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Measurement of Branching Fractions of Radiative Charm Decays

Description: We present a measurement of the branching fractions for the Cabibbo-favored radiative decay, D{sup 0} {yields} {bar K}*{sup 0}{gamma}, and the Cabibbo-suppressed radiative decay, D{sup 0} {yields} {phi}{gamma}. These measurements are based on a data sample corresponding to an integrated luminosity of 387.1 fb{sup -1}, recorded with the BABAR detector at the PEP-II e{sup +}e{sup -} asymmetric-energy collider operating at center-of-mass energies 10.58 and 10.54 GeV. We measure the branching fract… more
Date: August 18, 2008
Creator: Aubert, B.
Partner: UNT Libraries Government Documents Department
open access

The energy dependence of the total charm cross section

Description: We discuss the energy dependence of the total charm cross section and some of its theoretical uncertainties including the quark mass, scale choice and the parton densities. We compare the next-to-leading order calculation of the total cross section with results obtained using PYTHIA.
Date: October 18, 2007
Creator: Vogt, R
Partner: UNT Libraries Government Documents Department
open access

Measurements and Modeling of Coherent Synchrotron Radiation and its Impact on the LCLS Electron Beam

Description: In order to reach the high peak current required for an x-ray free electron laser, two separate magnetic dipole chicanes are used in the Linac Coherent Light Source (LCLS) accelerator to compress the electron bunch length in stages. In these bunch compressors, coherent synchrotron radiation (CSR) can be emitted either by a short electron bunch or by any longitudinal density modulation that may be on the bunch. In this paper, we report detailed measurements of the CSR-induced energy loss and tra… more
Date: December 18, 2008
Creator: Bane, K. L. F.; Decker, F. J.; Ding, Y.; Dowell, D.; Emma, P.; Frisch, J. et al.
Partner: UNT Libraries Government Documents Department
open access

Pump and probe damage testing for investigation of transient material modifications associated with laser damage in optical materials

Description: Laser-induced breakdown in the bulk of transparent dielectric materials is associated with the generation of extreme localized conditions of temperatures and pressures. In this work, we perform pump and probe damage testing experiments to investigate the evolution of transient absorption by the host material arising from modifications following confined laser energy deposition in fused silica and DKDP materials. Specifically, we measure the size of the damage sites observed in the region of spa… more
Date: October 18, 2007
Creator: Negres, R A; Feit, M D; DeMange, P; Bude, J D & Demos, S G
Partner: UNT Libraries Government Documents Department
open access

Microwave Transmission Measurements of the Electron Cloud density In the Positron Ring of PEP-II

Description: Clouds of electrons in the vacuum chambers of accelerators of positively charged particle beams present a serious limitation for operation of these machines at high currents. Because of the size of these accelerators, it is difficult to probe the low energy electrons clouds over substantial lengths of the beam pipe. We applied a novel technique to directly measure the electron cloud density via the phase shift induced in a TE wave which is independently excited and transmitted over a straight s… more
Date: June 18, 2008
Creator: Pivi, Mauro T.F.; Krasnykh, Anatoly K.; Byrd, John; De Santis, Stefano; Sonnaad, Kiran G.; Caspers, Fritz et al.
Partner: UNT Libraries Government Documents Department
open access

Isothermal Martensitic and Pressure-Induced Delta to Alpha-Prime Phase Transformations in a Pu-Ga Alloy

Description: A well-homogenized Pu-2 at.% Ga alloy can be retained in the metastable face-centered cubic {delta} phase at room temperature. Ultimately, this metastable {delta} phase will decompose via a eutectoid transformation to the thermodynamically stable monoclinic {alpha} phase and the intermetallic compound Pu{sub 3}Ga over a period of approximately 10,000 years [1]. In addition, these low solute-containing {delta}-phase Pu alloys are metastable with respect to an isothermal martensitic phase transfo… more
Date: January 18, 2008
Creator: Schwartz, A J; Wall, M A; Farber, D L; Moore, K T & Blobaum, K M
Partner: UNT Libraries Government Documents Department
open access

A High-Order Finite-Volume Algorithm for Fokker-Planck Collisions in Magnetized Plasmas

Description: A high-order finite volume algorithm is developed for the Fokker-Planck Operator (FPO) describing Coulomb collisions in strongly magnetized plasmas. The algorithm is based on a general fourth-order reconstruction scheme for an unstructured grid in the velocity space spanned by parallel velocity and magnetic moment. The method provides density conservation and high-order-accurate evaluation of the FPO independent of the choice of the velocity coordinates. As an example, a linearized FPO in const… more
Date: April 18, 2007
Creator: Xiong, Z; Cohen, R H; Rognlien, T D & Xu, X Q
Partner: UNT Libraries Government Documents Department
open access

2007 Archaea: Ecology, Metabolism and Molecular Biology

Description: The Archaea are a fascinating and diverse group of prokaryotic organisms with deep roots overlapping those of eukaryotes. The focus of this GRC conference, 'Archaea: Ecology Metabolism & Molecular Biology', expands on a number of emerging topics highlighting the evolution and composition of microbial communities and novel archaeal species, their impact on the environment, archaeal metabolism, and research that stems from sequence analysis of archaeal genomes. The strength of this conference lie… more
Date: September 18, 2008
Creator: Gray, Imke Schroeder Nancy Ryan
Partner: UNT Libraries Government Documents Department
open access

Catalyzed Water Oxidation by Solar Irradiation of Band-Gap-Narrowed Semiconductors (Part 2. Overview).

Description: The objectives of this report are: (1) Investigate the catalysis of water oxidation by cobalt and manganese hydrous oxides immobilized on titania or silica nanoparticles, and dinuclear metal complexes with quinonoid ligands in order to develop a better understanding of the critical water oxidation chemistry, and rationally search for improved catalysts. (2) Optimize the light-harvesting and charge-separation abilities of stable semiconductors including both a focused effort to improve the best … more
Date: March 18, 2008
Creator: Fujita, E.; Khalifah, P.; Lymar, S.; Muckerman, J. T. & Rodriguez, J.
Partner: UNT Libraries Government Documents Department
open access

Modeling Incoherent Electron Cloud Effects

Description: Incoherent electron effects could seriously limit the beam lifetime in proton or ion storage rings, such as LHC, SPS, or RHIC, or blow up the vertical emittance of positron beams, e.g., at the B factories or in linear-collider damping rings. Different approaches to modeling these effects each have their own merits and drawbacks. We describe several simulation codes which simplify the descriptions of the beam-electron interaction and of the accelerator structure in various different ways, and pr… more
Date: June 18, 2007
Creator: Vay, Jean-Luc; Benedetto, E.; Fischer, W.; Franchetti, G.; Ohmi, K.; Schulte, D. et al.
Partner: UNT Libraries Government Documents Department
open access

CORROSION OF LEAD SHIELDING IN NUCLEAR MATERIALS PACKAGES

Description: Inspection of United States-Department of Energy (US-DOE) model 9975 nuclear materials shipping package revealed corrosion of the lead shielding that was induced by off-gas constituents from organic components in the package. Experiments were performed to determine the corrosion rate of lead when exposed to off-gas or degradation products of these organic materials. The results showed that the room temperature vulcanizing (RTV) sealant was the most corrosive organic species used in the construc… more
Date: July 18, 2008
Creator: Subramanian, K; Kerry Dunn, K & Joseph Murphy, J
Partner: UNT Libraries Government Documents Department
open access

Temperature dependence of protein hydration hydrodynamics by molecular dynamics simulations.

Description: The dynamics of water molecules near the protein surface are different from those of bulk water and influence the structure and dynamics of the protein itself. To elucidate the temperature dependence hydration dynamics of water molecules, we present results from the molecular dynamic simulation of the water molecules surrounding two proteins (Carboxypeptidase inhibitor and Ovomucoid) at seven different temperatures (T=273 to 303 K, in increments of 5 K). Translational diffusion coefficients of … more
Date: July 18, 2007
Creator: Lau, E Y & Krishnan, V V
Partner: UNT Libraries Government Documents Department
open access

Dielectric Wall Accelerator Technology

Description: The dielectric wall accelerator (DWA) is a compact pulsed power device where the pulse forming lines, switching, and vacuum wall are integrated into a single compact geometry. For this effort, we initiated a extensive compact pulsed power development program and have pursued the study of switching (gas, oil, laser induced surface flashover and photoconductive), dielectrics (ceramics and nanoparticle composites), pulse forming line topologies (asymmetric and symmetric Blumleins and zero integral… more
Date: October 18, 2007
Creator: Sampayan, S.; Caporaso, G.; Chen, Y.; Harris, J.; Hawkins, S.; Holmes, C. et al.
Partner: UNT Libraries Government Documents Department
open access

Star-Formation in Low Radio Luminosity AGN from the Sloan Digital Sky Survey

Description: We investigate faint radio emission from low- to high-luminosity Active Galactic Nuclei (AGN) selected from the Sloan Digital Sky Survey (SDSS). Their radio properties are inferred by coadding large ensembles of radio image cut-outs from the FIRST survey, as almost all of the sources are individually undetected. We correlate the median radio flux densities against a range of other sample properties, including median values for redshift, [O III] luminosity, emission line ratios, and the strength… more
Date: April 18, 2007
Creator: de Vries, W. H.; Hodge, J. A.; Becker, R. H.; White, R. L. & Helfand, D. J.
Partner: UNT Libraries Government Documents Department
open access

Enhancing Price Response Programs through Auto-DR: California's 2007 Implementation Experience

Description: This paper describes automated demand response (Auto-DR) activities, an innovative effort in California to ensure that DR programs produce effective and sustainable impacts. Through the application of automation and communication technologies coupled with well-designed incentives and DR programs such as Critical Peak Pricing (CPP) and Demand Bidding (DBP), Auto-DR is opening up the opportunity for many different types of buildings to effectively participate in DR programs. We present the result… more
Date: December 18, 2007
Creator: Kiliccote, Sila; Wikler, Greg; Chiu, Albert; Piette, Mary Ann; Kiliccote, Sila; Hennage, Dan et al.
Partner: UNT Libraries Government Documents Department
open access

Bi3+ Luminescence in ABiO2Cl (A = Sr, Ba) and BaBiO2Br

Description: Trivalent bismuth luminescence is reported in three Sillenbismuth oxyhalide phases, SrBiO2Cl, BaBiO2Cl, and BaBiO2Br. Thesecompounds exhibit Bi 6s6->6 s2 emission under UV and X-ray radiation.At room temperature, BaBiO2Cl shows the most intense light emission, withspectral and decay properties similar to those found in Bi4Ge3O12 (BGO).At low temperatures, each phase show an increase in the photoluminescenceintensities and a narrowing of the emission peaks. In contrast to thetemperature dependen… more
Date: January 18, 2007
Creator: Porter-Chapman, Yetta D.; Bourret-Courchesne, Edith E. & Derenzo,Stephen E.
Partner: UNT Libraries Government Documents Department
open access

Hydrogen adsorption on Ru(001) studied by Scanning TunnelingMicroscopy

Description: The adsorption of hydrogen on Ru(001) was studied by scanning tunneling microscopy at temperatures around 50 K. Hydrogen was found to adsorb dissociatively forming different ordered structures as a function of coverage. In order of increasing coverage {theta} in monolayers (ML) these were ({radical}3 x {radical}3)r30{sup o} at {theta} = 0.3 ML; (2 x 1) at {theta} = 0.50 ML, (2 x 2)-3H at {theta} = 0.75, and (1 x 1) at {theta} = 1.00. Some of these structures were observed to coexist at intermed… more
Date: January 18, 2008
Creator: Tatarkhanov, Mous; Rose, Franck; Fomin, Evgeny; Ogletree, D.Frank & Salmeron, Miquel
Partner: UNT Libraries Government Documents Department
open access

Hadronic B Decays to Charm and Charmonium With the BaBar Experiment

Description: The BABAR experiment has recorded the decays of more than 465 x 10{sup 6} B{bar B} pairs since 1999, and is reaching an unprecedented precision in the measurement of hadronic B decays. The following results are presented: tests of QCD factorization with the decays B {yields} {chi}{sub c0}K*, B {yields} {chi}{sub c1,2}K{sup (*)}, and {bar B}{sup 0} {yields} D{sup (*)0}h{sup 0}, h{sup 0} = {pi}{sup 0}, {eta}, {omega}, {eta}{prime}, study of the decays to charmonium B {yields} {eta}{sub c}K{sup (*… more
Date: September 18, 2008
Creator: Prudent, Xavier
Partner: UNT Libraries Government Documents Department
open access

Simulating mixed-phase Arctic stratus clouds: sensitivity to ice initiation mechanisms

Description: The importance of Arctic mixed-phase clouds on radiation and the Arctic climate is well known. However, the development of mixed-phase cloud parameterization for use in large scale models is limited by lack of both related observations and numerical studies using multidimensional models with advanced microphysics that provide the basis for understanding the relative importance of different microphysical processes that take place in mixed-phase clouds. To improve the representation of mixed-phas… more
Date: February 18, 2008
Creator: Sednev, Igor; Sednev, I.; Menon, S. & McFarquhar, G.
Partner: UNT Libraries Government Documents Department
open access

Evidence of half-metallic interface magnetism via local moment formation in Co based Heusler alloys

Description: In this work we use a combination of x-ray magnetic circular and linear dichroism (XMCD and XMLD) techniques to examine the formation of local moments in Heusler alloys of the composition Co{sub 2}MnX (where X=Si or Al). The existence of local moments in a half-metallic system is reliant upon the band gap in the minority-spin states. By utilizing the element-specific nature of x-ray techniques we are able to explore the origin of the minority-spin band gap in the partial density of states (PDOS… more
Date: August 18, 2008
Creator: Telling, N. D.; Keatley, P. S.; van der Laan, G.; Hicken, R. J.; Arenholz, E.; Sakuraba, Y. et al.
Partner: UNT Libraries Government Documents Department
open access

Preliminary Benchmarking Efforts and MCNP Simulation Results for Homeland Security

Description: It is shown in this work that basic measurements made from well defined source detector configurations can be readily converted in to benchmark quality results by which Monte Carlo N-Particle (MCNP) input stacks can be validated. Specifically, a recent measurement made in support of national security at the Nevada Test Site (NTS) is described with sufficient detail to be submitted to the American Nuclear Society’s (ANS) Joint Benchmark Committee (JBC) for consideration as a radiation measuremen… more
Date: April 18, 2008
Creator: Hayes, Robert
Partner: UNT Libraries Government Documents Department
open access

Light-Front Holography and Novel Effects in QCD

Description: The correspondence between theories in anti-de Sitter space and conformal field theories in physical space-time leads to an analytic, semiclassical model for strongly-coupled QCD. Light-front holography allows hadronic amplitudes in the AdS fifth dimension to be mapped to frame-independent light-front wavefunctions of hadrons in physical space-time, thus providing a relativistic description of hadrons at the amplitude level. We identify the AdS coordinate z with an invariant light-front coordin… more
Date: December 18, 2008
Creator: Brodsky, Stanley J. & de Teramond, Guy F.
Partner: UNT Libraries Government Documents Department
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