Antennas, Jordan Jeffrey Ewing

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Finite element method analysis is used to conduct electromagnetic simulations to characterize fractal antennas. This work considers wire (1D) antennas such as the triadic Koch curve, zig zag, and quadratic Koch curve of varying heights, iterations, and cross-sectional areas. Carpet (2D) antennas, including the Sierpinksi carpet, of varying heights, iterations, and deterministic and stochastic iterations are analyzed. The antenna shapes were generated in MATLAB and then modeled with finite element analysis using COMSOL Multiphysics®. The focus of this study is to determine what role various fractal patterns and iterations have on the S11 return loss and far field radiation patterns. …

A Parallel Spectral Method Approach To Model Plasma Instabilities, Kevin S. Scheiman

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The study of solar-terrestrial plasma is concerned with processes in magnetospheric, ionospheric, and cosmic-ray physics involving different particle species and even particles of different energy within a single species. Instabilities in space plasmas and the earth's atmosphere are driven by a multitude of free energy sources such as velocity shear, gravity, temperature anisotropy, electron, and, ion beams and currents. Microinstabilities such as Rayleigh-Taylor and Kelvin-Helmholtz instabilities are important for the understanding of plasma dynamics in presence of magnetic field and velocity shear. Modeling these turbulences is a computationally demanding processes; requiring large memory and suffer from excessively long runtimes. Previous …