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Noise Considerations in Nuclear Pulse Amplifiers

Description: The effects of certain pulse-shaping networks on the signal-to-noise ratio of a nuclear pulse amplifier were considered. The shaping networks discussed are: equal RC-integrating and RC-differentiating time constant, single- delay-line clipper and RC integrator, and doubledelay-line clipper and RC integrator. The effects of these networks on the signal, when high count rates and overload pulses are present, were also considered. Equations and curves were developed for the energy resolution (sign… more
Date: December 20, 1961
Creator: Landis, D. A.
Partner: UNT Libraries Government Documents Department
open access

Production, Characterization, and Acceleration of Optical Microbunches

Description: Optical microbunches with a spacing of 800 nm have been produced for laser acceleration research. The microbunches are produced using a inverse Free-Electron-Laser (IFEL) followed by a dispersive chicane. The microbunched electron beam is characterized by coherent optical transition radiation (COTR) with good agreement to the analytic theory for bunch formation. In a second experiment the bunches are accelerated in a second stage to achieve for the first time direct net acceleration of electron… more
Date: June 20, 2008
Creator: Sears, Christopher M.S. & /SLAC, /Stanford U.
Partner: UNT Libraries Government Documents Department
open access

Nanolithographic Fabrication and Heterogeneous Reaction Studies ofTwo-Dimensional Platinum Model Catalyst Systems

Description: In order to better understand the fundamental components that govern catalytic activity, two-dimensional model platinum nanocatalyst arrays have been designed and fabricated. These catalysts arrays are meant to model the interplay of the metal and support important to industrial heterogeneous catalytic reactions. Photolithography and sub-lithographic techniques such as electron beam lithography, size reduction lithography and nanoimprint lithography have been employed to create these platinum n… more
Date: May 20, 2006
Creator: Contreras, A.M.
Partner: UNT Libraries Government Documents Department
open access

Superconducting submillimeter and millimeter wave detectors

Description: The series of projects described in this dissertation was stimulated by the discovery of high temperature superconductivity. Our goal was to develop useful applications which would be competitive with the current state of technology. The high-{Tc} microbolometer was developed into the most sensitive direct detector of millimeter waves, when operated at liquid nitrogen temperatures. The thermal boundary resistance of thin YBa{sub 2}Cu{sub 3}0{sub 7-{delta}} films was subsequently measured and pr… more
Date: October 20, 1992
Creator: Nahum, M.
Partner: UNT Libraries Government Documents Department
open access

BioAerosol Mass Spectrometry: Reagentless Detection of Individual Airborne Spores and Other Bioagent Particles Based on Laser Desorption/Ionization Mass Spectrometry

Description: Better devices are needed for the detection of aerosolized biological warfare agents. Advances in the ongoing development of one such device, the BioAerosol Mass Spectrometry (BAMS) system, are described here in detail. The system samples individual, micrometer-sized particles directly from the air and analyzes them in real-time without sample preparation or use of reagents. At the core of the BAMS system is a dual-polarity, single-particle mass spectrometer with a laser based desorption and io… more
Date: July 20, 2004
Creator: Steele, P T
Partner: UNT Libraries Government Documents Department
open access

Determination of the Azimuthal Asymmetry of Deuteron Photodisintegration in the Energy Region E{sub {gamma}} = 1.1 - 2.3 GeV

Description: Deuteron photodisintegration is a benchmark process for the investigation of the role of quarks and gluons in nuclei. Existing theoretical models of this process describe the available cross sections with the same degree of success. Therefore, spin-dependent observables are crucial for a better understanding of the underlying dynamical mechanisms. However, data on the induced polarization (P{sub y}), along with the polarization transfers (C{sub x'} and C{sub z'} ), have been shown to … more
Date: May 20, 2012
Creator: Zachariou, Nicholas
Partner: UNT Libraries Government Documents Department
open access

Unorthodox theoretical methods

Description: The use of the ReaxFF force field to correlate with NMR mobilities of amine catalytic substituents on a mesoporous silica nanosphere surface is considered. The interfacing of the ReaxFF force field within the Surface Integrated Molecular Orbital/Molecular Mechanics (SIMOMM) method, in order to replicate earlier SIMOMM published data and to compare with the ReaxFF data, is discussed. The development of a new correlation consistent Composite Approach (ccCA) is presented, which incorporates the co… more
Date: June 20, 2012
Creator: Nedd, Sean
Partner: UNT Libraries Government Documents Department
open access

Search for Lepton Flavour Violating Decays Tau -> l Ks with the BABAR Detector

Description: We present the search for the lepton flavour violating decay {tau} {yields} lK{sup 0}{sub s} with the BaBar experiment data. This process and many other lepton flavour violating {tau} decays, like {tau} {yields} {mu}{gamma} and {tau} {yields} lll, are one of the most promising channel to search for evidence of new physics. According to the Standard Model and the neutrino mixing parameters, branching fractions are estimated well below 10{sup -14}, but many models of new physics allow for branchi… more
Date: March 20, 2009
Creator: Cenci, Riccardo
Partner: UNT Libraries Government Documents Department
open access

The Development of the Electrically Controlled High Power RF Switch and Its Application to Active RF Pulse Compression Systems

Description: In the past decades, there has been increasing interest in pulsed high power RF sources for building high-gradient high-energy particle accelerators. Passive RF pulse compression systems have been used in many applications to match the available RF sources to the loads requiring higher RF power but a shorter pulse. Theoretically, an active RF pulse compression system has the advantage of higher efficiency and compactness over the passive system. However, the key component for such a system an e… more
Date: March 20, 2009
Creator: Guo, Jiquan
Partner: UNT Libraries Government Documents Department
open access

Building Structural Complexity in Semiconductor Nanocrystals through Chemical Transformations

Description: Methods are presented for synthesizing nanocrystal heterostructures comprised of two semiconductor materials epitaxially attached within individual nanostructures. The chemical transformation of cation exchange, where the cations within the lattice of an ionic nanocrystal are replaced with a different metal ion species, is used to alter the chemical composition at specific regions ofa nanocrystal. Partial cation exchange was performed in cadmium sulfide (CdS) nanorods of well-defined size and s… more
Date: May 20, 2009
Creator: Sadtler, Bryce F.
Partner: UNT Libraries Government Documents Department
open access

Extreme ultraviolet lithography: A few more pieces of the puzzle

Description: The work described in this dissertation has improved three essential components of extreme ultraviolet (EUV) lithography: exposure tools, photoresist, and metrology. Exposure tools. A field-averaging illumination stage is presented that enables nonuniform, high-coherence sources to be used in applications where highly uniform illumination is required. In an EUV implementation, it is shown that the illuminator achieves a 6.5% peak-to-valley intensity variation across the entire design field of v… more
Date: May 20, 2009
Creator: Anderson, Christopher N.
Partner: UNT Libraries Government Documents Department
open access

Developing nanotechnology for biofuel and plant science applications

Description: This dissertation presents the research on the development of mesoporous silica based nanotechnology for applications in biofuels and plant science. Mesoporous silica nanoparticles (MSNs) have been the subject of great interest in the last two decades due to their unique properties of high surface area, tunable pore size and particle morphology. The robust nature of the silica framework is easily functionalized to make the MSNs a promising option for selective separations. Also, the independent… more
Date: June 20, 2012
Creator: Valenstein, Justin
Partner: UNT Libraries Government Documents Department
open access

Masters Thesis- Criticality Alarm System Design Guide with Accompanying Alarm System Development for the Radioisotope Production Laboratory in Richland, Washington

Description: A detailed instructional manual was created to guide criticality safety engineers through the process of designing a criticality alarm system (CAS) for Department of Energy (DOE) hazard class 1 and 2 facilities. Regulatory and technical requirements were both addressed. A list of design tasks and technical subtasks are thoroughly analyzed to provide concise direction for how to complete the analysis. An example of the application of the design methodology, the Criticality Alarm System developed… more
Date: December 20, 2009
Creator: Greenfield, Bryce A.
Partner: UNT Libraries Government Documents Department
open access

Dynamical Study of Guest-Host Orientational Interaction in LiquidCrystalline Materials

Description: Guest-host interaction has long been a subject of interest in many disciplines. Emphasis is often on how a small amount of guest substance could significantly affect the properties of a host material. This thesis describe our work in studying a guest-host effect where dye-doping of liquid crystalline materials greatly enhances the optical Kerr nonlinearity of the material. The dye molecules, upon excitation and via intermolecular interaction, provides an extra torque to reorient the host molecu… more
Date: December 20, 2005
Creator: Truong, Thai Viet
Partner: UNT Libraries Government Documents Department
open access

Fast Ignition Experimental and Theoretical Studies

Description: We are becoming dependent on energy more today than we were a century ago, and with increasing world population and booming economies, sooner or later our energy sources will be exhausted. Moreover, our economy and welfare strongly depends on foreign oil and in the shadow of political uncertainties, there is an urgent need for a reliable, safe, and cheap energy source. Thermonuclear fusion, if achieved, is that source of energy which not only will satisfy our demand for today but also for centu… more
Date: October 20, 2006
Creator: Akli, K
Partner: UNT Libraries Government Documents Department
open access

Cobalt Nanocrystals as Starting Materials for Shape Modificationand Assembly Formation

Description: Surfactant-coated cobalt nanocrystals can be prepared with areasonable degree of control over particle size and shape using athermolytic route. The small crystallite size, enhanced reactivity andtunable interparticle interactions enable use of this material asstarting material for demonstration of achievement of novel structuresusing extremely simple solution-based approaches. In particular,formation of hollow cobalt sulfide nanocrystals upon chemicalmodification and emergence of long-range ori… more
Date: December 20, 2005
Creator: Erdonmez, Can Kerem
Partner: UNT Libraries Government Documents Department
open access

Biomolecular Assembly of Gold Nanocrystals

Description: Over the past ten years, methods have been developed to construct discrete nanostructures using nanocrystals and biomolecules. While these frequently consist of gold nanocrystals and DNA, semiconductor nanocrystals as well as antibodies and enzymes have also been used. One example of discrete nanostructures is dimers of gold nanocrystals linked together with complementary DNA. This type of nanostructure is also known as a nanocrystal molecule. Discrete nanostructures of this kind have a number … more
Date: May 20, 2005
Creator: Micheel, Christine Marya
Partner: UNT Libraries Government Documents Department
open access

Genotyping and Bioforensics of Ricinus communis

Description: The castor bean plant (Ricinus communis) is a member of the family Euphorbiaceae. In spite of its common name, the castor plant is not a true bean (i.e., leguminous plants belonging to the family, Fabaceae). Ricinus communis is native to tropical Africa, but because the plant was recognized for its production of oil with many desirable properties, it has been introduced and cultivated in warm temperate regions throughout the world (Armstrong 1999 and Brown 2005). Castor bean plants have also be… more
Date: November 20, 2006
Creator: Hinckley, A C
Partner: UNT Libraries Government Documents Department
open access

NUCLEAR SPECTROSCOPIC STUDIES OF SOME VERY HEAVY ODD-MASS NUCLIDES

Description: The nuclear radiations of nuclides: U{sup 233}, Pu{sup 239}, Bk{sup 243}, Bk{sup 244}, Bk{sup 245}, Bk{sup 246}, Bk{sup 249}, Cf{sup 249}, and Fm{sup 255} were investigated with high-resolution spectrometers. The {alpha}-particle spectra of all nuclides except Bk{sup 249} were measured with 6 mm diameter surface-barrier detectors. Bk{sup 249} {alpha}-particles were analyzed with a double-focusing magnetic spectrograph. The {gamma}-singles were examined with the recently developed Ge(Li) and Si(… more
Date: September 20, 1966
Creator: Ahmad, Irshad
Partner: UNT Libraries Government Documents Department
open access

Linking Automated Data Analysis and Visualization with Applications in Developmental Biology and High-Energy Physics

Description: Knowledge discovery from large and complex collections of today's scientific datasets is a challenging task. With the ability to measure and simulate more processes at increasingly finer spatial and temporal scales, the increasing number of data dimensions and data objects is presenting tremendous challenges for data analysis and effective data exploration methods and tools. Researchers are overwhelmed with data and standard tools are often insufficient to enable effective data analysis and kn… more
Date: November 20, 2009
Creator: Ruebel, Oliver
Partner: UNT Libraries Government Documents Department
open access

A search for $ZH\rightarrow \mu\mu b \bar{b}$ production at the Tevatron

Description: The Standard Model describes with a very good accuracy all interactions of the, so far, known elementary particles. However the Higgs mechanism, which gives rise to the observed mass of these particles, has not yet been confirmed. The Higgs particle has not yet been observed, and the observation or exclusion is an important test of the Standard Model. The Standard Model does not predict the mass of the Higgs particle, however it does impose some limits on the range in which this mass can lie. I… more
Date: April 20, 2010
Creator: Ancu, Lucian-Stefan
Partner: UNT Libraries Government Documents Department
open access

Recombination and propagation of quasiparticles in cuprate superconductors

Description: Rapid developments in time-resolved optical spectroscopy have led to renewed interest in the nonequilibrium state of superconductors and other highly correlated electron materials. In these experiments, the nonequilibrium state is prepared by the absorption of short (less than 100 fs) laser pulses, typically in the near-infrared, that perturb the density and energy distribution of quasiparticles. The evolution of the nonequilibrium state is probed by time resolving the changes in the optical re… more
Date: May 20, 2004
Creator: Gedik, Nuh
Partner: UNT Libraries Government Documents Department
open access

Aspects of the SrO-CuO-TiO2 Ternary System Related to the Deposition of SrTiO3 and Copper-Doped SrTiO3 Thin-Film Buffer Layers

Description: YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} (YBCO) coated conductors are promising materials for large-scale superconductivity applications. One version of a YBCO coated conductor is based on ion beam assisted deposition (IBAD) of magnesium oxide (MgO) onto polycrystalline metal substrates. SrTiO{sub 3} (STO) is often deposited by physical vapor deposition (PVD) methods as a buffer layer between the YBCO and IBAD MgO due to its chemical stability and lattice mismatch of only {approx}1.5% with YBCO. In … more
Date: December 20, 2004
Creator: Ayala, A.
Partner: UNT Libraries Government Documents Department
open access

Atomic Capture of $mu$$sup -$ Mesons in Chemical Compounds and The "Fermiteller Z Law"

Description: Experimental studies of the relative atomic mu --meson capture probabilities in the constituents of chemical compounds are described. Fermi and Teller had predicted that the atomic-capture probability is proportional to the nuclear charge of the atomic species weighted by its atomic concentration. This is sometimes referred to as the Fermi-Teller Z law.'' Previous experiments indicated no clear systematics to this capture process, and there are conflicts between the results of several measureme… more
Date: August 20, 1962
Creator: Baijal, J. S.
Partner: UNT Libraries Government Documents Department
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