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Sulfidation of Cadmium at the Nanoscale

Description: We investigate the evolution of structures that result when spherical Cd nanoparticles of a few hundred nanometers in diameter react with dissolved molecular sulfur species in solution to form hollow CdS. Over a wide range of temperatures and concentrations, we find that rapid Cd diffusion through the growing CdS shell localizes the reaction front at the outermost CdS/S interface, leading to hollow particles when all the Cd is consumed. When we examine partially reacted particles, we find that … more
Date: May 22, 2008
Creator: Cabot, Andreu; Smith, Rachel; Yin, Yadong; Zheng, Haimei; Reinhard, Bjorn; Liu, Haitao et al.
Partner: UNT Libraries Government Documents Department
open access

To Crack or Not to Crack: Strain in High TemperatureSuperconductors

Description: Round wire Bi 2212 is emerging as a viable successor ofNb3Sn in High Energy Physics and Nuclear Magnetic Resonance, to generatemagnetic fields that surpass the intrinsic limitations of Nb3Sn. Ratherbold claims are made on achievable magnetic fields in applications usingBi 2212, due to the materials' estimated critical magnetic field of 100 Tor higher. High transport currents in high magnetic fields, however, leadto large stress on, and resulting large strain in the superconductor. Theeffect of … more
Date: August 22, 2007
Creator: Godeke, Arno
Partner: UNT Libraries Government Documents Department
open access

A high-throughput contact-hole resolution metric for photoresists:Full-process sensitivity study

Description: The ability to accurately quantify the intrinsic resolution of chemically amplified photoresists is critical for the optimization of resists for extreme ultraviolet (EUV) Iithography. We have recently reported on two resolution metrics that have been shown to extract resolution numbers consistent with direct observation. In this paper we examine the previously reported contact-hole resolution metric and explore the sensitivity of the metric to potential error sources associated with the experim… more
Date: January 22, 2008
Creator: Anderson, Christopher N. & Naulleau, Patrick P.
Partner: UNT Libraries Government Documents Department
open access

TANK FARM RETRIEVAL LESSONS LEARNED AT THE HANFORD SITE

Description: One of the environmental remediation challenges facing the nation is the retrieval and permanent disposal of approximately 90 million gallons of radioactive waste stored in underground tanks at the U. S. Department of Energy (DOE) facilities. The Hanford Site is located in southeastern Washington State and stores roughly 60 percent of this waste. An estimated 53 million gallons of high-level, transuranic, and low-level radioactive waste is stored underground in 149 single-shell tanks (SSTs) and… more
Date: January 22, 2008
Creator: RA, DODD
Partner: UNT Libraries Government Documents Department
open access

The Third Image of the Large-Separation Lensed Quasar SDSS J1029+2623

Description: We identify a third image in the unique quasar lens SDSS J1029+2623, the second known quasar lens produced by a massive cluster of galaxies. The spectrum of the third image shows similar emission and absorption features, but has a redder continuum than the other two images which can be explained by differential extinction or microlensing. We also identify several lensed arcs. Our observations suggest a complicated structure of the lens cluster at z {approx} 0.6. We argue that the three lensed i… more
Date: February 22, 2008
Creator: Oguri, Masamune; Ofek, Eran O.; Inada, Naohisa; Morokuma, Tomoki; Falco, Emilio E.; Kochanek, Christopher S. et al.
Partner: UNT Libraries Government Documents Department
open access

Sum Frequency Generation Vibrational Spectroscopy of Pyridine Hydrogenation on Platinum Nanoparticles

Description: Pyridine hydrogenation in the presence of a surface monolayer consisting of cubic Pt nanoparticles stabilized by tetradecyltrimethylammonium bromide (TTAB) was investigated by sum frequency generation (SFG) vibrational spectroscopy using total internal reflection (TIR) geometry. TIR-SFG spectra analysis revealed that a pyridinium cation (C{sub 5}H{sub 5}NH{sup +}) forms during pyridine hydrogenation on the Pt nanoparticle surface, and the NH group in the C{sub 5}H{sub 5}NH{sup +} cation becomes… more
Date: February 22, 2008
Creator: Bratlie, Kaitlin M.; Komvopoulos, Kyriakos & Somorjai, Gabor A.
Partner: UNT Libraries Government Documents Department
open access

Dissipative Cryogenic Filters with Zero DC Resistance

Description: The authors designed, implemented and tested cryogenic RF filters with zero DC resistance, based on wires with a superconducting core inside a resistive sheath. The superconducting core allows low frequency currents to pass with negligible dissipation. Signals above the cutoff frequency are dissipated in the resistive part due to their small skin depth. The filters consist of twisted wire pairs shielded with copper tape. Above approximately 1 GHz, the attenuation is exponential in {radical}{ome… more
Date: April 22, 2008
Creator: Bluhm, Hendrik; Moler, Kathryn A. & /Stanford U., Appl. Phys. Dept
Partner: UNT Libraries Government Documents Department
open access

ENVIRONMENTAL SAMPLING AND ANALYSIS - GETTING IT RIGHT

Description: The Department of Energy's Hanford Site in southeastern Washington State was established in the 1940s as part of the Manhattan Project. Hanford's role was to produce weapons-grade nuclear material for defense, and by 1989, when the Site's mission changed from operations to cleanup, Hanford had produced more than 60 percent of the nation's plutonium. The legacy of Hanford's production years is enormous in terms of nuclear and hazardous waste, especially the 270 billion gallons of contaminated gr… more
Date: January 22, 2008
Creator: CW, CONNELL
Partner: UNT Libraries Government Documents Department
open access

Information Resources in High-Energy Physics: Surveying the Present Landscape and Charting the Future Course

Description: Access to previous results is of paramount importance in the scientific process. Recent progress in information management focuses on building e-infrastructures for the optimization of the research workflow, through both policy-driven and user-pulled dynamics. For decades, High-Energy Physics (HEP) has pioneered innovative solutions in the field of information management and dissemination. In light of a transforming information environment, it is important to assess the current usage of informa… more
Date: April 22, 2008
Creator: Gentil-Beccot, Anne; Mele, Salvatore; Holtkamp, Annette; O'Connell, Heath B. & Brooks, Travis C.
Partner: UNT Libraries Government Documents Department
open access

Characterizing the nano and micro structure of concrete to improve its durability

Description: New and advanced methodologies have been developed to characterize the nano and microstructure of cement paste and concrete exposed to aggressive environments. High resolution full-field soft X-ray imaging in the water window is providing new insight on the nano scale of the cement hydration process, which leads to a nano-optimization of cement-based systems. Hard X-ray microtomography images on ice inside cement paste and cracking caused by the alkali-silica reaction (ASR) enables three-dimens… more
Date: October 22, 2008
Creator: Monteiro, P. J. M.; Kirchheim, A. P.; Chae, S.; Fischer, P.; MacDowell, A. A.; Schaible, E. et al.
Partner: UNT Libraries Government Documents Department
open access

ECLOUD in PS2, PS+, SPS+: AN UPDATE

Description: We present an update of our results for the electron-cloud build-up for several upgrades proposed for the LHC injectors. Specifically, we have re-examined our published results for the ecloud heat load [1] from the perspective of numerical convergence of the simulations vis-a-vis the integration time step {Delta}t. We repeated most of the simulations with ever smaller values of {Delta}t until we reached stable results, indicating numerical convergence; this was achieved at 200-500 slices per bu… more
Date: May 22, 2007
Creator: Furman, M. A.
Partner: UNT Libraries Government Documents Department
open access

Recent Searches for Exotic Physics at the BaBar/PEP-II B-factory

Description: I present three recent results from searches for exotic physics at the BABAR/PEP-II B-factory. These results span many of the samples produced at the B-factory, including B mesons, {tau} leptons, and {Upsilon}(3S) mesons. We have searched for CPT-violation in B{sup 0} mixing and find no significant deviation from the no-violation hypothesis. We have also searched for lepton-flavor-violating decays of the {tau} using {tau}{sup -} {yields} {omega}{ell}{sup -} and {tau}{sup -} {yields} {ell}{sup -… more
Date: October 22, 2008
Creator: Sekula, Stephen Jacob
Partner: UNT Libraries Government Documents Department
open access

Defect Doping of InN

Description: InN films grown by molecular beam epitaxy have been subjected to 2 MeV He{sup +} irradiation followed by thermal annealing. Theoretical analysis of the electron mobilities shows that thermal annealing removes triply charged donor defects, creating films with electron mobilities approaching those predicted for uncompensated, singly charged donors. Optimum thermal annealing of irradiated InN can be used to produce samples with electron mobilities higher than those of as grown films.
Date: July 22, 2007
Creator: Jones, R. E.; van Genuchten, H. C. M.; Yu, K. M.; Walukiewicz, W.; Li, S. X.; A ger III, J. W. et al.
Partner: UNT Libraries Government Documents Department
open access

Black ring deconstruction

Description: We present a sample microstate for a black ring in four and five dimensional language. The microstate consists of a black string microstate with an additional D6-brane. We show that with an appropriate choice of parameters the piece involving the black string microstate falls down a long AdS throat, whose M-theory lift is AdS_3 x S2. We wrap a spinning dipole M2-brane on the S2 in the probe approximation. In IIA, this corresponds to a dielectric D2-brane carrying only D0-charge. We conjecture t… more
Date: June 22, 2007
Creator: Gimon, Eric; Gimon, Eric G. & Levi, Thomas S.
Partner: UNT Libraries Government Documents Department
open access

Observation of B^+\to\eta\rho^+ and Search for B^0 Decays to\eta^\prime\eta, \eta\pi^0, \eta^\prime\pi^0, and \omega\pi^0

Description: The authors present measurements of branching fractions for five B-meson decays to two-body charmless final states. The data, collected with the BABAR detector at the Stanford Linear Accelerator Center, represent 459 million B{bar B} pairs. The results for branching fractions are, in units of 10{sup -6} (upper limits at 90% C.L.): {Beta}(B{sup +} {yields} {eta}{rho}{sup +}) = 9.9 {+-} 1.2 {+-} 0.8, {Beta}(B{sup 0} {yields} {eta}{prime}{eta}) = 0.5 {+-} 0.4 {+-} 0.1 (< 1.2), {Beta}(B{sup 0} {… more
Date: April 22, 2008
Creator: Aubert, Bernard; Bona, Marcella; Karyotakis, Y.; Lees, J. P.; Poireau, V.; Prencipe, E. et al.
Partner: UNT Libraries Government Documents Department
open access

Measurement of the relaxation time of hot electrons in laser-solid interaction at relativistic laser intensities

Description: The authors have measured the relaxation time of hot electrons in short pulse laser-solid interactions using a picosecond time-resolved x-ray spectrometer and a time-integrated electron spectrometer. Employing laser intensities of 10{sup 17}, 10{sup 18}, and 10{sup 19} W/cm{sup 2}, they find increased laser coupling to hot electrons as the laser intensity becomes relativistic and thermalization of hot electrons at timescales on the order of 10 ps at all laser intensities. They propose a simple … more
Date: August 22, 2006
Creator: Chen, H; Shepherd, R; Chung, H K; Dyer, G; Faenov, A; Fournier, K B et al.
Partner: UNT Libraries Government Documents Department
open access

DEVELOPMENT OF AN IMPROVED SODIUM TITANATE FOR THE PRETREATMENT OF NUCLEAR WASTE AT THE SAVANNAH RIVER SITE

Description: High-level nuclear waste produced from fuel reprocessing operations at the Savannah River Site (SRS) requires pretreatment to remove Cs-137, Sr-90 and alpha-emitting radionuclides (i.e., actinides) prior to disposal onsite as low level waste. Separation processes planned at SRS include sorption of Sr-90 and alpha-emitting radionuclides onto monosodium titanate (MST) and caustic side solvent extraction, for Cs-137 removal. The MST and separated Cs-137 will be encapsulated into a borosilicate gla… more
Date: January 22, 2008
Creator: Hobbs, D
Partner: UNT Libraries Government Documents Department
open access

LINAC DESIGN FOR AN ARRAY OF SOFT X-RAY FREE ELECTRON LASERS

Description: The design of the linac delivering electron bunches into ten independent soft x-ray free electron lasers (FELs) producing light at 1 nm and longer wavelengths is presented. The bunch repetition rate in the linac is 1 MHz and 100 kHz in each of ten FEL beam lines. Various issues regarding machine layout and lattice, bunch compression, collimation, and the beam switch yard are discussed. Particular attention is given to collective effects. A demanding goal is to preserve both a low beam slice emi… more
Date: September 22, 2008
Creator: Zholents, Alexander A.; Kur, E.; Penn, G.; Qiang, Ji; Venturini, M. & Wells, R. P.
Partner: UNT Libraries Government Documents Department
open access

PROGRESS IN HANFORDS DOUBLE SHELL TANK (DST) INTEGRITY PROJECT

Description: The U.S. Department of Energy's Office of River Protection has an extensive integrity assessment program for the Hanford Site Double-Shell Tank System. The DOE Orders and environmental protection regulations provide the guidelines for the activities used to inspect and maintain 28 double-shell tanks (DSTs), the waste evaporator, and ancillary equipment that compose this system. This program has been reviewed by oversight and regulatory bodies and found to comply with the established guidelines.… more
Date: January 22, 2008
Creator: HS, BERMAN
Partner: UNT Libraries Government Documents Department
open access

Irreversible volume growth in polymer-bonded powder systems: effects of crystalline anisotropy, particle size distribution, and binder strength

Description: Pressed-powdered crystallites of intrinsically anisotropic materials have been shown to undergo irreversible volume expansion when subjected to repeated cycles of heating and cooling. We develop a coarse-grained (micron-scale) interaction Hamiltonian for this system and perform molecular dynamics simulations, which quantitatively reproduce the experimentally observed irreversible growth. The functional form and values of the interaction parameters at the coarse-grained level are motivated by ou… more
Date: August 22, 2007
Creator: Maiti, A.; Gee, R. H.; Hoffman, D. & Fried, L. E.
Partner: UNT Libraries Government Documents Department
open access

Ion Partitioning at the liquid/vapor interface of a multi-component alkali halidesolution: A model for aqueous sea salt aerosols

Description: The chemistry of Br species associated with sea salt ice and aerosols has been implicated in the episodes of ozone depletion reported at Arctic sunrise. However, Br{sup -} is only a minor component in sea salt, which has a Br{sup -}/Cl{sup -} molar ratio of {approx}0.0015. Sea salt is a complex mixture of many different species, with NaCl as the primary component. In recent years experimental and theoretical studies have reported enhancement of the large, more polarizable halide ion at the liqu… more
Date: December 22, 2008
Creator: Ghosal, Sutapa; Brown, Matthew A.; Bluhm, Hendrik; Krisch, Maria J.; Salmeron, Miquel; Jungwirth, Pavel et al.
Partner: UNT Libraries Government Documents Department
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