The Dark Energy Spectrometer (DESpec): A Multi-Fiber Spectroscopic Upgrade of the Dark Energy Camera and Survey for the Blanco Telescope (open access)

The Dark Energy Spectrometer (DESpec): A Multi-Fiber Spectroscopic Upgrade of the Dark Energy Camera and Survey for the Blanco Telescope

None
Date: September 1, 2012
Creator: Abdalla, F.; Annis, J.; Bacon, D.; Bridle, S.; Castander, F.; Colless, M. et al.
Object Type: Report
System: The UNT Digital Library
Compact, Inexpensive, Safe, and Rapidly Refuelable Hydrogen Storage in Cryogenic Pressure Vessels (open access)

Compact, Inexpensive, Safe, and Rapidly Refuelable Hydrogen Storage in Cryogenic Pressure Vessels

None
Date: September 21, 2012
Creator: Aceves, S. M.; Petitpas, G.; Espinosa-Loza, F.; Matthews, M. J. & Ledesma-Orozco, E.
Object Type: Article
System: The UNT Digital Library
Observation of Two-Neutrino Double-Beta Decay in Xe-136 with EXO-200 (open access)

Observation of Two-Neutrino Double-Beta Decay in Xe-136 with EXO-200

We report the observation of two-neutrino double-beta decay in {sup 136}Xe with T{sub 1/2} = 2.11 {+-} 0.04(stat) {+-} 0.21(syst) x 10{sup 21} yr. This second-order process, predicted by the standard model, has been observed for several nuclei but not for {sup 136}Xe. The observed decay rate provides new input to matrix element calculations and to the search for the more interesting neutrinoless double-beta decay, the most sensitive probe for the existence of Majorana particles and the measurement of the neutrino mass scale.
Date: September 14, 2012
Creator: Ackerman, N.; Aharmim, B.; Auger, M.; Auty, D. J.; Barbeau, P. S.; Barry, K. et al.
Object Type: Article
System: The UNT Digital Library
Constraining Dark Matter Models from a Combined Analysis of Milky Way Satellites with the Fermi Large Area Telescope (open access)

Constraining Dark Matter Models from a Combined Analysis of Milky Way Satellites with the Fermi Large Area Telescope

Satellite galaxies of the Milky Way are among the most promising targets for dark matter searches in gamma rays. We present a search for dark matter consisting of weakly interacting massive particles, applying a joint likelihood analysis to 10 satellite galaxies with 24 months of data of the Fermi Large Area Telescope. No dark matter signal is detected. Including the uncertainty in the dark matter distribution, robust upper limits are placed on dark matter annihilation cross sections. The 95% confidence level upper limits range from about 10{sup -26} cm{sup 3} s{sup -1} at 5 GeV to about 5 x 10{sup -23} cm{sup 3} s{sup -1} at 1 TeV, depending on the dark matter annihilation final state. For the first time, using gamma rays, we are able to rule out models with the most generic cross section ({approx}3 x 10{sup -26} cm{sup 3} s{sup -1} for a purely s-wave cross section), without assuming additional boost factors.
Date: September 14, 2012
Creator: Ackermann, M.; Ajello, M.; Albert, A.; Atwood, W. B.; Baldini, L.; Ballet, J. et al.
Object Type: Article
System: The UNT Digital Library
In-Flight Measurement of the Absolute Energy Scale of the Fermi Large Area Telescope (open access)

In-Flight Measurement of the Absolute Energy Scale of the Fermi Large Area Telescope

The Large Area Telescope (LAT) on-board the Fermi Gamma-ray Space Telescope is a pair-conversion telescope designed to survey the gamma-ray sky from 20 MeV to several hundreds of GeV. In this energy band there are no astronomical sources with sufficiently well known and sharp spectral features to allow an absolute calibration of the LAT energy scale. However, the geomagnetic cutoff in the cosmic ray electron-plus-positron (CRE) spectrum in low Earth orbit does provide such a spectral feature. The energy and spectral shape of this cutoff can be calculated with the aid of a numerical code tracing charged particles in the Earth's magnetic field. By comparing the cutoff value with that measured by the LAT in different geomagnetic positions, we have obtained several calibration points between {approx}6 and {approx}13 GeV with an estimated uncertainty of {approx}2%. An energy calibration with such high accuracy reduces the systematic uncertainty in LAT measurements of, for example, the spectral cutoff in the emission from gamma ray pulsars.
Date: September 20, 2012
Creator: Ackermann, M.; Ajello, M.; Allafort, A.; Atwood, W. B.; Axelsson, M.; Baldini, L. et al.
Object Type: Article
System: The UNT Digital Library
Improving Conservation for First-Order System Least Squares Finite-Element Methods (open access)

Improving Conservation for First-Order System Least Squares Finite-Element Methods

None
Date: September 5, 2012
Creator: Adler, J H & Vassilevski, P S
Object Type: Article
System: The UNT Digital Library
Gravitomagnetism and Spinor Quantum Mechanics (open access)

Gravitomagnetism and Spinor Quantum Mechanics

We give a systematic treatment of a spin 1=2 particle in a combined electromagnetic field and a weak gravitational field that is produced by a slowly moving matter source. This paper continues previous work on a spin zero particle, but it is largely self-contained and may serve as an introduction to spinors in a Riemann space. The analysis is based on the Dirac equation expressed in generally covariant form and coupled minimally to the electromagnetic field. The restriction to a slowly moving matter source, such as the earth, allows us to describe the gravitational field by a gravitoelectric (Newtonian) potential and a gravitomagnetic (frame-dragging) vector potential, the existence of which has recently been experimentally verified. Our main interest is the coupling of the orbital and spin angular momenta of the particle to the gravitomagnetic field. Specifically we calculate the gravitational gyromagnetic ratio as g{sub g} = 1 ; this is to be compared with the electromagnetic gyromagnetic ratio of g{sub e} = 2 for a Dirac electron.
Date: September 14, 2012
Creator: Adler, Ronald J.; /Stanford U., HEPL /San Francisco State U.; Chen, Pisin; /Taiwan, Natl. Taiwan U. /KIPAC, Menlo Park /SLAC; Varani, Elisa & /Unlisted
Object Type: Article
System: The UNT Digital Library
Fermi Large Area Telescope Observations of the Supernova Remnant G8.7-0.1 (open access)

Fermi Large Area Telescope Observations of the Supernova Remnant G8.7-0.1

We present a detailed analysis of the GeV gamma-ray emission toward the supernova remnant (SNR) G8.7-0.1 with the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope. An investigation of the relationship between G8.7-0.1 and the TeV unidentified source HESS J1804-216 provides us with an important clue on diffusion process of cosmic rays if particle acceleration operates in the SNR. The GeV gamma-ray emission is extended with most of the emission in positional coincidence with the SNR G8.7-0.1 and a lesser part located outside the western boundary of G8.7-0.1. The region of the gamma-ray emission overlaps spatially connected molecular clouds, implying a physical connection for the gamma-ray structure. The total gamma-ray spectrum measured with LAT from 200 MeV-100 GeV can be described by a broken power-law function with a break of 2.4 {+-} 0.6 (stat) {+-} 1.2 (sys) GeV, and photon indices of 2.10 {+-} 0.06 (stat) {+-} 0.10 (sys) below the break and 2.70 {+-} 0.12 (stat) {+-} 0.14 (sys) above the break. Given the spatial association among the gamma rays, the radio emission of G8.7-0.1, and the molecular clouds, the decay of p0s produced by particles accelerated in the SNR and hitting the molecular clouds naturally …
Date: September 14, 2012
Creator: Ajello, M.; Allafort, A.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D. et al.
Object Type: Article
System: The UNT Digital Library
Cyber Security Challenges in Using Cloud Computing in the Electric Utility Industry (open access)

Cyber Security Challenges in Using Cloud Computing in the Electric Utility Industry

This document contains introductory material that discusses cyber security challenges in using cloud computing in the electric utility industry.
Date: September 1, 2012
Creator: Akyol, Bora A.
Object Type: Report
System: The UNT Digital Library
Impact of Contaminants Present in Coal-Biomass Derived Synthesis Gas on Water-gas Shift and Fischer-Tropsch Synthesis Catalysts (open access)

Impact of Contaminants Present in Coal-Biomass Derived Synthesis Gas on Water-gas Shift and Fischer-Tropsch Synthesis Catalysts

Co-gasification of biomass and coal in large-scale, Integrated Gasification Combined Cycle (IGCC) plants increases the efficiency and reduces the environmental impact of making synthesis gas ("syngas") that can be used in Coal-Biomass-to-Liquids (CBTL) processes for producing transportation fuels. However, the water-gas shift (WGS) and Fischer-Tropsch synthesis (FTS) catalysts used in these processes may be poisoned by multiple contaminants found in coal-biomass derived syngas; sulfur species, trace toxic metals, halides, nitrogen species, the vapors of alkali metals and their salts (e.g., KCl and NaCl), ammonia, and phosphorous. Thus, it is essential to develop a fundamental understanding of poisoning/inhibition mechanisms before investing in the development of any costly mitigation technologies. We therefore investigated the impact of potential contaminants (H{sub 2}S, NH{sub 3}, HCN, AsH{sub 3}, PH{sub 3}, HCl, NaCl, KCl, AS{sub 3}, NH{sub 4}NO{sub 3}, NH{sub 4}OH, KNO{sub 3}, HBr, HF, and HNO{sub 3}) on the performance and lifetime of commercially available and generic (prepared in-house) WGS and FT catalysts; ferrochrome-based high-temperature WGS catalyst (HT-WGS, Shiftmax 120™, Süd-Chemie), low-temperature Cu/ZnO-based WGS catalyst (LT-WGS, Shiftmax 230™, Süd-Chemie), and iron- and cobalt-based Fischer-Trospch synthesis catalysts (Fe-FT & Co-FT, UK-CAER). In this project, TDA Research, Inc. collaborated with a team at the University of Kentucky …
Date: September 30, 2012
Creator: Alptekin, Gokhan
Object Type: Report
System: The UNT Digital Library
A Low Cost, High Capacity Regenerable Sorbent for Pre-combustion CO{sub 2} Capture (open access)

A Low Cost, High Capacity Regenerable Sorbent for Pre-combustion CO{sub 2} Capture

The overall objective of the proposed research is to develop a low cost, high capacity CO{sub 2} sorbent and demonstrate its technical and economic viability for pre-combustion CO{sub 2} capture. The specific objectives supporting our research plan were to optimize the chemical structure and physical properties of the sorbent, scale-up its production using high throughput manufacturing equipment and bulk raw materials and then evaluate its performance, first in bench-scale experiments and then in slipstream tests using actual coal-derived synthesis gas. One of the objectives of the laboratory-scale evaluations was to demonstrate the life and durability of the sorbent for over 10,000 cycles and to assess the impact of contaminants (such as sulfur) on its performance. In the field tests, our objective was to demonstrate the operation of the sorbent using actual coal-derived synthesis gas streams generated by air-blown and oxygen-blown commercial and pilot-scale coal gasifiers (the CO{sub 2} partial pressure in these gas streams is significantly different, which directly impacts the operating conditions hence the performance of the sorbent). To support the field demonstration work, TDA collaborated with Phillips 66 and Southern Company to carry out two separate field tests using actual coal-derived synthesis gas at the Wabash River IGCC …
Date: September 30, 2012
Creator: Alptekin, Gokhan
Object Type: Report
System: The UNT Digital Library
INDEPENDENT VERIFICATION SURVEY SUMMARY AND RESULTS FOR SUB-SLAB SOILS ASSOCIATED WITH THE FORMER BUILDING K-33, OAK RIDGE, TENNESSEE (open access)

INDEPENDENT VERIFICATION SURVEY SUMMARY AND RESULTS FOR SUB-SLAB SOILS ASSOCIATED WITH THE FORMER BUILDING K-33, OAK RIDGE, TENNESSEE

At DOE’s request, ORAU conducted confirmatory surveys of the K-33 sub-slab soil during the period of August 2011 through May 2012. The survey activities included visual inspections and measurement and sampling activities. LSRS was forthcoming with information relating to surface scan results. Scans performed by the contractor were of adequate coverage and overall data appear to represent actual site conditions. However, the LSRS technicians failed to identify several areas of elevated direct gamma radiation. Most of the samples taken by ORAU at locations of elevated instrument response were above the remediation concentration for one or more radionuclides of concern (ROC). The contractor was, however, quick to perform additional remediation of areas identified to have contamination above the guidelines. Further investigation by ORAU was not requested once additional remediation was completed. It is presumed the remediation contractor’s future PCCR will present detailed and conclusive evidence that K-33 sub-slab soils either comply or do not comply with record of decision (ROD) criteria. However, ORAU concludes, based on both independent verification (IV) data and data provided by LSRS, that the remediation contractor followed appropriate and applicable procedures and that the associated data adequately represent site conditions.
Date: September 20, 2012
Creator: Altic, Nick A.
Object Type: Report
System: The UNT Digital Library
Higgs, Binos and Gluinos: Split Susy within Reach (open access)

Higgs, Binos and Gluinos: Split Susy within Reach

Recent results from the LHC for the Higgs boson with mass between 142 GeV {approx}< m{sub h{sup 0}} {approx}< 147 GeV points to PeV-scale Split Supersymmetry. This article explores the consequences of a Higgs mass in this range and possible discovery modes for Split Susy. Moderate lifetime gluinos, with decay lengths in the 25 {micro}m to 10 yr range, are its imminent smoking gun signature. The 7TeV LHC will be sensitive to the moderately lived gluinos and trilepton signatures from direct electroweakino production. Moreover, the dark matter abundance may be obtained from annihilation through an s-channel Higgs resonance, with the LSP almost purely bino and mass m{sub {chi}{sub 1}{sup 0}} {approx_equal} 70 GeV. The Higgs resonance region of Split Susy has visible signatures in dark matter direct and indirect detection and electric dipole moment experiments. If the anomalies go away, the majority of Split Susy parameter space will be excluded.
Date: September 14, 2012
Creator: Alves, Daniele S.M.; Izaguirre, Eder; /SLAC /Stanford U., Phys. Dept.; Wacker, Jay G. & /SLAC /Stanford U., ITP
Object Type: Article
System: The UNT Digital Library
Technical feasibility of storage on large dish stirling systems. (open access)

Technical feasibility of storage on large dish stirling systems.

None
Date: September 1, 2012
Creator: Andraka, Charles E.; Rawlinson, Kim Scott & Siegel, Nathan Phillip (Bucknell University, Lewisburg, PA)
Object Type: Report
System: The UNT Digital Library
Optical Measurement Technologies for High Temperature, Radiation Exposure, and Corrosive Environments—Significant Activities and Findings: In-vessel Optical Measurements for Advanced SMRs (open access)

Optical Measurement Technologies for High Temperature, Radiation Exposure, and Corrosive Environments—Significant Activities and Findings: In-vessel Optical Measurements for Advanced SMRs

Development of advanced Small Modular Reactors (aSMRs) is key to providing the United States with a sustainable, economically viable, and carbon-neutral energy source. The aSMR designs have attractive economic factors that should compensate for the economies of scale that have driven development of large commercial nuclear power plants to date. For example, aSMRs can be manufactured at reduced capital costs in a factory and potentially shorter lead times and then be shipped to a site to provide power away from large grid systems. The integral, self-contained nature of aSMR designs is fundamentally different than conventional reactor designs. Future aSMR deployment will require new instrumentation and control (I&C) architectures to accommodate the integral design and withstand the extreme in-vessel environmental conditions. Operators will depend on sophisticated sensing and machine vision technologies that provide efficient human-machine interface for in-vessel telepresence, telerobotic control, and remote process operations. The future viability of aSMRs is dependent on understanding and overcoming the significant technical challenges involving in-vessel reactor sensing and monitoring under extreme temperatures, pressures, corrosive environments, and radiation fluxes
Date: September 1, 2012
Creator: Anheier, Norman C.; Cannon, Bret D.; Qiao, Hong (Amy) & Suter, Jonathan D.
Object Type: Report
System: The UNT Digital Library
International benchmark calculations of field experiments at the Asse Salt Mine. (open access)

International benchmark calculations of field experiments at the Asse Salt Mine.

None
Date: September 1, 2012
Creator: Arguello, Jose Guadalupe, Jr.; Holland, John Francis & Bean, James E.
Object Type: Report
System: The UNT Digital Library
Nature versus nurture in cellular behavior and disease. (open access)

Nature versus nurture in cellular behavior and disease.

None
Date: September 1, 2012
Creator: Ashley, Carlee E.; Carnes, Eric C.; Kaehr, Bryan James; Harper, Jason C. & Brinker, C. Jeffrey
Object Type: Report
System: The UNT Digital Library
Silo Storage Preconceptual Design (open access)

Silo Storage Preconceptual Design

The National Nuclear Security Administration (NNSA) has a need to develop and field a low-cost option for the long-term storage of a variety of radiological material. The storage option’s primary requirement is to provide both environmental and physical protection of the materials. Design criteria for this effort require a low initial cost and minimum maintenance over a 50-year design life. In 1999, Argonne National Laboratory-West was tasked with developing a dry silo storage option for the BN-350 Spent Fuel in Aktau Kazakhstan. Argon’s design consisted of a carbon steel cylinder approximately 16 ft long, 18 in. outside diameter and 0.375 in. wall thickness. The carbon steel silo was protected from corrosion by a duplex coating system consisting of zinc and epoxy. Although the study indicated that the duplex coating design would provide a design life well in excess of the required 50 years, the review board was concerned because of the novelty of the design and the lack of historical use. In 2012, NNSA tasked Idaho National Laboratory (INL) with reinvestigating the silo storage concept and development of alternative corrosion protection strategies. The 2012 study, “Silo Storage Concepts, Cathodic Protection Options Study” (INL/EST-12-26627), concludes that the option which best fits …
Date: September 1, 2012
Creator: Austad, Stephanie L.; Bragassa, Patrick W.; Croft, Kevin M; Ferguson, David S; Gladson, Scott C; Shafer, Annette L et al.
Object Type: Report
System: The UNT Digital Library
Use of Polycarbonate Vacuum Vessels in High-Temperature Fusion-Plasma Research (open access)

Use of Polycarbonate Vacuum Vessels in High-Temperature Fusion-Plasma Research

Magnetic fusion energy (MFE) research requires ultrahigh-vacuum (UHV) conditions, primarily to reduce plasma contamination by impurities. For radiofrequency (RF)-heated plasmas, a great benefit may accrue from a non-conducting vacuum vessel, allowing external RF antennas which avoids the complications and cost of internal antennas and high-voltage high-current feedthroughs. In this paper we describe these and other criteria, e.g., safety, availability, design flexibility, structural integrity, access, outgassing, transparency, and fabrication techniques that led to the selection and use of 25.4-cm OD, 1.6-cm wall polycarbonate pipe as the main vacuum vessel for an MFE research device whose plasmas are expected to reach keV energies for durations exceeding 0.1 s
Date: September 27, 2012
Creator: B. Berlinger, A. Brooks, H. Feder, J. Gumbas, T. Franckowiak and S.A. Cohen
Object Type: Article
System: The UNT Digital Library
NUCLEAR ENERGY AND ASTROPHYSICS APPLICATIONS OF ENDF/B-VII.1 EVALUATED NUCLEAR LIBRARY (open access)

NUCLEAR ENERGY AND ASTROPHYSICS APPLICATIONS OF ENDF/B-VII.1 EVALUATED NUCLEAR LIBRARY

N/A
Date: September 3, 2012
Creator: B., Pritychenko
Object Type: Article
System: The UNT Digital Library
Accident Analysis for the NIST Research Reactor Before and After Fuel Conversion (open access)

Accident Analysis for the NIST Research Reactor Before and After Fuel Conversion

Postulated accidents have been analyzed for the 20 MW D2O-moderated research reactor (NBSR) at the National Institute of Standards and Technology (NIST). The analysis has been carried out for the present core, which contains high enriched uranium (HEU) fuel and for a proposed equilibrium core with low enriched uranium (LEU) fuel. The analyses employ state-of-the-art calculational methods. Three-dimensional Monte Carlo neutron transport calculations were performed with the MCNPX code to determine homogenized fuel compositions in the lower and upper halves of each fuel element and to determine the resulting neutronic properties of the core. The accident analysis employed a model of the primary loop with the RELAP5 code. The model includes the primary pumps, shutdown pumps outlet valves, heat exchanger, fuel elements, and flow channels for both the six inner and twenty-four outer fuel elements. Evaluations were performed for the following accidents: (1) control rod withdrawal startup accident, (2) maximum reactivity insertion accident, (3) loss-of-flow accident resulting from loss of electrical power with an assumption of failure of shutdown cooling pumps, (4) loss-of-flow accident resulting from a primary pump seizure, and (5) loss-of-flow accident resulting from inadvertent throttling of a flow control valve. In addition, natural circulation cooling at low …
Date: September 30, 2012
Creator: Baek, J.; Diamond, D.; Cuadra, A.; Hanson, A. L.; Cheng, L. Y. & Brown, N. R.
Object Type: Report
System: The UNT Digital Library
FINAL REPORT FOR INDEPENDENT CONFIRMATORY SURVEY SUMMARY AND RESULTS FOR THE HEMATITE DECOMMISSIONING PROJECT, FESTUS, MISSOURI (open access)

FINAL REPORT FOR INDEPENDENT CONFIRMATORY SURVEY SUMMARY AND RESULTS FOR THE HEMATITE DECOMMISSIONING PROJECT, FESTUS, MISSOURI

ORAU conducted confirmatory surveys of the Hematite site during the period of June 12 through June 13, 2012. The survey activities included in-process inspections, document review, walkover surveys, sampling activities, and laboratory analysis of split samples. WEC was forthcoming with information relating to practices, procedures, and surface scan results. Scans performed by the WEC technician were extremely thorough and methodical. The WEC and ORAU technicians identified the same areas of elevated activity with comparable detector responses. WEC sampling of re-use soils, waste soils, sediments, and groundwater were conducted under ORAU observation. The sampling efforts observed by ORAU were performed in accordance with site-specific procedures and in a manner sufficient to provide quality supporting data. Three observations were made during groundwater sampling activities. First, the water level indicator was re-used without submitting rinse blank. Second, bubbles created during tubing extraction could indicate the presence of volatilized organic compounds. Third, samplers did not use a photo ionization detector prior to sample collection to indicate the presence of volatile organic vapors. Results of split samples indicated a high level of comparability between the WEC and ORAU/ORISE radiological laboratories. Analytical practices and procedures appear to be sufficient in providing quality radiochemical data. All concentrations …
Date: September 21, 2012
Creator: Bailey, Erika N. & Lee, Jason D.
Object Type: Report
System: The UNT Digital Library
X-ray thomson scattering measurements of warm dense matter. (open access)

X-ray thomson scattering measurements of warm dense matter.

None
Date: September 1, 2012
Creator: Bailey, James E.; Ao, Tommy; Harding, Eric; Hansen, Stephanie B.; Desjarlais, Michael Paul; Lemke, Raymond William et al.
Object Type: Report
System: The UNT Digital Library
Effective Grid Utilization: A Technical Assessment and Application Guide; April 2011 - September 2012 (open access)

Effective Grid Utilization: A Technical Assessment and Application Guide; April 2011 - September 2012

In order to more fully integrate renewable resources, such as wind and solar, into the transmission system, additional capacity must be realized in the short term using the installed transmission capacity that exists today. The U.S. Department of Energy (DOE) and the National Renewable Energy Laboratory Transmission and Grid Integration Group supported this study to assemble the history of regulations and status of transmission technology to expand existing grid capacity. This report compiles data on various transmission technology methods and upgrades for increased capacity utilization of the existing transmission system and transmission corridors. The report discusses the technical merit of each method and explains how the method could be applied within the current regulatory structure to increase existing transmission conductor and/or corridor capacity. The history and current state of alternatives to new construction is presented for regulators, legislators, and other policy makers wrestling with issues surrounding integration of variable generation. Current regulations are assessed for opportunities to change them to promote grid expansion. To support consideration of these alternatives for expanding grid capacity, the report lists relevant rules, standards, and policy changes.
Date: September 1, 2012
Creator: Balser, S.; Sankar, S.; Miller, R.; Rawlins, A.; Israel, M.; Curry, T. et al.
Object Type: Report
System: The UNT Digital Library