2,373 Matching Results

Search Results

prev Results: 49 - 72 next
open access

The Moderation of Neutrons in Non-Multiplying Infinite Homogeneous Media.

Description: Submitted to Univ. of Minnesota, Minneapolis. The gas model of neutron thermalization for a general moderator mass was studied by formulating the thermalization process as an integral equation. The relation of the model to the slowing-down theory was investigated. A discussion of the theory of scattering cross sections for neutrons is presented. The Wigner-Wilkins model was considered for moderator atoms of the same mass as the neutron. The analysis was extended to the case of a gaseous moderat… more
Date: January 1, 1962
Creator: Min, K.
Partner: UNT Libraries Government Documents Department
open access

Heated uranium tetrafluoride target system to release non-rare gas fission products for the TRISTAN isotope separator. [As replacement for uranyl stearate]

Description: Off-line experiments indicated that fluorides of As, Se, Br, Kr, Zr, Nb, Mo, Tc, Ru, Sb, Te, I and Xe could be volatilized, but except for Br, Kr, I and Xe, none of these elements were observed after mass separation in the on-line experiments. The results of the on-line experiments indicated a very low level of hydride contamination at ambient temperature and consequently, uranium tetrafluoride replaced uranyl stearate as the primary gaseous fission product target. Possible reasons for the fail… more
Date: October 1, 1977
Creator: Gill, R. L.
Partner: UNT Libraries Government Documents Department
open access

Thermodynamics of solid and liquid group III-V alloys

Description: Solid-state electrochemical techniques are applied to the Ga-In-Sb-O system to measure some thermodynamic properties important for the analysis of solid-liquid phase equilibria in these important semiconductor materials. The standard Gibbs energies of formation of the most stable oxides of gallium and of indium are determined with a high-temperature solid-state electrochemical cell utilizing calcia-stabilized zirconia as the solid electrolyte and a (CO + CO/sub 2/) gaseous mixture as the refere… more
Date: October 1, 1978
Creator: Anderson, T. J.
Partner: UNT Libraries Government Documents Department
open access

Interpretation of time domain electromagnetic soundings near geological contacts

Description: Lateral changes in geology pose a serious problem in data interpretation for any surface geophysical method. Although many geophysical techniques are designed to probe vertically, the source signal invariably spreads laterally, so any lateral variations in geology will affect the measurements and interpretation. This problem is particularly acute for controlled source electromagnetic soundings because only a few techniques are available to interpret the data if lateral effects are present. In t… more
Date: December 1, 1991
Creator: Wilt, Michael Joseph
Partner: UNT Libraries Government Documents Department
open access

Investigation of the validity of the OZI rule and study of production properties of the anti K*/sup. / resonance in. pi. /sup +/p interactions at 16 GeV/c

Description: Results are reported from a streamer chamber experiment performed at Stanford Linear Accelerator Center (SLAC) to study the production of the phi (1020) in OZI-allowed and forbidden processes in ..pi../sup +/p interactions at 16 GeV/c. Production properties of the anti K*/sup ./(896) are also studied and discussed.
Date: September 1, 1981
Creator: Jawahery, A.
Partner: UNT Libraries Government Documents Department
open access

Evaluation of self-interaction parameters from binary phase diagrams

Description: The feasibility of calculating Wagner self-interaction parameters from binary phase diagrams was examined. The self-interaction parameters of 22 non-ferrous liquid solutions were calculated utilizing an equation based on the equality of the chemical potentials of a component in two equilibrium phases. Utilization of the equation requires the evaluation of the first and second derivatives of various liquidus and solidus data at infinite dilution of the solute component. Several numerical methods… more
Date: October 1, 1977
Creator: Ellison, T. L.
Partner: UNT Libraries Government Documents Department
open access

Multiconfigurational electronic wavefunctions in the full optimized reaction space: the isomerization of nitrosyl hydride to nitrogen hydroxide in the lowest singlet and triplet states

Description: Energy curves are determined for the lowest singlet and triplet states of the HNO molecule. The geometry is varied in that the hydrogen moves through 13 positions around the NO core to describe the isomerization reaction HNO yields HON. Quantitatively determined are the stable and metastable equilibrium positions in both states, the energy differences between these two equilibrium positions and between the two states, and the barriers with respect to isomerization. The calculations are carried … more
Date: December 1, 1977
Creator: Dombek, M. G.
Partner: UNT Libraries Government Documents Department
open access

Vaporization of synthetic fuels. Final report.

Description: The problem of transient droplet vaporization in a hot convective environment is examined. The main objective of the present study is to develop an algorithm for the droplet vaporization which is simple enough to be feasibly incorporated into a complete spray combustion analysis and yet will also account for the important physics such as liquid-phase internal circulation, unsteady droplet heating and axisymmetric gas-phase convection. A simplified liquid-phase model has been obtained based on t… more
Date: January 1, 1983
Creator: Sirignano, W. A.; Yao, S. C.; Tong, A. Y. & Talley, D.
Partner: UNT Libraries Government Documents Department
open access

Electronic transitions of some pi-molecular charge transfer complexes. [Anthracene--pyromellitic dianhydride (PMDA) or pyrene--PMDA in naphthalene--PMDA host]

Description: A unique phonon progression in the phosphorescence spectrum of pyrene-PMDA (Py-PMDA) in naphthalene-PMDA (N-PMDA) is reported. Calculations of the electron-phonon coupling strength parameter for the ground and excited states indicate strong coupling for the fractional CT contribution of Py-PMDA to the observed phosphorescent state. Model calculations indicate that the observed low frequency phonon mode corresponds to a low energy rotation of the rigid guest complex and not a symmetric donor-acc… more
Date: December 1, 1977
Creator: Beckman, R. L.
Partner: UNT Libraries Government Documents Department
open access

Mass-spectrometric determination of trace elements in aqueous media without preconcentration

Description: Feasibility of using a low pressure glow discharge as an ion source for the mass spectrometric determination of trace elements in aqueous media was investigated. A cryogenically cooled hollow cathode ion source was developed to analyze aqueous samples without external preconcentration. Aqueous solutions containing seventy elements were analyzed and the detection limits, sensitivity factors, and linear regression correlation coefficients were determined. A standard test solution of trace element… more
Date: October 1, 1981
Creator: Foss, G. O.
Partner: UNT Libraries Government Documents Department
open access

A search for sterile neutrinos in MINOS

Description: MINOS, the Main Injector Neutrino Oscillation Search, is a long baseline neutrino oscillation experiment based at Fermilab National Accelerator Laboratory. The experiment uses a neutrino beam, which is measured 1 km downstream from its origin in the Near detector at Fermilab and then 735 km later in the Far detector at the Soudan mine. By comparing these two measurements, MINOS can attain a very high precision for parameters in the atmospheric sector of neutrino oscillations. In addition to pre… more
Date: December 1, 2007
Creator: Osiecki, Thomas Henry
Partner: UNT Libraries Government Documents Department
open access

CARBON-13 NMR STUDIES OF LIQUID CRYSTALS

Description: High resolution, proton decoupled {sup 13}C nmr are observed for a series of neat nematic liquid crystals, the p-alkoxyazoxybenzenes, and a smectic-A liquid crystal, diethylazoxydibenzoate in a magnetic field of 23 kG. The (uniaxial) order parameters S = <P{sub 2}(cos{theta})> are found to be about 0.4 and 0.9 for the nematic and smectic-A phase respectively at the clearing points. The order parameter increases with decreasing temperature in the nematic phase but is constant, or nearly so… more
Date: June 1, 1975
Creator: Allison, Stuart
Partner: UNT Libraries Government Documents Department
open access

Measurements of Direct CP Violation, CPT Symmetry, and Other Parameters in the Neutral Kaon System

Description: The authors present precision measurements of the direct CP violation parameter, Re({epsilon}{prime}/{epsilon}), the kaon parameters, {Delta}m and {tau}{sub S}, and the CPT tests, {phi}{sub {+-}} and {Delta}{phi}, in neutral kaon decays. These results are based on the full dataset collected by the KTeV experiment at Fermi National Accelerator Laboratory during 1996, 1997, and 1999. This dataset contains {approx} 15 million K {yields} {pi}{sup 0}{pi}{sup 0} decays and {approx} 69 million K {yiel… more
Date: December 1, 2007
Creator: Worcester, Elizabeth Turner
Partner: UNT Libraries Government Documents Department
open access

A measurement of the top quark's charge

Description: The top quark was discovered in 1995 at the Fermilab National Accelerator Laboratory (Fermilab). One way to confirm if the observed top quark is really the top quark posited in the Standard Model (SM) is to measure its electric charge. In the Standard Model the top quark is the isospin partner of the bottom quark and is expected to have a charge of +2/3. However, an alternative 'exotic' model has been proposed with a fourth generation exotic quark that has the same characteristics, such as mass… more
Date: November 1, 2007
Creator: Unalan, Zeynep Gunay
Partner: UNT Libraries Government Documents Department
open access

Processing and Protection of Rare Earth Permanent Magnet Particulate for Bonded Magnet Applications

Description: Rapid solidification of novel mixed rare earth-iron-boron, MRE{sub 2}Fe{sub 14}B (MRE = Nd, Y, Dy; currently), magnet alloys via high pressure gas atomization (HPGA) have produced similar properties and structures as closely related alloys produced by melt spinning (MS) at low wheel speeds. Recent additions of titanium carbide and zirconium to the permanent magnet (PM) alloy design in HPGA powder (using He atomization gas) have made it possible to achieve highly refined microstructures with mag… more
Date: December 1, 2007
Creator: Sokolowski, Peter Kelly
Partner: UNT Libraries Government Documents Department
open access

Studying neutrino oscillations using quasi-elastic events in MINOS

Description: MINOS (Main Injector Neutrino Oscillation Search), is a long baseline neutrino experiment designed to search for neutrino oscillations using two detectors at Fermi National Accelerator Laboratory, IL (Near Detector) and Soudan, MN (Far Detector). It will study {nu}{sub {mu}} {yields} {nu}{sub {tau}} oscillations and make a measurement on the oscillation parameters, {Delta}m{sub 23}{sup 2} and sin{sup 2} 2{theta}{sub 23}, via a {nu}{sub {mu}} beam made at Fermilab. Charge current neutrino intera… more
Date: February 1, 2008
Creator: Kumaratunga, Sujeewa Terasita
Partner: UNT Libraries Government Documents Department
open access

M5Si3(M=Ti, Nb, Mo) Based Transition-Metal Silicides for High Temperature Applications

Description: Transition metal silicides are being considered for future engine turbine components at temperatures up to 1600 C. Although significant improvement in high temperature strength, room temperature fracture toughness has been realized in the past decade, further improvement in oxidation resistance is needed. Oxidation mechanism of Ti{sub 5}Si{sub 3}-based alloys was investigated. Oxidation behavior of Ti{sub 5}Si{sub 3}-based alloy strongly depends on the atmosphere. Presence of Nitrogen alters th… more
Date: December 1, 2007
Creator: Tang, Zhihong
Partner: UNT Libraries Government Documents Department
open access

Measurement of the ttbar production cross section in the MET+jets channel at CDF

Description: This thesis is focused on an inclusive search of the t{bar t} {yields} E{sub T} + jets decay channel by means of neural network tools in proton antiproton collisions at {radical}s = 1.96 TeV recorded by the Collider Detector at Fermilab (CDF). At the Tevatron p{bar p} collider top quarks are mainly produced in pairs through quark-antiquark annihilation and gluon-gluon fusion processes; in the Standard Model description, the top quark then decays to a W boson and a b quark almost 100% of the tim… more
Date: March 1, 2008
Creator: Compostella, Gabriele & /INFN, Trento
Partner: UNT Libraries Government Documents Department
open access

A measurement of the top quark mass in 1.96 TeV proton-antiproton collisions using a novel matrix element method

Description: A measurement of the top quark mass in t{bar t} {yields} l + jets candidate events, obtained from p{bar p} collisions at {radical}s = 1.96 TeV at the Fermilab Tevatron using the CDF II detector, is presented. The measurement approach is that of a matrix element method. For each candidate event, a two dimensional likelihood is calculated in the top pole mass and a constant scale factor, 'JES', where JES multiplies the input particle jet momenta and is designed to account for the systematic uncer… more
Date: December 1, 2007
Creator: Freeman, John C.
Partner: UNT Libraries Government Documents Department
open access

Search for Higgs Boson Production in Association with the W boson in 1.96-TeV Proton-Antiproton Collisions

Description: A search for the Standard Model Higgs boson was carried out in WH {yields} {ell}{nu}b{bar b} process in p{bar p} collisions at a center of mass energy of 1.96 TeV, where W, H, {ell}, {nu}, b and p denote either a W{sup +} or W{sup -} boson, Higgs boson, lepton (electron or muon), neutrino, bottom quark and proton, respectively. The data were collected with the Collider Detector at Fermilab from February 2002 to August 2004. The corresponding integrated luminosity is 319 pb{sup -1}. We select ev… more
Date: September 1, 2005
Creator: Ishizawa, Yoshio
Partner: UNT Libraries Government Documents Department
open access

Observation of Disappearance of Muon Neutrinos in the NuMI Beam

Description: The Main Injector Neutrino Oscillation Search (MINOS) is a two detector long-baseline neutrino experiment designed to study the disappearance of muon neutrinos. MINOS will test the {nu}{sub {mu}} {yields} {nu}{sub {tau}} oscillation hypothesis and measure precisely {Delta}m{sub 23}{sup 2} and sin{sup 2} 2{theta}{sub 23} oscillation parameters. The source of neutrinos for MINOS experiment is Fermilab's Neutrinos at the Main Injector (NuMI) beamline. The energy spectrum and the composition of the… more
Date: May 1, 2008
Creator: Pavlovic, Zarko
Partner: UNT Libraries Government Documents Department
Back to Top of Screen