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Discovery of Pulsations from the Pulsar J0205 6449 in SNR 3C 58 with the Fermi Gamma-Ray Space Telescope
We report the discovery of {gamma}-ray pulsations ({ge}0.1 GeV) from the young radio and X-ray pulsar PSR J0205 + 6449 located in the Galactic supernova remnant 3C 58. Data in the {gamma}-ray band were acquired by the Large Area Telescope aboard the Fermi Gamma-ray Space Telescope (formerly GLAST), while the radio rotational ephemeris used to fold {gamma}-rays was obtained using both the Green Bank Telescope and the Lovell telescope at Jodrell Bank. The light curve consists of two peaks separated by 0.49 {+-} 0.01 {+-} 0.01 cycles which are aligned with the X-ray peaks. The first {gamma}-ray peak trails the radio pulse by 0.08 {+-} 0.01 {+-} 0.01, while its amplitude decreases with increasing energy as for the other {gamma}-ray pulsars. Spectral analysis of the pulsed {gamma}-ray emission suggests a simple power law of index -2.1 {+-} 0.1 {+-} 0.2 with an exponential cutoff at 3.0{sub -0.7}{sup +1.1} {+-} 0.4 GeV. The first uncertainty is statistical and the second is systematic. The integral {gamma}-ray photon flux above 0.1 GeV is (13.7 {+-} 1.4 {+-} 3.0) x 10{sup -8} cm{sup -2} s{sup -1}, which implies for a distance of 3.2 kpc and assuming a broad fan-like beam a luminosity of 8.3 …
Date:
December 1, 2011
Creator:
Abdo, Aous A.; Ackermann, M.; Ajello, Marco; Atwood, William B.; Axelsson, M.; Baldini, L. et al.
Object Type:
Article
System:
The UNT Digital Library
Application of Quadrature Methods for Re-Weighting in Lattice QCD
Re-weighting is a useful tool that has been employed in Lattice QCD in different contexts including, tuning the strange quark mass, approaching the light quark mass regime, and simulating electromagnetic fields on top of QCD gauge configurations. In case of re-weighting the sea quark mass, the re-weighting factor is given by the ratio of the determinants of two Dirac operators D{sub a} and D{sub b}. A popular approach for computing this ratio is to use a pseudofermion representation of the determinant of the composite operator {Omega} = D{sub a}(D{sub b}{sup {dagger}}D{sub b}){sup -1} D{sub a}{sup {dagger}}. Here, we study using quadrature methods together with noise vectors to compute the ratio of determinants. We show that, with quadrature methods each determinant can be computed separately using the operators {Omega}{sub a} = D{sub a}{sup {dagger}}D{sub a} and {Omega}{sub b} = D{sub b}{sup {dagger}} D{sub b}. We also discuss using bootstrap re-sampling to remove the bias from the determinant estimator.
Date:
December 1, 2011
Creator:
Abdou Abdel-Rehim, William Detmold, Kostas Orginos
Object Type:
Article
System:
The UNT Digital Library
TECHNETIUM RETENTION IN WTP LAW GLASS WITH RECYCLE FLOW-SHEET DM10 MELTER TESTING VSL-12R2640-1 REV 0
Melter tests were conducted to determine the retention of technetium and other volatiles in glass while processing simulated Low Activity Waste (LAW) streams through a DM10 melter equipped with a prototypical off-gas system that concentrates and recycles fluid effiuents back to the melter feed. To support these tests, an existing DM10 system installed at Vitreous State Laboratory (VSL) was modified to add the required recycle loop. Based on the Hanford Tank Waste Treatment and Immobilization Plant (WTP) LAW off-gas system design, suitably scaled versions of the Submerged Bed Scrubber (SBS), Wet Electrostatic Precipitator (WESP), and TLP vacuum evaporator were designed, built, and installed into the DM10 system. Process modeling was used to support this design effort and to ensure that issues associated with the short half life of the {sup 99m}Tc radioisotope that was used in this work were properly addressed and that the system would be capable of meeting the test objectives. In particular, this required that the overall time constant for the system was sufficiently short that a reasonable approach to steady state could be achieved before the {sup 99m}Tc activity dropped below the analytical limits of detection. The conceptual design, detailed design, flow sheet development, process model …
Date:
December 11, 2012
Creator:
Abramowitz, Howard; Brandys, Marek; Cecil, Richard; D' Angelo, Nicholas; Matlack, Keith S. et al.
Object Type:
Report
System:
The UNT Digital Library
2013 Inorganic Reaction Mechanisms Gordon Research Conference (March 3-8, 2013 - Hotel Galvez, Galveston TX)
The 2013 Gordon Conference on Inorganic Reaction Mechanisms will present cutting-edge research on the molecular aspects of inorganic reactions involving elements from throughout the periodic table and state-of-the art techniques that are used in the elucidation of reaction mechanisms. The Conference will feature a wide range of topics, such as homogeneous and heterogeneous catalysis, metallobiochemistry, electron-transfer in energy reactions, polymerization, nitrogen fixation, green chemistry, oxidation, solar conversion, alkane functionalization, organotransition metal chemistry, and computational chemistry. The talks will cover themes of current interest including energy, materials, and bioinorganic chemistry. Sections cover: Electron-Transfer in Energy Reactions; Catalytic Polymerization and Oxidation Chemistry; Kinetics and Spectroscopy of Heterogeneous Catalysts; Metal-Organic Chemistry and its Application in Synthesis; Green Energy Conversion;Organometallic Chemistry and Activation of Small Molecules; Advances in Kinetics Modeling and Green Chemistry; Metals in Biology and Disease; Frontiers in Catalytic Bond Activation and Cleavage.
Date:
December 8, 2012
Creator:
Abu-Omar, Mahdi M.
Object Type:
Article
System:
The UNT Digital Library
Hydrogen Safety Training for Researchers and Technical Personnel
None
Date:
December 2, 2011
Creator:
Aceves, S. M.; Espinosa-Loza, F.; Petitpas, G.; Ross, T. O. & Switzer, V. A.
Object Type:
Article
System:
The UNT Digital Library
IEA Wind Task 24 Integration of Wind and Hydropower Systems; Volume 1: Issues, Impacts, and Economics of Wind and Hydropower Integration
This report describes the background, concepts, issues and conclusions related to the feasibility of integrating wind and hydropower, as investigated by the members of IEA Wind Task 24. It is the result of a four-year effort involving seven IEA member countries and thirteen participating organizations. The companion report, Volume 2, describes in detail the study methodologies and participant case studies, and exists as a reference for this report.
Date:
December 1, 2011
Creator:
Acker, T.
Object Type:
Report
System:
The UNT Digital Library
IEA Wind Task 24 Integration of Wind and Hydropower Systems; Volume 2: Participant Case Studies
This report describes the background, concepts, issues and conclusions related to the feasibility of integrating wind and hydropower, as investigated by the members of IEA Wind Task 24. It is the result of a four-year effort involving seven IEA member countries and thirteen participating organizations. The companion report, Volume 2, describes in detail the study methodologies and participant case studies, and exists as a reference for this report.
Date:
December 1, 2011
Creator:
Acker, T.
Object Type:
Report
System:
The UNT Digital Library
Status of EXO-200
EXO-200 is the first phase of the Enriched Xenon Observatory (EXO) experiment, which searches for neutrinoless double beta decay in {sup 136}Xe to measure the mass and probe the Majorana nature of the neutrino. EXO-200 consists of 200 kg of liquid Xe enriched to 80% in {sup 136}Xe in an ultra-low background TPC. Energy resolution is enhanced through the simultaneous collection of scintillation light using Large Area Avalanche Photodiodes (LAAPD's) and ionization charge. It is being installed at the WIPP site in New Mexico, which provides a 2000 meter water-equivalent overburden. EXO-200 will begin taking data in 2009, with the expected two-year sensitivity to the half-life for neutrinoless double beta decay of 6.4 x 10{sup 25} years. According to the most recent nuclear matrix element calculations, this corresponds to an effective Majorana neutrino mass of 0.13 to 0.19 eV. It will also measure the two neutrino mode for the first time in {sup 136}Xe.
Date:
December 6, 2011
Creator:
Ackerman, Nicole
Object Type:
Article
System:
The UNT Digital Library
Constraints on Dark Matter Annihilation in Clusters of Galaxies with the Fermi Large Area Telescope
None
Date:
December 14, 2012
Creator:
Ackermann, M.; Ajello, M.; Allafort, A.; Baldini, L.; Ballet, J.; Barbiellini, G. et al.
Object Type:
Article
System:
The UNT Digital Library
Renaissance of the ~ 1-TeV Fixed-Target Program
This document describes the physics potential of a new fixed-target program based on a {approx}1 TeV proton source. Two proton sources are potentially available in the future: the existing Tevatron at Fermilab, which can provide 800 GeV protons for fixed-target physics, and a possible upgrade to the SPS at CERN, called SPS+, which would produce 1 TeV protons on target. In this paper we use an example Tevatron fixed-target program to illustrate the high discovery potential possible in the charm and neutrino sectors. We highlight examples which are either unique to the program or difficult to accomplish at other venues.
Date:
December 2, 2011
Creator:
Adams, T.; Appel, J. A.; Arms, K. E.; Balantekin, A. B.; Conrad, J. M.; Cooper, P. S. et al.
Object Type:
Article
System:
The UNT Digital Library
CONFIRMATORY SURVEY RESULTS FOR PORTIONS OF THE ABB COMBUSTION ENGINEERING SITE IN WINDSOR, CONNECTICUT DURING THE FALL OF 2011
From the mid-1950s until mid-2000, the Combustion Engineering, Inc. (CE) site in Windsor, Connecticut (Figure A-1) was involved in the research, development, engineering, production, and servicing of nuclear fuels, systems, and services. The site is currently undergoing decommissioning that will lead to license termination and unrestricted release in accordance with the requirements of the License Termination Rule in 10 CFR Part 20, Subpart E. Asea Brown Boveri Incorporated (ABB) has been decommissioning the CE site since 2001.
Date:
December 9, 2011
Creator:
Adams, Wade C.
Object Type:
Report
System:
The UNT Digital Library
Urban Form Energy Use and Emissions in China: Preliminary Findings and Model Proof of Concept
Urbanization is reshaping China's economy, society, and energy system. Between 1990 and 2008 China added more than 300 million new urban residents, bringing the total urbanization rate to 46%. The ongoing population shift is spurring energy demand for new construction, as well as additional residential use with the replacement of rural biomass by urban commercial energy services. This project developed a modeling tool to quantify the full energy consequences of a particular form of urban residential development in order to identify energy- and carbon-efficient modes of neighborhood-level development and help mitigate resource and environmental implications of swelling cities. LBNL developed an integrated modeling tool that combines process-based lifecycle assessment with agent-based building operational energy use, personal transport, and consumption modeling. The lifecycle assessment approach was used to quantify energy and carbon emissions embodied in building materials production, construction, maintenance, and demolition. To provide more comprehensive analysis, LBNL developed an agent-based model as described below. The model was applied to LuJing, a residential development in Jinan, Shandong Province, to provide a case study and model proof of concept. This study produced results data that are unique by virtue of their scale, scope and type. Whereas most existing literature focuses on building-, …
Date:
December 15, 2010
Creator:
Aden, Nathaniel; Qin, Yining & Fridley, David
Object Type:
Report
System:
The UNT Digital Library
Status of Plasma Electron Hose Instability Studies in FACET
In the FACET plasma-wakefield acceleration experiment a dense 23 GeV electron beam will interact with lithium and cesium plasmas, leading to plasma ion-channel formation. The interaction between the electron beam and the plasma sheath-electrons may lead to a fast growing electron hose instability. By using optics dispersion knobs to induce a controlled z-x tilt along the beam entering the plasma, we investigate the transverse behavior of the beam in the plasma as function of the tilt. We seek to quantify limits on the instability in order to further explore potential limitations on future plasma wakefield accelerators due to the electron hose instability. The FACET plasma-wakefield experiment at SLAC will study beam driven plasma wakefield acceleration. A dense 23 GeV electron beam will interact with lithium or cesium plasma, leading to plasma ion-channel formation. The interaction between the electron beam and the plasma sheath-electrons drives the electron hose instability, as first studied by Whittum. While Ref. [2] indicates the possibility of a large instability growth rate for typical beam and plasma parameters, other studies including have shown that several physical effects may mitigate the hosing growth rate substantially. So far there has been no quantitative benchmarking of experimentally observed hosing in …
Date:
December 13, 2011
Creator:
Adli, Erik; England, Robert Joel; Frederico, Joel; Hogan, Mark; Li, Selina Zhao; Litos, Michael Dennis et al.
Object Type:
Article
System:
The UNT Digital Library
Evaluation of Performance, Reliability, and Risk for High Peak Power RF Sources from S-band through X-band for Advanced Accelerator Applications
None
Date:
December 12, 2012
Creator:
Adolphsen, C.; Jensen, A.; Pearson, C.; Sprehn, D. W.; Vlieks, A. E.; Wang, F. et al.
Object Type:
Article
System:
The UNT Digital Library
Beam Dynamics Study of X-Band Linac Driven X-Ray FELS
Several linac driven X-ray Free Electron Lasers (XFELs) are being developed to provide high brightness photon beams with very short, tunable wavelengths. In this paper, three XFEL configurations are proposed that achieve LCLS-like performance using X-band linac drivers. These linacs are more versatile, efficient and compact than ones using S-band or C-band rf technology. For each of the designs, the overall accelerator layout and the shaping of the bunch longitudinal phase space are described briefly. During the last 40 years, the photon wavelengths from linac driven FELs have been pushed shorter by increasing the electron beam energy and adopting shorter period undulators. Recently, the wavelengths have reached the X-ray range, with FLASH (Free-Electron Laser in Hamburg) and LCLS (Linac Coherent Light Source) successfully providing users with soft and hard X-rays, respectively. FLASH uses a 1.2 GeV L-band (1.3 GHz) superconducting linac driver and can deliver 10-70 fs FWHM long photon pulses in a wavelength range of 44 nm to 4.1 nm. LCLS uses the last third of the SLAC 3 km S-band (2.856 GHz) normal-conducting linac to produce 3.5 GeV to 15 GeV bunches to generate soft and hard X-rays with good spatial coherence at wavelengths from 2.2 nm to …
Date:
December 13, 2011
Creator:
Adolphsen, C.; Limborg-Deprey, C.; Raubenheimer, T. O.; Wu, J. & Sun, Y.
Object Type:
Article
System:
The UNT Digital Library
EVALUATION OF POTENTIAL ELUANTS FOR NON-ACID ELUTION OF CESIUM FROM RESORCINOL-FIRNAKDEGYDE RESUB
None
Date:
December 1, 2010
Creator:
Adu-Wusu, K.
Object Type:
Report
System:
The UNT Digital Library
Tank 26F-2F Evaporator Study
Tank 26F supernate sample was sent by Savannah River Remediation to Savannah River National Laboratory for evaporation test to help understand the underlying cause of the recent gravity drain line (GDL) pluggage during operation of the 2F Evaporator system. The supernate sample was characterized prior to the evaporation test. The evaporation test involved boiling the supernate in an open beaker until the density of the concentrate (evaporation product) was between 1.4 to 1.5 g/mL. It was followed by filtering and washing of the precipitated solids with deionized water. The concentrate supernate (or concentrate filtrate), the damp unwashed precipitated solids, and the wash filtrates were characterized. All the precipitated solids dissolved during water washing. A semi-quantitative X-ray diffraction (XRD) analysis on the unwashed precipitated solids revealed their composition. All the compounds with the exception of silica (silicon oxide) are known to be readily soluble in water. Hence, their dissolution during water washing is not unexpected. Even though silica is a sparingly water-soluble compound, its dissolution is also not surprising. This stems from its small fraction in the solids as a whole and also its relative freshness. Assuming similar supernate characteristics, flushing the GDL with water (preferably warm) should facilitate dissolution and …
Date:
December 19, 2012
Creator:
Adu-Wusu, K.
Object Type:
Report
System:
The UNT Digital Library
EVALUATION OF POTENTIAL ELUANTS FOR NON-ACID ELUTION OF CESIUM FROM RESORCINOL-FORMALDEHYDE RESIN
Small-column ion exchange (SCIX) units installed in high-level waste tanks to remove Cs-137 from highly alkaline salt solutions are among the waste treatment plans in the DOE-complex. Spherical Resorcinol-Formaldehyde (sRF) is the ion exchange resin selected for use in the Hanford Waste Treatment and Immobilization Plant (WTP). It is also the primary ion exchange material under consideration for SCIX at the Hanford site. The elution step of the multi-step ion exchange process is typically done with 0.5 M nitric acid. An acid eluant is a potential hazard in the event of a spill, leak, etc. because the high-level waste tanks are made of carbon steel. Corrosion and associated structural damage may ensue. A study has been conducted to explore non-acid elution as an alternative. Batch contact sorption equilibrium screening tests have been conducted with 36 potential non-acid eluants. The sorption tests involve equilibrating each cesium-containing eluant solution with the sRF resin for 48 hours at 25 C in a shaker oven. In the sorption tests, an eluant is deemed to have a high cesium elution potential if it minimizes cesium sorption onto the sRF resin. The top candidates (based on lowest cesium sorption distribution coefficients) include ammonium carbonate, ammonium carbonate/ammonium …
Date:
December 22, 2010
Creator:
Adu-Wusu, K. & Pennebaker, F.
Object Type:
Report
System:
The UNT Digital Library
Effect Of Changing Driving Conditions On Driver Behavior Towards Design Of A Safe And Efficient Traffic System
A report on driver behavior, satisfaction, and speed in Conventional Lane Merges versus Joint Lane Merges.
Date:
December 2013
Creator:
Aghazadeh, Fereydoun; Ikuma, Laura Hughes & Ishak, Sherif
Object Type:
Report
System:
The Portal to Texas History
Globalization, Worker Insecurity, and Policy Approaches
This report discusses the trends driving global economic integration, sources of worker insecurity and policy approaches. There appears to be a range of views on the merits of each of these policy approaches and the extent to which they can be designed and implemented in a way that would reduce worker insecurity without undermining the benefits of globalization.
Date:
December 22, 2011
Creator:
Ahearn, Raymond J.
Object Type:
Report
System:
The UNT Digital Library
Globalization, Worker Insecurity, and Policy Approaches
Today's global economy, or what many call globalization, has a growing impact on the economic futures of American companies, workers, and families. The current wave of globalization is supported by three broad trends: technology, increase in world supply of labor, and reduced government policies to international trade and investment.
Date:
December 22, 2011
Creator:
Ahearn, Raymond J.
Object Type:
Report
System:
The UNT Digital Library
International Trade and Finance: Key Policy Issues for the 112th Congress
This report highlights major international trade and finance issues Congress may address this year and next.
Date:
December 30, 2010
Creator:
Ahearn, Raymond J.
Object Type:
Report
System:
The UNT Digital Library
Trade Primer: Qs and As on Trade Concepts, Performance, and Policy
This report is divided into four sections in a question-and-answer format: trade concepts, U.S. trade performance, formulation of U.S. trade policy, and trade and investment issues. The first section on "Trade Concepts" deals with why countries trade, the consequences of trade expansion, and the relationship between globalization and trade. The second section, on trade performance, focuses on the U.S. trade deficit and its impact on industries. The third section deals with the roles played by the Executive Branch, Congress, the private sector, and the Judiciary in the formulation of U.S. trade policy. The fourth section, on U.S. trade and investment policy, asks questions related to trade negotiations and agreements and to imports, exports, and investments.
Date:
December 8, 2010
Creator:
Ahearn, Raymond J.
Object Type:
Report
System:
The UNT Digital Library
U.S.-EU Trade and Economic Relations: Key Policy Issues for the 112th Congress
U.S. and European private stakeholders, concerned about slow growth, job creation, and increased competition from emerging economies, have urged Brussels and Washington to strengthen transatlantic trade and economic ties by reducing or eliminating remaining trade barriers and by cooperating more closely in addressing global economic challenges. A select group of these issues are examined in this report.
Date:
December 22, 2011
Creator:
Ahearn, Raymond J.
Object Type:
Report
System:
The UNT Digital Library