Deuterium Retention in NSTX with Lithium Conditioning (open access)

Deuterium Retention in NSTX with Lithium Conditioning

High (≈ 90%) deuterium retention was observed in NSTX gas balance measurements both withand without lithiumization of the carbon plasma facing components. The gas retained in ohmic discharges was measured by comparing the vessel pressure rise after a discharge to that of a gasonly pulse with the pumping valves closed. For neutral beam heated discharges the gas input and gas pumped by the NB cryopanels were tracked. The discharges were followed by outgassing of deuterium that reduced the retention. The relationship between retention and surface chemistry was explored with a new plasma-material interface probe connected to an in-vacuo surface science station that exposed four material samples to the plasma. XPS and TDS analysis showed that the binding of D atoms is fundamentally changed by lithium - in particular atoms are weakly bonded in regions near lithium atoms bound to either oxygen or the carbon matrix.
Date: June 2, 2010
Creator: C.H. Skinner, J.P. Allain, W. Blanchard, H.W. Kugel, R. Maingi, L. Roquemore, V. Soukhanovskii, C.N. Taylor
Object Type: Article
System: The UNT Digital Library
Dynamically tuned high-Q AC-dipole implementation (open access)

Dynamically tuned high-Q AC-dipole implementation

AC-dipole magnets are typically implemented as a parallel LC resonant circuit. To maximize efficiency, it's beneficial to operate at a high Q. This, however, limits the magnet to a narrow frequency range. Current designs therefore operate at a low Q to provide a wider bandwidth at the cost of efficiency. Dynamically tuning a high Q resonant circuit tries to maintain a high efficiency while providing a wide frequency range. The results of ongoing efforts at BNL to implement dynamically tuned high-Q AC dipoles will be presented.
Date: May 2, 2010
Creator: Oddo, P.; Bai, M.; Dawson, W.C.; Meng, W.; Mernick, K.; Pai, C. et al.
Object Type: Article
System: The UNT Digital Library
Dependence of Band Renormalization Effect on the Number of Copper-oxide Layers in Tl-based Copper-oxide Superconductor using Angle-resolved Photoemission Spectroscopy (open access)

Dependence of Band Renormalization Effect on the Number of Copper-oxide Layers in Tl-based Copper-oxide Superconductor using Angle-resolved Photoemission Spectroscopy

Here we report the first angle-resolved photoemission measurement on nearly optimally doped multilayer Tl-based superconducting cuprates (Tl-2212 and Tl-1223) and a comparison study to single-layer (Tl-2201) compound. A kink in the band dispersion is found in all three compounds but exhibits different momentum dependence for the single-layer and multilayer compounds, reminiscent to that of Bi-based cuprates. This layer number dependent renormalization effect strongly implies that the spin-resonance mode is unlikely to be responsible for the dramatic renormalization effect near the antinodal region.
Date: June 2, 2010
Creator: Lee, Wei-Sheng
Object Type: Article
System: The UNT Digital Library
Nodal Quasiparticle in Pseudogapped Colossal Magnetoresistive Manganites (open access)

Nodal Quasiparticle in Pseudogapped Colossal Magnetoresistive Manganites

A characteristic feature of the copper oxide high-temperature superconductors is the dichotomy between the electronic excitations along the nodal (diagonal) and antinodal (parallel to the Cu-O bonds) directions in momentum space, generally assumed to be linked to the d-wave symmetry of the superconducting state. Angle-resolved photoemission measurements in the superconducting state have revealed a quasiparticle spectrum with a d-wave gap structure that exhibits a maximum along the antinodal direction and vanishes along the nodal direction. Subsequent measurements have shown that, at low doping levels, this gap structure persists even in the high-temperature metallic state, although the nodal points of the superconducting state spread out in finite Fermi arcs. This is the so-called pseudogap phase, and it has been assumed that it is closely linked to the superconducting state, either by assigning it to fluctuating superconductivity or by invoking orders which are natural competitors of d-wave superconductors. Here we report experimental evidence that a very similar pseudogap state with a nodal-antinodal dichotomous character exists in a system that is markedly different from a superconductor: the ferromagnetic metallic groundstate of the colossal magnetoresistive bilayer manganite La{sub 1.2}Sr{sub 1.8}Mn{sub 2}O{sub 7}. Our findings therefore cast doubt on the assumption that the pseudogap state …
Date: June 2, 2010
Creator: Mannella, N.
Object Type: Article
System: The UNT Digital Library
Fingerprinting Communication and Computation on HPC Machines (open access)

Fingerprinting Communication and Computation on HPC Machines

How do we identify what is actually running on high-performance computing systems? Names of binaries, dynamic libraries loaded, or other elements in a submission to a batch queue can give clues, but binary names can be changed, and libraries provide limited insight and resolution on the code being run. In this paper, we present a method for"fingerprinting" code running on HPC machines using elements of communication and computation. We then discuss how that fingerprint can be used to determine if the code is consistent with certain other types of codes, what a user usually runs, or what the user requested an allocation to do. In some cases, our techniques enable us to fingerprint HPC codes using runtime MPI data with a high degree of accuracy.
Date: June 2, 2010
Creator: Peisert, Sean
Object Type: Report
System: The UNT Digital Library
Open Automated Demand Response Technologies for Dynamic Pricing and Smart Grid (open access)

Open Automated Demand Response Technologies for Dynamic Pricing and Smart Grid

We present an Open Automated Demand Response Communications Specifications (OpenADR) data model capable of communicating real-time prices to electricity customers. We also show how the same data model could be used to for other types of dynamic pricing tariffs (including peak pricing tariffs, which are common throughout the United States). Customers participating in automated demand response programs with building control systems can respond to dynamic prices by using the actual prices as inputs to their control systems. Alternatively, prices can be mapped into"building operation modes," which can act as inputs to control systems. We present several different strategies customers could use to map prices to operation modes. Our results show that OpenADR can be used to communicate dynamic pricing within the Smart Grid and that OpenADR allows for interoperability with existing and future systems, technologies, and electricity markets.
Date: June 2, 2010
Creator: Ghatikar, Girish; Mathieu, Johanna L.; Piette, Mary Ann & Kiliccote, Sila
Object Type: Article
System: The UNT Digital Library
Open Automated Demand Response Dynamic Pricing Technologies and Demonstration (open access)

Open Automated Demand Response Dynamic Pricing Technologies and Demonstration

This study examines the use of OpenADR communications specification, related data models, technologies, and strategies to send dynamic prices (e.g., real time prices and peak prices) and Time of Use (TOU) rates to commercial and industrial electricity customers. OpenADR v1.0 is a Web services-based flexible, open information model that has been used in California utilities' commercial automated demand response programs since 2007. We find that data models can be used to send real time prices. These same data models can also be used to support peak pricing and TOU rates. We present a data model that can accommodate all three types of rates. For demonstration purposes, the data models were generated from California Independent System Operator's real-time wholesale market prices, and a California utility's dynamic prices and TOU rates. Customers can respond to dynamic prices by either using the actual prices, or prices can be mapped into"operation modes," which can act as inputs to control systems. We present several different methods for mapping actual prices. Some of these methods were implemented in demonstration projects. The study results demonstrate show that OpenADR allows interoperability with existing/future systems/technologies and can be used within related dynamic pricing activities within Smart Grid.
Date: August 2, 2010
Creator: Ghatikar, Girish; Mathieu, Johanna L.; Piette, Mary Ann; Koch, Ed & Hennage, Dan
Object Type: Report
System: The UNT Digital Library
Growth in Biofuels Markets: Long Term Environmental and Socioeconomic Impacts (Final Report) (open access)

Growth in Biofuels Markets: Long Term Environmental and Socioeconomic Impacts (Final Report)

Over the last several years increasing energy and petroleum prices have propelled biofuels and the feedstocks used to produce them, to the forefront of alternative energy production. This growth has increased the linkages between energy and agricultural markets and these changes around the world are having a significant effect on agricultural markets as biofuels begin to play a more substantial role in meeting the world's energy needs. Biofuels are alternatively seen as a means to reduce carbon emissions, increase energy independence, support rural development and to raise farm income. However, concern has arisen that the new demand for traditional commodities or alternative commodities which compete for land can lead to higher food prices and the environmental effects from expanding crop acreage may result in uncertain changes in carbon emissions as land is converted both in the US and abroad. While a number of studies examine changes in land use and consumption from changes in biofuels policies many lack effective policy representation or complete coverage of land types which may be diverted in to energy feedstock production. Many of these biofuels and renewable energy induced land use changes are likely to occur in developing countries with at-risk consumers and on environmentally …
Date: December 2, 2010
Creator: Meyer, Seth D. & Kalaitzandonakes, Nicholas
Object Type: Report
System: The UNT Digital Library
Size-Controlled Synthesis and Optical Properties of Monodisperse Colloidal Magnesium Oxide Nanocrystals (open access)

Size-Controlled Synthesis and Optical Properties of Monodisperse Colloidal Magnesium Oxide Nanocrystals

colloids ? luminescence ? metal oxides ? nanocrystals ? synthesis design
Date: April 2, 2010
Creator: Milliron, Delia J.; Urban, Jeffrey J. & Moon, Hoi Ri
Object Type: Article
System: The UNT Digital Library
A Design Report of the Baseline for PEP-X: an Ultra-Low Emittance Storage Ring (open access)

A Design Report of the Baseline for PEP-X: an Ultra-Low Emittance Storage Ring

Over the past year, we have worked out a baseline design for PEP-X, as an ultra-low emittance storage ring that could reside in the existing 2.2-km PEPII tunnel. The design features a hybrid lattice with double bend achromat (DBA) cells in two arcs and theoretical minimum emittance (TME) cells in the remaining four arcs. Damping wigglers are used to reduce the horizontal emittance to 86 pm-rad at zero current for a 4.5 GeV electron beam. At a design current of 1.5 A, the horizontal emittance increases, due to intrabeam scattering, to 164 pm-rad when the vertical emittance is maintained at a diffraction limited 8 pm-rad. The baseline design will produce photon beams achieving a brightness of 10{sup 22} (ph/s/mm{sup 2}/mrad{sup 2}/0.1% BW) at 10 keV in a 3.5-m conventional planar undulator. Our study shows that an optimized lattice has adequate dynamic aperture, while accommodating a conventional off-axis injection system. In this report, we present the results of study, including the lattice properties, nonlinear dynamics, intra-beam scattering and Touschek lifetime, RF system, and collective instabilities. Finally, we discuss the possibility of partial lasing at soft X-ray wavelengths using a long undulator in a straight section.
Date: June 2, 2010
Creator: Bane, Karl; Bertsche, Kirk; Cai, Yunhai; Chao, Alex; Corbett, Willian; Fox, John et al.
Object Type: Report
System: The UNT Digital Library
IN SITU REMEDIATION OF CONTAMINATED SEDIMENTS - ACTIVE CAPPING TECHNOLOGY (open access)

IN SITU REMEDIATION OF CONTAMINATED SEDIMENTS - ACTIVE CAPPING TECHNOLOGY

Active capping is a relatively new approach for treating contaminated sediments. It involves applying chemically reactive amendments to the sediment surface. The main role of active caps is to stabilize contaminants in contaminated sediments, lower the bioavailable pool of contaminants, and reduce the release of contaminants to the water column. Metals are common contaminants in many marine and fresh water environments as a result of industrial and military activities. The mobile, soluble forms of metals are generally considered toxic. Induced chemical precipitation of these metals can shift toxic metals from the aqueous phase to a solid, precipitated phase which is often less bioavailable. This approach can be achieved through application of sequestering agents such as rock phosphates, organoclays, zeolites, clay minerals, and biopolymers (e.g., chitosan) in active capping technology. Active capping holds great potential for a more permanent solution that avoids residual risks resulting from contaminant migration through the cap or breaching of the cap. In addition to identifying superior active capping agents, research is needed to optimize application techniques, application rates, and amendment combinations that maximize sequestration of contaminants. A selected set of active capping treatment technologies has been demonstrated at a few sites, including a field demonstration at …
Date: September 2, 2010
Creator: Knox, A.; Roberts, J.; Paller, M. & Reible, D.
Object Type: Article
System: The UNT Digital Library
Comments on large-N volume independence (open access)

Comments on large-N volume independence

We study aspects of the large-N volume independence on R{sup 3} X L{sup {Gamma}}, where L{sup {Gamma}} is a {Gamma}site lattice for Yang-Mills theory with adjoint Wilson-fermions. We find the critical number of lattice sites above which the center-symmetry analysis on L{sup {Gamma}} agrees with the one on the continuum S{sup 1}. For Wilson parameter set to one and {Gamma}{>=}2, the two analyses agree. One-loop radiative corrections to Wilson-line masses are finite, reminiscent of the UV-insensitivity of the Higgs mass in deconstruction/Little-Higgs theories. Even for theories with {Gamma}=1, volume independence in QCD(adj) may be guaranteed to work by tuning one low-energy effective field theory parameter. Within the parameter space of the theory, at most three operators of the 3d effective field theory exhibit one-loop UV-sensitivity. This opens the analytical prospect to study 4d non-perturbative physics by using lower dimensional field theories (d=3, in our example).
Date: June 2, 2010
Creator: Poppitz, Erich; U., /Toronto; Unsal, Mithat & /SLAC /Stanford U., Phys. Dept.
Object Type: Article
System: The UNT Digital Library
IDENTIFICATION OF APPROPRIATE QUALIFICATION TESTING AND END-OF-LIFE WASTE STORAGE CONSIDERATIONS FOR DEEP BED SAND FILTERS (open access)

IDENTIFICATION OF APPROPRIATE QUALIFICATION TESTING AND END-OF-LIFE WASTE STORAGE CONSIDERATIONS FOR DEEP BED SAND FILTERS

Deep bed sand (DBS) filters have filtered radioactive particulates at two United States Department of Energy (DOE) sites since 1948. Some early DBS filters experienced issues with chemical attack on support tiles, requiring significant repairs. Designs of DBS filters constructed since 1970 paid greater attention to chemical compatibility, resulting in decades of reliable performance since 1975.
Date: June 2, 2010
Creator: Matthews, K.
Object Type: Article
System: The UNT Digital Library
2009 Wind Technologies Market Report (open access)

2009 Wind Technologies Market Report

This report addresses the U.S. wind power industry during the year of 2009.
Date: August 2, 2010
Creator: Wiser, Ryan & Bolinger, Mark
Object Type: Report
System: The UNT Digital Library
SALTSTONE 1QCY10 TCLP RESULTS (open access)

SALTSTONE 1QCY10 TCLP RESULTS

The Saltstone Production Facility (SPF) receives waste from Tank 50H for treatment. In the first quarter of the 2010 calendar year (1QCY10), Tank 50H accepted transfers of approximately 32 kgal from the Effluent Treatment Project (ETP), approximately 10 kgal from Tank 710 - the H-Canyon General Purpose Evaporator, approximately 32 kgal from the H-Canyon Super Kukla campaign, and approximately 26 kgal from the Modular Caustic Side Solvent Extraction Unit (MCU) Decontaminated Salt Solution Hold Tank (DSS-HT). The Saltstone Grout Sampling plan provides the South Carolina Department of Health and Environmental Control (SCDHEC) with the chemical and physical characterization strategy for the salt solution which is to be disposed of in the Z-Area Solid Waste Landfill (ISWLF). During operation, samples were collected from Tank 50H and grout samples prepared to determine the non-hazardous nature of the grout to meet the requirements of the South Carolina Hazardous Waste Management Regulations (SCHWMR) R.61-79.261.24(b) and R.61-79.268.48(a). Savannah River National Laboratory (SRNL) was asked to prepare saltstone from samples of Tank 50H obtained January 8, 2010 during 1QCY10 to determine the non-hazardous nature of the grout. The samples were cured and shipped to Babcock & Wilcox Technical Services Group-Radioisotope and Analytical Chemistry Laboratory (B&W TSG-RACL) …
Date: June 2, 2010
Creator: Reigel, M.
Object Type: Report
System: The UNT Digital Library
Identification of the Charge Carriers in Cerium Phosphate Ceramics (open access)

Identification of the Charge Carriers in Cerium Phosphate Ceramics

The total conductivity of Sr-doped cerium orthophosphate changes by nearly two orders of magnitude depending on the oxygen and hydrogen content of the atmosphere. The defect model for the system suggests that this is because the identity of the dominant charge carrier can change from electron holes to protons when the sample is in equilibrium with air vs. humidified hydrogen. In this work are presented some preliminary measurements that can help to clarify this exchange between carriers. The conduction behavior of a 2percent Sr-doped CePO4 sample under symmetric atmospheric conditions is investigated using several techniques, including AC impedance, H/D isotope effects, and chronoamperometry.
Date: June 2, 2010
Creator: Ray, Hannah L. & Jonghe, Lutgard C. De
Object Type: Article
System: The UNT Digital Library
Transition in Electron Transport in a Cylindrical Hall Thruster (open access)

Transition in Electron Transport in a Cylindrical Hall Thruster

Through the use of high-speed camera and Langmuir probe measurements in a cylindrical Hall thruster, we report the discovery of a rotating spoke of increased plasma density and light emission which correlates with increased electron transport across the magnetic field. As cathode electron emission is increased, a sharp transition occurs where the spoke disappears and electron transport decreases. This suggests that a significant fraction of the electron current might be directed through the spoke.
Date: June 2, 2010
Creator: Parker, J. B.; Raitses, Y. & Fisch, N. J.
Object Type: Report
System: The UNT Digital Library
Nanoscale Electronic Inhomogeneity in In_2Se_3 Nanoribbons Revealed by Microwave Impedance Microscopy (open access)

Nanoscale Electronic Inhomogeneity in In_2Se_3 Nanoribbons Revealed by Microwave Impedance Microscopy

Driven by interactions due to the charge, spin, orbital, and lattice degrees of freedom, nanoscale inhomogeneity has emerged as a new theme for materials with novel properties near multiphase boundaries. As vividly demonstrated in complex metal oxides and chalcogenides, these microscopic phases are of great scientific and technological importance for research in hightemperature superconductors, colossal magnetoresistance effect, phase-change memories, and domain switching operations. Direct imaging on dielectric properties of these local phases,however, presents a big challenge for existing scanning probe techniques. Here, we report the observation of electronic inhomogeneity in indium selenide (In{sub 2}Se{sub 3}) nanoribbons by near-field scanning microwave impedance microscopy. Multiple phases with local resistivity spanning six orders of magnitude are identified as the coexistence of superlattice, simple hexagonal lattice and amorphous structures with {approx}100nm inhomogeneous length scale, consistent with high-resolution transmission electron microscope studies. The atomic-force-microscope-compatible microwave probe is able to perform quantitative sub-surface electronic study in a noninvasive manner. Finally, the phase change memory function in In{sub 2}Se{sub 3} nanoribbon devices can be locally recorded with big signal of opposite signs.
Date: June 2, 2010
Creator: Lai, K.J.
Object Type: Article
System: The UNT Digital Library
Theory of Fano Resonances in Graphene: The Kondo effect probed by STM (open access)

Theory of Fano Resonances in Graphene: The Kondo effect probed by STM

We consider the theory of Kondo effect and Fano factor energy dependence for magnetic impurity (Co) on graphene. We have performed a first principles calculation and find that the two dimensional E{sub 1} representation made of d{sub xz}, d{sub yz} orbitals is likely to be responsible for the hybridization and ultimately Kondo screening for cobalt on graphene. There are few high symmetry sites where magnetic impurity atom can be adsorbed. For the case of Co atom in the middle of hexagon of carbon lattice we find anomalously large Fano q-factor, q {approx} 80 and strongly suppressed coupling to conduction band. This anomaly is a striking example of quantum mechanical interference related to the Berry phase inherent to graphene band structure.
Date: June 2, 2010
Creator: Wehling, T.O.
Object Type: Article
System: The UNT Digital Library
Beam-energy and laser beam-profile monitor at the BNL LINAC (open access)

Beam-energy and laser beam-profile monitor at the BNL LINAC

We are developing a non-interceptive beam profile and energy monitor for H{sup -} beams in the high energy beam transport (HEBT) line at the Brookhaven National Lab linac. Electrons that are removed from the beam ions either by laser photodetachment or stripping by background gas are deflected into a Faraday cup. The beam profile is measured by stepping a narrow laser beam across the ion beam and measuring the electron charge vs. transverse laser position. There is a grid in front of the collector that can be biased up to 125kV. The beam energy spectrum is determined by measuring the electron charge vs. grid voltage. Beam electrons have the same velocity as the beam and so have an energy of 1/1836 of the beam protons. A 200MeV H{sup -} beam yields 109keV electrons. Energy measurements can be made with either laser-stripped or gas-stripped electrons.
Date: May 2, 2010
Creator: Connolly, R.; Briscoe, B.; Degen, C.; DeSanto, L.; Meng, W.; Minty, M. et al.
Object Type: Article
System: The UNT Digital Library
Visualization of Charge Distribution in a Lithium Battery Electrode (open access)

Visualization of Charge Distribution in a Lithium Battery Electrode

We describe a method for direct determination and visualization of the distribution of charge in a composite electrode. Using synchrotron X-ray microdiffraction, state-of-charge profiles in-plane and normal to the current collector were measured. In electrodes charged at high rate, the signatures of nonuniform current distribution were evident. The portion of a prismatic cell electrode closest to the current collector tab had the highest state of charge due to electronic resistance in the composite electrode and supporting foil. In a coin cell electrode, the active material at the electrode surface was more fully charged than that close to the current collector because the limiting factor in this case is ion conduction in the electrolyte contained within the porous electrode.
Date: July 2, 2010
Creator: Liu, Jun; Kunz, Martin; Chen, Kai; Tamura, Nobumichi & Richardson, Thomas J.
Object Type: Article
System: The UNT Digital Library
Probing Reaction Dynamics of Transition-Metal Complexes in Solution via Time-Resolved Soft X-ray Spectroscopy (open access)

Probing Reaction Dynamics of Transition-Metal Complexes in Solution via Time-Resolved Soft X-ray Spectroscopy

We report the first time-resolved soft x-ray measurements of solvated transition-metal complexes. L-edge spectroscopy directly probes dynamic changes in ligand-field splitting of 3d orbitals associated with the spin transition, and mediated by changes in ligand-bonding.
Date: May 2, 2010
Creator: Huse, Nils; Kim, Tae Kyu; Khalil, Munira; Jamula, Lindsey; McCusker, James K. & Schoenlein, Robert W.
Object Type: Article
System: The UNT Digital Library
Constraints on the flux of Ultra-High Energy neutrinos from WSRT observations (open access)

Constraints on the flux of Ultra-High Energy neutrinos from WSRT observations

Context. Ultra-high energy (UHE) neutrinos and cosmic rays initiate particle cascades underneath theMoon?s surface. These cascades have a negative charge excess and radiate Cherenkov radio emission in a process known as the Askaryan effect. The optimal frequencywindow for observation of these pulses with radio telescopes on the Earth is around 150 MHz. Aims. By observing the Moon with the Westerbork Synthesis Radio Telescope array we are able to set a new limit on the UHEneutrino flux. Methods. The PuMa II backend is used to monitor the Moon in 4 frequency bands between 113 and 175 MHz with a samplingfrequency of 40 MHz. The narrowband radio interference is digitally filtered out and the dispersive effect of the Earth?s ionosphere is compensated for. A trigger system is implemented to search for short pulses. By inserting simulated pulses in the raw data, thedetection efficiency for pulses of various strength is calculated. Results. With 47.6 hours of observation time, we are able to set a limit onthe UHE neutrino flux. This new limit is an order of magnitude lower than existing limits. In the near future, the digital radio array LOFAR will be used to achieve an even lower limit.
Date: April 2, 2010
Creator: Scholten, O.; Bacelar, J.; Braun, R.; de Bruyn, A.G.; Falcke, H.; Singh, K. et al.
Object Type: Article
System: The UNT Digital Library
Investigating two-photon double ionization of D2 by XUV-Pump -- XUV-Probe experiments at FLASH (open access)

Investigating two-photon double ionization of D2 by XUV-Pump -- XUV-Probe experiments at FLASH

Using a novel split-mirror set-up attached to a Reaction Microscope at the Free electron LASer in Hamburg (FLASH) we demonstrate an XUV-pump -- XUV-probe ((hbar omega = 38 eV) experiment by tracing the ultra-fast nuclear wave-packet motion in the D2+ (1s sigma g-state) with<10 fs time resolution. Comparison with time-dependent calculations yields excellent agreement with the measured vibrational period of 22+-4 fs in D2+, points to the importance of the inter-nuclear distance dependent ionization probability and paves the way to control sequential and non-sequential two-photon double ionization contributions.
Date: August 2, 2010
Creator: Collaboration, FLASH; Jiang, Y.; Rudenko, A.; Perez-Torres, J.; Foucar, L.; Kurka, M. et al.
Object Type: Article
System: The UNT Digital Library