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621 Matching Results
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Optics Performance at 1(omega), 2 (omega), and 3 (omega): Final Report on LDRD Project 03-ERD-071
The interaction of intense laser light with dielectric materials is a fundamental applied science problem that is becoming increasingly important with the rapid development of ever more powerful lasers. To better understand the behavior of optical components in large fusion-class laser systems, we are systematically studying the interaction of high-fluence, high-power laser light with high-quality optical components, with particular interest on polishing/finishing and stress-induced defects and surface contamination. We focus on obtaining comparable measurements at three different wavelengths, 1{omega} (1053 nm), 2{omega} (527 nm), and 3{omega} (351 nm).
Date:
February 8, 2006
Creator:
Honig, J.; Adams, J.; Carr, C.; Demos, S.; Feit, M.; Mehta, N. et al.
Object Type:
Report
System:
The UNT Digital Library
Constraining |V(td)|/|V(ts)| Using Radiative Penguin B -> V(K*/rho/omega)gamma Decays
Exclusive radiative penguin B decays, B {yields} (K*{sup 0}/K*{sup +}) and B {yields} ({rho}/{omega}){gamma}, are flavor-changing neutral-current (FCNC) processes. Studies of these decays are of special interest in testing Standard Model (SM) predictions and searching for other beyond-the-SM FCNC interactions. Using 89 x 10{sup 6} B{bar B} pairs from BABAR, we measure the branching fraction ({Beta}), CP-asymmetry ({Alpha}), and isospin asymmetry ({Delta}{sub 0-}) of B {yields} (K*{sup 0}/K*{sup +}){gamma} as follows: {Beta}(B{sup 0} {yields} K*{sup 0}{gamma}) = 3.92 {+-} 0.20(stat.) {+-} 0.24(syst.); {Beta}(B{sup +} {yields} K*{sup +}{gamma}) = 3.87 {+-} 0.28(stat.) {+-} 0.26(syst.); {Alpha}(B {yields} K*{gamma}) = -0.013 {+-} 0.36(stat.) {+-} 0.10(syst.); {Delta}{sub 0-}(B {yields} K*{gamma}) = 0.050 {+-} 0.045(stat.) {+-} 0.028(syst.) {+-} 0.024(R{sup +/0}). The 90% confidence intervals for the CP-asymmetry and the isospin-asymmetry in the B {yields} K*{gamma} decay are given as: -0.074 < {Alpha}(B {yields} K*{gamma}) < 0.049, -0.046 < {Delta}{sub 0-} (B {yields} K*{gamma}) < 0.146. We also search for B {yields} ({rho}/{omega}){gamma} decays using 211 x 10{sup 6} B{bar B} pairs from BABAR. No evidence for these decays is found. We set the upper limits at 90% confidence level for these decays: {Beta}(B{sup 0} {yields} {rho}{sup 0}{gamma}) < 0.4 x 10{sup -6}; {Beta}(B{sup +}{yields} {rho}{sup …
Date:
March 8, 2006
Creator:
Tan, Ping
Object Type:
Report
System:
The UNT Digital Library
Measurement of the asymmetry in the decay Antiomega+ ---> Antilambda K+ ---> anti-p pi+ K+
The asymmetry in the {bar p} angular distribution in the sequential decay {bar {Omega}}{sup +} {yields} {bar {Lambda}}K{sup +} {yields} {bar p}{pi}{sup +}K{sup +} has been measured to be {bar {alpha}}{sub {Omega}}{bar {alpha}}{sub {Lambda}} = [+1.16{+-}0.18(stat){+-}0.17(syst)]x10{sup -2} using 1.89x10{sup 6} unpolarized {bar {Omega}}{sup +} decays recorded by the Hyper CP (E871) experiment at Fermilab. Using the known value of {alpha}{sub {Lambda}}, and assuming that {bar {alpha}}{sub {Lambda}} = -{alpha}{sub {Lambda}}, {bar {alpha}}{sub {Omega}} = [-1.81{+-}0.28(stat){+-}0.26(syst)]x10{sup -2}. A comparison between this measurement of {bar {alpha}}{sub {Omega}}{bar {alpha}}{sub {Lambda}} and recent measurements of {alpha}{sub {Omega}}{alpha}{sub {Lambda}} made by HyperCP shows no evidence of a violation of CP symmetry.
Date:
January 1, 2006
Creator:
Lu, L. C.; Burnstein, R. A.; Chakravorty, A.; Chen, Y. C.; Choong, W. S.; Clark, K. et al.
Object Type:
Article
System:
The UNT Digital Library
The Hexagon, Volume 97, Number 2, Summer 2006
Quarterly publication of the Alpha Chi Sigma chemistry fraternity containing articles related to chemistry research and the activities of the organization, including local chapters and groups.
Date:
Summer 2006
Creator:
Alpha Chi Sigma
Object Type:
Journal/Magazine/Newsletter
System:
The UNT Digital Library
The Hexagon, Volume 97, Number 3, Fall 2006
Quarterly publication of the Alpha Chi Sigma chemistry fraternity containing articles related to chemistry research and the activities of the organization, including local chapters and groups.
Date:
Autumn 2006
Creator:
Alpha Chi Sigma
Object Type:
Journal/Magazine/Newsletter
System:
The UNT Digital Library
An Analysis of the X-Ray Diffraction Signal for the (alpha) - (epsilon) Transition in Shock-Compressed Iron: Simulation and Experiment
Recent published work has shown that the phase change of shock compressed iron along the [001] direction does transform to the {epsilon} (HCP) phase similar to the case for static measurements. This article provides an indepth analysis of the experiment and NEMD simulations, using x-ray diffraction in both cases to study the crystal structure upon transition. Both simulation and experiment are consistent with a compression and shuffle mechanism responsible for the phase change from BCC to HCP. Also both show a polycrystalline structure upon the phase transition, due to the four degenerate directions the phase change can occur on, with grain sizes measured of 4nm in the NEMD simulations and {approx} 2nm in the experiment. And looking at the time scale of the transition the NEMD shows the transition from the compressed BCC to HCP is less then 1.2 ps where the experimental data places an upper limit on the transition of 80 ps.
Date:
April 10, 2006
Creator:
Hawreliak, J; Colvin, J D; Kalantar, D H; Lorenzana, H E; Stolken, J S; Davies, H M et al.
Object Type:
Article
System:
The UNT Digital Library
Measurements of CP-Violating Asymmetries and BranchingFractions in B Decays to omegaK and omegaPi
We present measurements of CP-violating asymmetries and branching fractions for the decays B{sup +} {yields} {omega}{pi}{sup +}, B{sup +} {yields} {omega}K{sup +}, and B{sup 0} {yields} {omega}K{sup 0}. The data sample corresponds to 232 million B{bar B} pairs produced by e{sup +}e{sup -} annihilation at the {Upsilon}(4S) resonance. For the decay B{sup 0} {yields} {omega}K{sub s}{sup 0}, we measure the time-dependent CP-violation parameters S = 0.51{sub -0.39}{sup +0.35} {+-} 0.02, and C = -0.55{sub -0.26}{sup +0.28} {+-} 0.03. We also measure the branching fractions, in units of 10{sup -6}, {Beta}(B{sup +} {yields} {omega}{pi}{sup +}) = 6.1 {+-} 0.7 {+-} 0.4, {Beta}(B{sup +} {yields} {omega}K{sup +}) = 6.1 {+-} 0.6 {+-} 0.4, and {Beta}(B{sup 0} {yields} {omega}K{sup 0}) = 6.2 {+-} 1.0 {+-} 0.4, and charge asymmetries {Alpha}{sub ch}(B{sup +} {yields} {omega}{pi}{sup +}) = -0.01 {+-} 0.10 {+-} 0.01 and {Alpha}{sub ch}(B{sup +} {yields} {omega}K{sup +}) = 0.05 {+-} 0.09 {+-} 0.01.
Date:
March 23, 2006
Creator:
Aubert, B.
Object Type:
Report
System:
The UNT Digital Library
Time-dependent Force-free Pulsar Magnetospheres: Axisymmetric and Oblique Rotators
Magnetospheres of many astrophysical objects can be accurately described by the low-inertia (or ''force-free'') limit of MHD. We present a new numerical method for solution of equations of force-free relativistic MHD based on the finite-difference time-domain (FDTD) approach with a prescription for handling spontaneous formation of current sheets. We use this method to study the time-dependent evolution of pulsar magnetospheres in both aligned and oblique magnetic geometries. For the aligned rotator we confirm the general properties of the time-independent solution of Contopoulos et al. (1999). For the oblique rotator we present the 3D structure of the magnetosphere and compute, for the first time, the spindown power of pulsars as a function of inclination of the magnetic axis. We find the pulsar spindown luminosity to be L {approx} ({mu}{sup 2}{Omega}{sub *}{sup 4}/c{sup 3})(1 + sin{sup 2}{alpha}) for a star with the dipole moment {mu}, rotation frequency {Omega}{sub *}, and magnetic inclination angle {alpha}. We also discuss the effects of current sheet resistivity and reconnection on the structure and evolution of the magnetosphere.
Date:
April 10, 2006
Creator:
Spitkovsky, Anatoly
Object Type:
Report
System:
The UNT Digital Library
POWDER METALLURGY TiAl ALLOYS: MICROSTRUCTURES AND PROPERTIES
The microstructures and properties of powder metallurgy TiAl alloys fabricated by hot extrusion of gas-atomized powder at different elevated temperatures were investigated. Microstructure of the alloy fabricated at 1150 C consisted of a mixture of fine ({gamma} + {alpha}{sub 2}) equiaxed grains and coarse ordered B2 grains. Particles of ordered hexagonal {omega} phase were also observed in some B2 grains. The alloy containing B2 grains displayed a low-temperature superplastic behavior: a tensile elongation of 310% was measured when the alloy was tested at 800 C under a strain rate of 2 x 10{sup -5} s{sup -1}. Microstructure of the alloy fabricated at 1250 C consisted of a mixture of fine ({gamma} + {alpha}{sub 2}) equiaxed grains, coarse {alpha}{sub 2} grains, and lamellar ({gamma} + {alpha}{sub 2}) colonies. An observation of stacking faults associated with fine {gamma} lamellae in {alpha}{sub 2} grains reveals that the stacking fault of {alpha}{sub 2} phase plays an important role in the formation of lamellar ({gamma} + {alpha}{sub 2}) colonies. Unlike the alloy fabricated at 1150{sup o}, the alloy fabricated at 1250{sup o} displayed no low-temperature superplasticity, but a tensile elongation of 260% at 1000 C was measured. Microstructure of the alloy fabricated at 1400 C …
Date:
December 11, 2006
Creator:
Hsiung, L
Object Type:
Article
System:
The UNT Digital Library
Development of Improved Chemicals and Plastics from Oilseeds
The overall objective of this program was to develop technology that can be applied to the production of various chemicals and plastics from seed oils. This research and development program included activities in all four key barrier areas identified in the US DOE Technology Roadmap for Plant/Crop-Based Renewable Resources, namely Plant Science, Production, Processing, and Utilization. Participants in the project included The Dow Chemical Company, Castor Oil, Inc., and the USDA Western Regional Research Center (WRRC). The objective of this production task was to evaluate and develop metathesis catalyst technology as a means of utilizing seed oils as feedstocks for the chemical industry. Specifically, ethenolysis of fatty acid methyl esters, FAME’s, leads to functionalized derivatives. These serve as valuable starting points for materials which cascade into a variety of applications, many of which have a current market presence. The relatively recent discovery and commercial availability of a family of metathesis catalysts which are tolerant of polar functional groups and the acquisition and implementation of high throughput synthesis and screening infrastructure led to a prime opportunity to investigate this project area.
Date:
November 9, 2006
Creator:
Nugent, Patricia A. & Lysenko, Zenon
Object Type:
Report
System:
The UNT Digital Library
New constraints on neutrino masses from cosmology
By combining data from cosmic microwave background (CMB) experiments (including the recent WMAP third year results), large scale structure (LSS) and Lyman-{alpha} forest observations, we derive upper limits on the sum of neutrino masses of {summation}m{sub v} < 0.17eV at 95% c.l.. We then constrain the hypothesis of a fourth, sterile, massive neutrino. For the 3 massless + 1 massive neutrino case we bound the mass of the sterile neutrino to m{sub s} < 0.26eV at 95% c.l.. These results exclude at high significance the sterile neutrino hypothesis as an explanation of the LSND anomaly. We then generalize the analysis to account for active neutrino masses which tightens the limit to m{sub s} < 0.23eV and the possibility that the sterile abundance is not thermal. In the latter case, the constraints in the (mass, density) plane are nontrivial. For a mass of > 1eV or < 0.05eV the cosmological energy density in sterile neutrinos is always constrained to be {omega}{sub v} < 0.003 at 95% c.l.. However, for a sterile neutrino mass of {omega}{sub v} 0.25eV, {omega}{sub v} can be as large as 0.01.
Date:
January 1, 2006
Creator:
Melchiorri, A.; Serra, P.; Dodelson, S. & Slosar, A.
Object Type:
Article
System:
The UNT Digital Library
Power Corrections in Charmless Nonleptonic B Decays: Annihilationis Factorizable and Real
We classify {Lambda}{sub QCD}/m{sub b} power corrections to nonleptonic B {yields} M{sub 1}M{sub 2} decays, where M{sub 1,2} are charmless non-isosinglet mesons. Using recent developments in soft-collinear effective theory, we prove that the leading contributions to annihilation amplitudes of order {alpha}{sub s}(m{sub b}) {Lambda}{sub QCD}/m{sub b} are real. The leading annihilation amplitudes depend on twist-2 and the twist-3 three parton distributions. A complex nonperturbative parameter from annihilation first appears at {Omega}[{alpha}{sub s}{sup 2}({radical}{Lambda}m{sub b}){Lambda}{sub QCD}/m{sub b}]. 'Chirally enhanced' contributions are also factorizable and real at lowest order. Thus, incalculable strong phases are suppressed in annihilation amplitudes, unless the {alpha}{sub s}({radical}{Lambda}m{sub b}) expansion breaks down. Modeling the distribution functions, we find that (11 {+-} 9)% and (15 {+-} 11)% of the absolute values of the measured {bar B}{sup 0} {yields} K{sup -}{pi}{sup +} and B{sup -} {yields} K{sup -}K{sup 0} penguin amplitudes come from annihilation. This is consistent with the expected size of power corrections.
Date:
October 10, 2006
Creator:
Arnesen, Christian M.; Ligeti, Zoltan; Rothstein, Ira Z. & Stewart, Iain W.
Object Type:
Article
System:
The UNT Digital Library
Rediscovery of the Elements: Aluminum
Article describing the history of aluminum, from its use in alum to its isolation. Tourist information is given regarding locations pertinent to aluminum.
Date:
Summer 2006
Creator:
Marshall, James L., 1940- & Marshall, Virginia R.
Object Type:
Article
System:
The UNT Digital Library
Rediscovery of the Elements: Fluorine
Article describing the isolation of elemental fluorine. Tourist information is given regarding locations pertinent to the element's history.
Date:
Autumn 2006
Creator:
Marshall, James L., 1940- & Marshall, Virginia R.
Object Type:
Article
System:
The UNT Digital Library
Interpolation of probability densities in ENDF and ENDL
Suppose that we are given two probability densities p{sub 0}(E{prime}) and p{sub 1}(E{prime}) for the energy E{prime} of an outgoing particle, p{sub 0}(E{prime}) corresponding to energy E{sub 0} of the incident particle and p{sub 1}(E{prime}) corresponding to incident energy E{sub 1}. If E{sub 0} < E{sub 1}, the problem is how to define p{sub {alpha}}(E{prime}) for intermediate incident energies E{sub {alpha}} = (1 - {alpha})E{sub 0} + {alpha}E{sub 1} with 0 < {alpha} < 1. In this note the author considers three ways to do it. They begin with unit-base interpolation, which is standard in ENDL and is sometimes used in ENDF. They then describe the equiprobable bins used by some Monte Carlo codes. They then close with a discussion of interpolation by corresponding-points, which is commonly used in ENDF.
Date:
January 27, 2006
Creator:
Hedstrom, G
Object Type:
Report
System:
The UNT Digital Library
Studies of electron and proton isochoric heating for fast ignition
Isochoric heating of inertially confined fusion plasmas by laser driven MeV electrons or protons is an area of great topical interest in the inertial confinement fusion community, particularly with respect to the fast ignition (FI) proposal to use this technique to initiate burn in a fusion capsule. Experiments designed to investigate electron isochoric heating have measured heating in two limiting cases of interest to fast ignition, small planar foils and hollow cones. Data from Cu K{alpha} fluorescence, crystal x-ray spectroscopy of Cu K shell emission, and XUV imaging at 68eV and 256 eV are used to test PIC and Hybrid PIC modeling of the interaction. Isochoric heating by focused proton beams generated at the concave inside surface of a hemi-shell and from a sub hemi-shell inside a cone have been studied with the same diagnostic methods plus imaging of proton induced K{alpha}. Conversion efficiency to protons has also been measured and modeled. Conclusions from the proton and electron heating experiments will be presented. Recent advances in modeling electron transport and innovative target designs for reducing igniter energy and increasing gain curves will also be discussed.
Date:
October 2, 2006
Creator:
Mackinnon, A.; Key, M.; Akli, K.; Beg, F.; Clarke, R.; Clarke, D. et al.
Object Type:
Article
System:
The UNT Digital Library
Solid-Density Plasma characterization with X-ray scattering on the 200-J Janus Laser
We present collective x-ray scattering (CXS) measurements using a Chlorine He-{alpha} x-ray source pumped with less than 200 J of laser energy. The experimental scattering spectra show plasmon resonances from shocked samples. These experiments use only 10{sup 12} x-ray photons at the sample of which 10{sup -5} have been scattered and detected with a highly efficient curved crystal spectrometer. Our results demonstrate that x-ray scattering is a viable technique on smaller laser facilities making CXS measurements accessible to a broad scientific community.
Date:
April 25, 2006
Creator:
Neumayer, P B; Gregori, G; Ravasio, A; Price, D; Bastea, M; Landen, O L et al.
Object Type:
Article
System:
The UNT Digital Library
Gamow-Teller Strength in the A=14 Multiplet: A Challenge to the Shell Model
A new experimental approach to the famous problem of the anomalously slow Gamow-Teller (GT) transitions in the {beta} decay of the A = 14 multiplet is presented. The GT strength distributions to excited states in {sup 14}C and {sup 14}O was studied in high-resolution (d,{sup 2}He) and ({sup 3}He,t) charge-exchange reactions on {sup 14}N. No-core shell-model (NCSM) calculations capable of reproducing the suppression of the {beta} decays predict a selective excitation of J{sup {pi}} = 2{sup +} states. The experimental confirmation represents a validation of the assumptions about the underlying structure of the {sup 14}N ground state wave function. However, the fragmentation of the GT strength over three 2{sup +} final states remains a fundamental issue not explained by the present NCSM using a 6 {h_bar}{omega} model space, suggesting possibly the need to include cluster structure in these light nuclei in a consistent way.
Date:
August 7, 2006
Creator:
Negret, A.; Adachi, T.; Barrett, B. R.; Baumer, C.; den Berg, A. V.; Berg, G. et al.
Object Type:
Article
System:
The UNT Digital Library
Integrated Laser-Target Interaction Experiments on the RAL Petawatt Laser
Since the construction of the first Petawatt laser on the Nova laser facility at Lawrence Livermore National Laboratory we are witnessing the emergence of similar Petawatt-class laser systems at laboratories all around the world. This new generation of lasers, able to deliver several hundred joules of energy in a sub-picosecond pulse, has enabled a host of new discoveries to be made and continues to provide a valuable tool to explore new regimes in relativistic laser-plasma physics--encompassing high energy X-rays and -rays, relativistic electrons, intense ion beams, and superstrong magnetic fields. The coupling in the near-future of multi-kiloJoule Petawatt-class lasers with large-scale fusion lasers.including the NIF and Omega EP (US), LIL (France), and FIREX (Japan)--will further expand opportunities in fast ignition, high energy X-ray radiography, and high energy density physics research. The 500 J Petawatt laser at the Rutherford Appleton Laboratory is currently the highest energy short-pulse laser in the world. In this paper we describe a recent experimental campaign carried out on the facility. The campaign, performed by a large collaborative team from eight different laboratories, was designed to study a variety of relativistic laser-interaction phenomena including laser absorption, fast electron transport, proton heating, and high-brightness x-ray generation. The wide …
Date:
October 11, 2006
Creator:
Patel, P. K.; Key, M. H.; Mackinnon, A. J.; Berry, R.; Borghesi, M.; Chambers, D. M. et al.
Object Type:
Article
System:
The UNT Digital Library
Prickly Pear, Yearbook of Abilene Christian University, 2006
Yearbook for Abilene Christian University in Abilene, Texas includes photos of and information about the school, student body, professors, and organizations. Index starts on page 256. This volume includes a DVD.
Date:
2006
Creator:
Abilene Christian University
Object Type:
Yearbook
System:
The Portal to Texas History
[Program: The Author's Talk]
Program for a lecture featuring author Bill Carpenter produced by the Black Academy of Arts and Letters on April 8, 2006 at the Clarence Muse Cafe Theatre.
Date:
April 2006
Creator:
Black Academy of Arts and Letters
Object Type:
Pamphlet
System:
The UNT Digital Library
[Program: Literary Voice Series]
Program for a conference featuring author Mari Evans hosted by the Black Academy of Arts and Letters on March 4, 2006 at the Dallas Convention Center Theatre.
Date:
March 2006
Creator:
Black Academy of Arts and Letters
Object Type:
Pamphlet
System:
The UNT Digital Library
[Program: Chit-Chat Between Two Writers: An African-American and Caribbean Dialogue]
Program for an event featuring a discussion and lecture between two writers hosted by the Black Academy of Arts and Letters on June 10, 2006 at the Clarence Muse Cafe Theatre.
Date:
June 2006
Creator:
Black Academy of Arts and Letters
Object Type:
Pamphlet
System:
The UNT Digital Library
[Program: Poets and Jazz #2]
Program for a poetry and jazz event produced by the Black Academy of Arts and Letters on May 5-6, 2006 at the Clarence Muse Cafe Theatre.
Date:
May 2006
Creator:
Black Academy of Arts and Letters
Object Type:
Pamphlet
System:
The UNT Digital Library