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Test Results of the first 3.7 m Long Nb3Sn Quadrupole by LARP and Future Plans
In December 2009 during its first cold test, LQS01, the first long Nb{sub 3}Sn Quadrupole made by LARP (LHC Accelerator Research Program, a collaboration of BNL, FNAL, LBNL and SLAC), reached its target field gradient of 200 T/m. This target was set in 2005 by the US Department fo Energy, CERN and LARP, as a significant milestone toward the development of Nb{sub 3}Sn quadrupoles for possible use in LHC luminosity upgrades. LQS01 is a 90 mm aperture, 3.7 m long quadrupole using Nb{sub 3}Sn coils. The coil layout is equal to the layout used in the LARP Technological Quadrupoles (TQC and TQS models). Pre-stress and support are provided by a segmented aluminum shell pre-loaded using bladders and keys, similarly to the TQS models. After the first test the magnet was disassembled, reassembled with an optimized pre-stress, and reached 222 T/m at 4.5 K. In this paper we present the results of both tests and the next steps of the Long Quadrupole R&D.
Date:
August 1, 2010
Creator:
Ambrosio, G.; Andreev, N.; Anerella, M.; Barzi, E.; Bingham, B.; Bocian, D. et al.
Object Type:
Article
System:
The UNT Digital Library
Design and Implementation of a Metadata-rich File System
Despite continual improvements in the performance and reliability of large scale file systems, the management of user-defined file system metadata has changed little in the past decade. The mismatch between the size and complexity of large scale data stores and their ability to organize and query their metadata has led to a de facto standard in which raw data is stored in traditional file systems, while related, application-specific metadata is stored in relational databases. This separation of data and semantic metadata requires considerable effort to maintain consistency and can result in complex, slow, and inflexible system operation. To address these problems, we have developed the Quasar File System (QFS), a metadata-rich file system in which files, user-defined attributes, and file relationships are all first class objects. In contrast to hierarchical file systems and relational databases, QFS defines a graph data model composed of files and their relationships. QFS incorporates Quasar, an XPATH-extended query language for searching the file system. Results from our QFS prototype show the effectiveness of this approach. Compared to the de facto standard, the QFS prototype shows superior ingest performance and comparable query performance on user metadata-intensive operations and superior performance on normal file metadata operations.
Date:
January 19, 2010
Creator:
Ames, S; Gokhale, M B & Maltzahn, C
Object Type:
Report
System:
The UNT Digital Library
QMDS: A File System Metadata Management Service Supporting a Graph Data Model-Based Query Language
Proposes QMDS: a file system metadata management service that integrates all file system metadata and uses a graph model with attributes on nodes and edges.
Date:
September 13, 2010
Creator:
Ames, S; Gokhale, M B & Maltzahn, C
Object Type:
Article
System:
The UNT Digital Library
Abiotic Degradation Rates for Carbon Tetrachloride and Chloroform: Progress in FY 2010
This report documents the progress made through FY 2010 on a project initiated in FY 2006 to help address uncertainties related to the rates of hydrolysis in groundwater at the Hanford Site for carbon tetrachloride (CT) and chloroform (CF). The study also explores the possible effects of contact with minerals and sediment (i.e., heterogeneous hydrolysis) on these rates. The research was initiated to decrease the uncertainties in abiotic degradation rates of CT and chloroform CF associated with temperature and possible heterogeneous effects. After 2 years of data collection, the first evidence for heterogeneous effects was identified for hydrolysis of CT, and preliminary evidence for the effects of different mineral types on CF hydrolysis rates also was reported. The CT data showed no difference among mineral types, whereas significant differences were seen in the CF results, perhaps due to the fact that CF hydrolyzes by both neutral and base-catalyzed mechanisms whereas CT follows only the neutral hydrolysis path. In this report, we review the project objectives, organization, and technical approaches taken, update the status and results of the hydrolysis-rate experiments after 4 years of experimentation (i.e., through FY 2010), and provide a brief discussion of how these results add to scientific …
Date:
December 8, 2010
Creator:
Amonette, James E.; Jeffers, Peter M.; Qafoku, Odeta; Russell, Colleen K.; Humphrys, Daniel R.; Wietsma, Thomas W. et al.
Object Type:
Report
System:
The UNT Digital Library
Abiotic Degradation Rates for Carbon Tetrachloride and Chloroform: Progress in FY2009
This report documents the progress made through FY 2009 on a project initiated in FY 2006 to help address uncertainties related to the rates of hydrolysis in groundwater for carbon tetrachloride (CT) and chloroform (CF). The study seeks also to explore the possible effects of contact with minerals and sediment (i.e., heterogeneous hydrolysis) on these rates. In previous years the work was funded as two separate projects by various sponsors, all of whom received their funding from the U.S. Department of Energy (DOE). In FY2009, the projects were combined and funded by CH2MHill Plateau Remediation Corporation (CHPRC). Work in FY2009 was performed by staff at the Pacific Northwest National Laboratory (PNNL). Staff from the State University of New York at Cortland (SUNY–Cortland) contributed in previous years.
Date:
March 2010
Creator:
Amonette, James E.; Jeffers, Peter M.; Qafoku, Odeta; Russell, Colleen K.; Wietsma, Thomas W. & Truex, Michael J.
Object Type:
Report
System:
The UNT Digital Library
ARPES studies of the electronic structure of LaOFe(P,As)
We report a comparison study of LaOFeP and LaOFeAs, two parent compounds of recently discovered iron-pnictide superconductors, using angle-resolved photoemission spectroscopy. Both systems exhibit some common features that are very different from well-studied cuprates. In addition, important differences have also been observed between these two ferrooxypnictides. For LaOFeP, quantitative agreement can be found between our photoemission data and the LDA band structure calculations, suggesting that a weak coupling approach based on an itinerant ground state may be more appropriate for understanding this new superconducting compound. In contrast, the agreement between LDA calculations and experiments in LaOFeAs is relatively poor, as highlighted by the unexpected Fermi surface topology around ({pi},{pi}). Further investigations are required for a comprehensive understanding of the electronic structure of LaOFeAs and related compounds.
Date:
June 2, 2010
Creator:
Analytis, J.G.
Object Type:
Article
System:
The UNT Digital Library
Fermi surface of SrFe2P2 determined by de Haas-van Alphen effect
We report measurements of the Fermi surface (FS) of the ternary iron-phosphide SrFe{sub 2}P{sub 2} using the de Haas-van Alphen effect. The calculated FS of this compound is very similar to SrFe{sub 2}As{sub 2}, the parent compound of the high temperature superconductors. Our data show that the Fermi surface is composed of two electron and two hole sheets in agreement with bandstructure calculations. Several of the sheets show strong c-axis warping emphasizing the importance of three-dimensionality in the non-magnetic state of the ternary pnictides. We find that the electron and hole pockets have a different topology, implying that this material does not satisfy a ({pi},{pi}) nesting condition.
Date:
May 26, 2010
Creator:
Analytis, J.G.
Object Type:
Article
System:
The UNT Digital Library
Quantum Oscillations in the Parent pnictide BaFe2As2 : Itinerant Electrons in the Reconstructed State
We report quantum oscillation measurements that enable the direct observation of the Fermi surface of the low temperature ground state of BaFe{sub 2}As{sub 2}. From these measurements we characterize the low energy excitations, revealing that the Fermi surface is reconstructed in the antiferromagnetic state, but leaving itinerant electrons in its wake. The present measurements are consistent with a conventional band folding picture of the antiferromagnetic ground state, placing important limits on the topology and size of the Fermi surface.
Date:
May 26, 2010
Creator:
Analytis, J.G.
Object Type:
Article
System:
The UNT Digital Library
Bulk Superconductivity and Disorder in Single Crystals of LaFePO
We have studied the intrinsic normal and superconducting properties of the oxypnictide LaFePO. These samples exhibit bulk superconductivity and the evidence suggests that stoichiometric LaFePO is indeed superconducting, in contrast to other reports. We find that superconductivity is independent of the interplane residual resistivity {rho}{sub 0} and discuss the implications of this on the nature of the superconducting order parameter. Finally we find that, unlike T{sub c}, other properties in single-crystal LaFePO including the resistivity and magnetoresistance, can be very sensitive to disorder.
Date:
February 15, 2010
Creator:
Analytis, James G.; Chu, Jiun-Haw; Erickson, Ann S.; Kucharczyk, Chris; /Stanford U., Appl. Phys. Dept.; Serafin, Alessandro et al.
Object Type:
Article
System:
The UNT Digital Library
A search for $ZH\rightarrow \mu\mu b \bar{b}$ production at the Tevatron
The Standard Model describes with a very good accuracy all interactions of the, so far, known elementary particles. However the Higgs mechanism, which gives rise to the observed mass of these particles, has not yet been confirmed. The Higgs particle has not yet been observed, and the observation or exclusion is an important test of the Standard Model. The Standard Model does not predict the mass of the Higgs particle, however it does impose some limits on the range in which this mass can lie. In direct searches a Higgs with a mass smaller than 114.4 GeV and within 162 GeV and 166 GeV has been excluded at 95% CL at the LEP and the Tevatron colliders. The analysis presented in this thesis is aimed to search for the ZH → μμb$\bar{b}$ events in 3.1 fb<sup>-1</sup> of data collected with the DØ detector in p$\bar{p}$ collisions at √s = 1.96 TeV.
Date:
April 20, 2010
Creator:
Ancu, Lucian-Stefan
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Chemistry, phase formation, and catalytic activity of thin palladium-containing oxide films synthesized by plasma-assisted physical vapor deposition
The chemistry, microstructure, and catalytic activity of thin films incorporating palladium were studied using scanning and transmission electron microscopies, X-ray diffraction, spectrophotometry, 4-point probe and catalytic tests. The films were synthesized using pulsed filtered cathodic arc and magnetron sputter deposition, i.e. techniques far from thermodynamic equilibrium. Catalytic particles were formed by thermally cycling thin films of the Pd-Pt-O system. The evolution and phase formation in such films as a function of temperature were discussed in terms of the stability of PdO and PtO2 in air. The catalytic efficiency was found to be strongly affected by the chemical composition, with oxidized palladium definitely playing a major role in the combustion of methane. Reactive sputter deposition of thin films in the Pd-Zr-Y-O system allowed us forming microstructures ranging from nanocrystalline zirconia to palladium nanoparticles embedded in a (Zr,Y)4Pd2O matrix. The sequence of phase formation is put in relation to simple thermodynamic considerations.
Date:
November 26, 2010
Creator:
Anders, Andre
Object Type:
Article
System:
The UNT Digital Library
Discharge Physics of High Power Impulse Magnetron Sputtering
High power impulse magnetron sputtering (HIPIMS) is pulsed sputtering where the peak power exceeds the time-averaged power by typically two orders of magnitude. The peak power density, averaged over the target area, can reach or exceed 107 W/m2, leading to plasma conditions that make ionization of the sputtered atoms very likely. A brief review of HIPIMS operation is given in a tutorial manner, illustrated by some original data related to the self-sputtering of niobium in argon and krypton. Emphasis is put on the current-voltage-time relationships near the threshold of self-sputtering runaway. The great variety of current pulse shapes delivers clues on the very strong gas rarefaction, self-sputtering runaway conditions, and the stopping of runaway due to the evolution of atom ionization and ion return probabilities as the gas plasma is replaced by metal plasma. The discussions are completed by considering instabilities and the special case of ?gasless? self-sputtering.
Date:
October 13, 2010
Creator:
Anders, Andre
Object Type:
Article
System:
The UNT Digital Library
A Plasma Lens for Magnetron Sputtering
A plasma lens, consisting of a solenoid and potential-defining ring electrodes, has been placed between a magnetron and substrates to be coated. Photography reveals qualitative information on excitation, ionization, and the transport of plasma to the substrate.
Date:
November 30, 2010
Creator:
Anders, Andre & Brown, Jeff
Object Type:
Article
System:
The UNT Digital Library
Dense Metal Plasma in a Solenoid for Ion Beam Neutralization
Space-charge neutralization is required to compress and focus a pulsed, high-current ion beam on a target for warm dense matter physics or heavy ion fusion experiments. We described approaches to produce dense plasma in and near the final focusing solenoid through which the ion beam travels, thereby providing an opportunity for the beam to acquire the necessary space-charge compensating electrons. Among the options are plasma injection from pulsed vacuum arc sources located outside the solenoid, and using a high current (> 4 kA) pulsed vacuum arc plasma from a ring cathode near the edge of the solenoid. The plasma distribution is characterized by photographic means, by an array of movable Langmuir probes, by a small single probe, and by evaluating Stark broadening of the Balmer H beta spectral line. In the main approach described here, the plasma is produced at several cathode spots distributed azimuthally on the ring cathode. It is shown that the plasma is essentially hollow, as determined by the structure of the magnetic field, though the plasma density exceeds 1014 cm-3 in practically all zones of the solenoid volume if the ring electrode is placed a few centimeters off the center of the solenoid. The plasma is …
Date:
October 30, 2010
Creator:
Anders, Andre; Kauffeldt, Marina; Oks, Efim M. & Roy, Prabir K.
Object Type:
Article
System:
The UNT Digital Library
Hollow Plasma in a Solenoid
A ring cathode for a pulsed, high-current, multi-spot cathodic arc discharge was placed inside a pulsed magnetic solenoid. Photography is used to evaluate the plasma distribution. The plasma appears hollow for cathode positions close the center of the solenoid, and it is guided closer to the axis when the cathode is away from the center.
Date:
November 30, 2010
Creator:
Anders, Andre; Kauffeldt, Marina; Oks, Efim M. & Roy, Prabir K.
Object Type:
Article
System:
The UNT Digital Library
A Seemingly Simple Task: Filling a Solenoid Volume in Vacuum with Dense Plasma
Space-charge neutralization of a pulsed, high-current ion beam is required to compress and focus the beam on a target for warm dense matter physics or heavy ion fusion experiments. We described attempts to produce dense plasma in and near the final focusing solenoid through which the ion beam travels, thereby providing an opportunity for the beam to acquire the necessary charge-compensating electrons. Among the options are plasma injection from four pulsed vacuum arc sources located outside the solenoid, and using a high current (> 4 kA) pulsed vacuum arc plasma from a ring cathode near the edge of the solenoid. The plasma distribution is characterized by photographic means and by an array of movable Langmuir probes. The plasma is produced at several cathode spots distributed azimuthally on the ring cathode. Beam neutralization and compression are accomplished, though issues of density, uniformity, and pulse-to-pulse reproducibly remain to be solved.
Date:
June 24, 2010
Creator:
Anders, Andre; Kauffeldt, Marina; Roy, Prabir & Oks, Efim
Object Type:
Article
System:
The UNT Digital Library
Assistance to States on Electric Industry Issues
This project seeks to educate state policymakers through a coordinated approach involving state legislatures, regulators, energy officials, and governors’ staffs. NCSL’s activities in this project focus on educating state legislators. Major components of this proposal include technical assistance to state legislatures, briefing papers, coordination with the National Council on Electricity Policy, information assistance, coordination and outreach, meetings, and a set of transmission-related activities.
Date:
October 25, 2010
Creator:
Andersen, Glen
Object Type:
Report
System:
The UNT Digital Library
Low-speckle holographic beam shaping of high-coherence EUV sources
This paper describes a method to arbitrarily shape and homogenize high-coherence extreme ultraviolet sources using time-varying holographic optical elements and a scanning subsystem to mitigate speckle. In systems with integration times longer than 100 ms, a speckle contrast below 1% can be achieved.
Date:
August 1, 2010
Creator:
Anderson, Christopher N.; Miyakawa, Ryan H. & Naulleau, Patrick
Object Type:
Article
System:
The UNT Digital Library
Measurement of muon neutrino and antineutrino induced single neutral pion production cross sections
Elucidating the nature of neutrino oscillation continues to be a goal in the vanguard of the efforts of physics experiment. As neutrino oscillation searches seek an increasingly elusive signal, a thorough understanding of the possible backgrounds becomes ever more important. Measurements of neutrino-nucleus interaction cross sections are key to this understanding. Searches for {nu}{sub {mu}} {yields} {nu}{sub e} oscillation - a channel that may yield insight into the vanishingly small mixing parameter {theta}{sub 13}, CP violation, and the neutrino mass hierarchy - are particularly susceptible to contamination from neutral current single {pi}{sup 0} (NC 1{pi}{sup 0}) production. Unfortunately, the available data concerning NC 1{pi}{sup 0} production are limited in scope and statistics. Without satisfactory constraints, theoretical models of NC 1{pi}{sup 0} production yield substantially differing predictions in the critical E{sub {nu}} {approx} 1 GeV regime. Additional investigation of this interaction can ameliorate the current deficiencies. The Mini Booster Neutrino Experiment (MiniBooNE) is a short-baseline neutrino oscillation search operating at the Fermi National Accelerator Laboratory (Fermilab). While the oscillation search is the principal charge of the MiniBooNE collaboration, the extensive data ({approx} 10{sup 6} neutrino events) offer a rich resource with which to conduct neutrino cross section measurements. This work concerns …
Date:
December 1, 2010
Creator:
Anderson, Colin & U., /Yale
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
DOE Webinar - Residential Geothermal Heat Pump Retrofits
This presentation was given December 14, 2010, as part of DOE's Webinar series. The presentation discusses geothermal heat pump retrofits, technology options, and an overview of geothermal energy and geothermal heat pumps.
Date:
December 14, 2010
Creator:
Anderson, E. R.
Object Type:
Presentation
System:
The UNT Digital Library
NREL GHP [Geothermal Heat Pump] Showcase: GHP Installation and Intensive in situ and Performance Monitoring at NREL's Solar Radiation and Research Laboratory; Preprint
This document provides an overview of the geothermal heat pump (GHP) showcase at NREL and how it will help the SRRL site move forward with the goal of being a model of sustainability within the NREL campus, providing an effective demonstration of GHP systems and needed space conditioning for laboratory expansion.
Date:
July 1, 2010
Creator:
Anderson, E. R.
Object Type:
Article
System:
The UNT Digital Library
The prediction of Neutron Elastic Scattering from Tritium for E(n) = 6-14 MeV
In a recent report Navratil et al. evaluated the angle-integrated cross section and the angular distribution for 14-MeV n+T elastic scattering by inferring these cross sections from accurately measured p+3He angular distributions. This evaluation used a combination of two theoretical treatments, based on the no-core shell model and resonating-group method (NCSM/RGM) and on the R-matrix formalism, to connect the two charge-symmetric reactions n+T and p+{sup 3}He. In this report we extend this treatment to cover the neutron incident energy range 6-14 MeV. To do this, we evaluate angle-dependent correction factors for the NCSM/RGM calculations so that they agree with the p+{sup 3}He data near 6 MeV, and using the results found earlier near 14 MeV we interpolate these correction factors to obtain correction factors throughout the 6-14 MeV energy range. The agreement between the corrected NCSM/RGM and R-Matrix values for the integral elastic cross sections is excellent ({+-}1%), and these are in very good agreement with total cross section experiments. This result can be attributed to the nearly constant correction factors at forward angles, and to the evidently satisfactory physics content of the two calculations. The difference in angular shape, obtained by comparing values of the scattering probability distribution P({mu}) …
Date:
June 14, 2010
Creator:
Anderson, J. D.; Dietrich, F. S.; Luu, T.; McNabb, D. P.; Navratil, P. & Quaglioni, S.
Object Type:
Report
System:
The UNT Digital Library
Paleoclimatic implications of glacial and postglacial refugia for Pinus pumila in western Beringia
Palynological results from Julietta Lake currently provide the most direct evidence to support the existence of a glacial refugium for Pinus pumila in mountains of southwestern Beringia. Both percentages and accumulation rates indicate the evergreen shrub survived until at least {approx}19,000 14C yr B.P. in the Upper Kolyma region. Percentage data suggest numbers dwindled into the late glaciation, whereas pollen accumulation rates point towards a more rapid demise shortly after {approx}19,000 14C yr B.P. Pinus pumila did not re-establish in any great numbers until {approx}8100 14C yr B.P., despite the local presence {approx}9800 14C yr B.P. of Larix dahurica, which shares similar summer temperature requirements. The postglacial thermal maximum (in Beringia {approx}11,000-9000 14C yr B.P.) provided Pinus pumila shrubs with equally harsh albeit different conditions for survival than those present during the LGM. Regional records indicate that in this time of maximum warmth Pinus pumila likely sheltered in a second, lower-elevation refugium. Paleoclimatic models and modern ecology suggest that shifts in the nature of seasonal transitions and not only seasonal extremes have played important roles in the history of Pinus pumila over the last {approx}21,000 14C yr B.P.
Date:
February 5, 2010
Creator:
Anderson, P M; Lozhkin, A V; Solomatkina, T B & Brown, T A
Object Type:
Article
System:
The UNT Digital Library
Environmental Risk Evaluation System (ERES) for Offshore Wind - Mock-Up of ERES, Fiscal Year 2010 Progress Report
The Environmental Risk Evaluation System (ERES) has been created to set priorities among the environmental risks from offshore wind development. This report follows the conceptual design for ERES and shows what the system would look like, using a web interface created as part of a Knowledge Management System (KMS) for offshore wind. The KMS, called Zephyrus, and ERES for offshore wind, will be populated and made operational in a later phase of the project.
Date:
November 1, 2010
Creator:
Anderson, Richard M.; Copping, Andrea E. & Van Cleve, Frances B.
Object Type:
Report
System:
The UNT Digital Library