133,939 Matching Results

Search Results

prev Results: 49 - 72 next
open access

Diagnostics for the Biased Electrode Experiment on NSTX

Description: A linear array of four small biased electrodes was installed in NSTX in an attempt to control the width of the scrape-off layer (SOL) by creating a strong local poloidal electric field. The set of electrodes were separated poloidally by a 1 cm gap between electrodes and were located slightly below the midplane of NSTX, 1 cm behind the RF antenna and oriented so that each electrode is facing approximately normal to the magnetic field. Each electrode can be independently biased to ±100 volts. Pre… more
Date: March 20, 2009
Creator: A.L. Roquemore, S.J. Zweben, C.E. Bush, R. Kaita, R. J. Marsalsa, and R.J. Maqueda
Partner: UNT Libraries Government Documents Department
open access

A Rosetta Stone Relating Conventions In Photo-Meson Partial Wave Analyses

Description: A new generation of complete experiments in pseudoscalar meson photo-production is being pursued at several laboratories. While new data are emerging, there is some confusion regarding definitions of asymmetries and the conventions used in partial wave analyses (PWA). We present expressions for constructing asymmetries as coordinate-system independent ratios of cross sections, along with the names used for these ratios by different PWA groups.
Date: April 1, 2012
Creator: A.M. Sandorfi, B. Dey, A. Sarantsev, L. Tiator, R. Workman
Partner: UNT Libraries Government Documents Department
open access

Nonforward parton distributions

Description: Applications of perturbative QCD to deeply virtual Compton scattering and hard exclusive electroproduction processes require a generalization of usual parton distributions for the case when long-distance information is accumulated in nonforward matrix elements <p{prime}{vert_bar}O(0,x){vert_bar}p> of quark and gluon light-cone operators. They describe two types of nonperturbative functions parameterizing such matrix elements: double distributions F(x,y;t) and nonforward distribution funct… more
Date: April 1, 1997
Creator: A.Radyushkin
Partner: UNT Libraries Government Documents Department
open access

F(1) for B (forward) D*ln from lattice QCD

Description: The authors would like to determine |V{sub cb}| from the exclusive semi-leptonic decay B{yields}D*lv. The differential decay rate is d{Lambda}/dw = G{sub F}{sup 2}/4{pi}{sup 3}(w{sup 2}-1){sup 1/2}m{sub D*}{sup 3} (m{sub B}-m{sub D*}){sup 2}G(w)|V{sub cb}|{sup 2}|F{sub B{yields}D*}(w)|{sup 2}, where w = v {center_dot} v{prime} and G(1) = 1. At zero recoil (w = 1) heavy-quark symmetry requires F{sub B{yields}D*}(1) to be close to 1. So, |V{sub cb}| is determined by dividing measurements of d{Lam… more
Date: July 12, 2002
Creator: A.S. Kronfeld, P.B. Mackenzie and J.N. Simone
Partner: UNT Libraries Government Documents Department
open access

Onset and Saturation of Ion Heating by Odd-parity Rotating-magnetic-fields in a Field-reversed Configuration

Description: Heating of figure-8 ions by odd-parity rotating magnetic fields (RMFο) applied to an elongated field-reversed configuration (FRC) is investigated. The largest energy gain occurs at resonances (s ≡ ω(sub)R⁄ω) of the RMFο frequency, ω(sub)R, with the figure-8 orbital frequency, ω, and is proportional to s^2 for s – even resonances and to s for s – odd resonances. The threshold for the transition from regular to stochastic orbits explains both the onset and saturation of heating. The FRC magnetic … more
Date: November 1, 2005
Creator: A.S. Landsman, S.A. Cohen, A.H. Glasser
Partner: UNT Libraries Government Documents Department
open access

Effects of the Thickness of Niobium Surface Oxide Layers on Field Emission

Description: Field emission on the inner surfaces of niobium superconducting radio frequency cavities is still one of the major obstacles for reaching high accelerating gradients for SRF community. Our previous experimental results* seemed to imply that the threshold of field emission was related to the thickness of Nb surface oxide layers. In this contribution, a more detailed study on the influences of the surface oxide layers on the field emission on Nb surfaces will be reported. By anodization technique… more
Date: September 1, 2011
Creator: A.T. Wu, S. Jin, J.D. Mammosser, R.A. Rimmer, X.Y. Lu, K. Zhao
Partner: UNT Libraries Government Documents Department
open access

Fastest Electropolishing Technique on Niobium for Particle Accelerators

Description: Field emission on the inner surfaces of niobium (Nb) superconducting radio frequency (SRF) cavities is still one of the major obstacles for reaching high accelerating gradients for SRF community. Our previous experimental results [1] seemed to imply that the threshold of field emission was related to the thickness of Nb surface oxide layers. In this contribution, a more detailed study on the influences of the surface oxide layers on the field emission on Nb surfaces will be reported. By anodiza… more
Date: September 1, 2011
Creator: A.T. Wu, S. Jin, R.A. Rimmer, X.Y. Lu, K. Zhao
Partner: UNT Libraries Government Documents Department
open access

Progress of Bep Treatments on Nb at JLAB

Description: Recent experimental results have indicated that Buffered Electropolishing (BEP) is a promising candidate for the next generation of surface treatment technique for Nb superconducting radio frequency (SRF) cavities to be used in particle accelerators. In order to lay the foundation for using BEP as the next generation surface treatment technique for Nb SRF cavities, some fundamental aspects of BEP treatments for Nb have to be investigated. In this report, recent progress on BEP study at JLab is … more
Date: May 1, 2010
Creator: A.T. Wu, S. Jin, R.A. Rimmer,X.Y. Lu, K. Zhao
Partner: UNT Libraries Government Documents Department
open access

Using GIS to Identify Remediation Areas in Landfills

Description: This paper reports the use of GIS mapping software—ArcMap and ArcInfo Workstation—by the Idaho National Engineering and Environmental Laboratory (INEEL) as a non-intrusive method of locating and characterizing radioactive waste in a 97-acre landfill to aid in planning cleanup efforts. The fine-scale techniques and methods used offer potential application for other burial sites for which hazards indicate a non-intrusive approach. By converting many boxes of paper shipping records in multiple for… more
Date: August 1, 2004
Creator: A.Tedrow, Linda
Partner: UNT Libraries Government Documents Department
open access

Images of Quark Intrinsic Motion in Covariant Parton Model

Description: We discuss the relations between TMDs and PDFs in the framework of the covariant parton model. The quark OAM and its connection to TMDs are studied as well.
Date: April 1, 2010
Creator: A.V. Efremov, P. Schweitzer, O.V. Teryaev, P. Zavada
Partner: UNT Libraries Government Documents Department
open access

QCD sum rule calculation of {gamma}{gamma}{sup *} {r_arrow} {pi}{sup 0} transition form factor

Description: The authors develop a QCD sum rule analysis of the form factor F{sub {gamma}{sup *}{gamma}{sup *}{pi}{sup 0}}(q{sup 2},Q{sup 2}) in the region where virtuality of one of the spacelike photons is small q{sup 2} {much_lt} 1 GeV{sup 2} while another is large: Q{sup 2} {approx_gt} 1 GeV{sup 2}. They construct the operator product expansion suitable for this kinematic situation and obtain a QCD sum rule for F{sub {gamma}{sup *}{gamma}{sup *}{pi}{sup 0}}(0, Q{sup 2}). Their results confirm expectatio… more
Date: November 1, 1995
Creator: A.V.Radyushkin & R.T.Ruskov
Partner: UNT Libraries Government Documents Department
open access

EFFECT OF GLASS-BATCH MAKEUP ON THE MELTING PROCESS

Description: The response of a glass batch to heating is determined by the batch makeup and in turn determines the rate of melting. Batches formulated for a high-alumina nuclear waste to be vitrified in an all-electric melter were heated at a constant temperature-increase rate to determine changes in melting behavior in response to the selection of batch chemicals and silica grain-size as well as the addition of heat-generating reactants. The type of batch materials and the size of silica grains determine h… more
Date: December 7, 2010
Creator: AA, KRUGER & P, HRMA
Partner: UNT Libraries Government Documents Department
open access

CRYSTALLIZATION IN HIGH-LEVEL WASTE GLASSES U.S. DEPARTMENT OF ENERGY OFFICE OF RIVER PROTECTION WTP ENGINEERING DIVISION

Description: Various circumstances influence crystallization in glassmaking, for example: (1) crystals nucleate and grow before the glass-forming melt occurs; (2) crystals grow or dissolve in flowing melt and during changing temperature; (3) crystals move under the influence of gravity; (4) crystals agglomerate and interact with gas bubbles; (5) high-level wastes (HLW) are mixtures of a large number of components in unusual proportions; (6) melter processing of HLW and the slow cooling of HLW glass in canis… more
Date: August 19, 2009
Creator: AA, KRUGER & PR, HRMA
Partner: UNT Libraries Government Documents Department
open access

CRYSTALLIZATION IN MULTICOMPONENT GLASSES

Description: In glass processing situations involving glass crystallization, various crystalline forms nucleate, grow, and dissolve, typically in a nonuniform temperature field of molten glass subjected to convection. Nuclear waste glasses are remarkable examples of multicomponent vitrified mixtures involving partial crystallization. In the glass melter, crystals form and dissolve during batch-to-glass conversion, melter processing, and product cooling. Crystals often agglomerate and sink, and they may sett… more
Date: October 8, 2009
Creator: AA, KRUGER & PR, HRMA
Partner: UNT Libraries Government Documents Department
open access

NUCLEAR WASTE GLASSES CONTINUOUS MELTING AND BULK VITRIFICAITON

Description: This contribution addresses various aspects of nuclear waste vitrification. Nuclear wastes have a variety of components and composition ranges. For each waste composition, the glass must be formulated to possess acceptable processing and product behavior defined in terms of physical and chemical properties that guarantee the glass can be easily made and resist environmental degradation. Glass formulation is facilitated by developing property-composition models, and the strategy of model develop… more
Date: March 24, 2008
Creator: AA, KRUGER & PR, HRMA
Partner: UNT Libraries Government Documents Department
open access

HIGH ALUMINUM HLW (HIGH LEVEL WASTE ) GLASSES FOR HANFORDS WTP (WASTE TREATMENT PROJECT)

Description: This paper presents the results of glass formulation development and melter testing to identify high waste loading glasses to treat high-Al high level waste (HLW) at Hanford. Previous glass formulations developed for this HLW had high waste loadings but their processing rates were lower that desired. The present work was aimed at improving the glass processing rate while maintaining high waste loadings. Glass formulations were designed, prepared at crucible-scale and characterized to determine … more
Date: January 4, 2010
Creator: AA, KRUGER; BW, BOWAN; I, JOSEPH; H, GAN; WK, KOT; KS, MATLACK et al.
Partner: UNT Libraries Government Documents Department
open access

GLASSES CONTAINING IRON (II III) OXIDES FOR IMMOBILIZATION OF RADIOACTIVE TECHNETIUM

Description: Technetium-99 (Tc-99) has posed serious environmental threats as US Department of Energy's high-level waste. This work reports the vitrification of Re, as surrogate for Tc-99, by iron-borosilicate and iron-phosphate glasses, respectively. Iron-phosphate glasses can dissolve Re as high as {approx} 1.2 wt. %, which can become candidate waste forms for Tc-99 disposal, while borosilicate glasses can retain less than 0.1 wt. % of Re due to high melting temperature and long melting duration. Vitrific… more
Date: November 7, 2011
Creator: AA, KRUGER; J, HEO; K, XU; JK, CHOI; PR, HRMA & W, UM
Partner: UNT Libraries Government Documents Department
open access

IRON-PHOSPHATE GLASS FOR IMMOBILIZATION OF RADIOACTIVE TECHNETIUM

Description: Technetium-99 (Tc-99) can bring a serious environmental threat because of its high fission yield, long half-life, and high solubility and mobility in the ground water. The present work investigated the immobilization of Tc-99 (surrogated by Re) by heat-treating mixtures of an iron-phosphate glass with 1.5 to 6 wt.% KReO{sub 4} at {approx}1000 C. The Re retention in the glass was as high as {approx}1.2 wt. % while the loss of Re by evaporation during melting was {approx}50%. Re was uniformly dis… more
Date: March 19, 2012
Creator: AA, KRUGER; PR, HRMA; K, XU; J, CHOI; W, UM & J, HEO
Partner: UNT Libraries Government Documents Department
open access

EVALUATION OF TEMPORAL VARIATIONS IN HYDRAULIC CAPTURE DUE TO CHANGING FLOW PATTERNS USING MAPPING AND MODELING TECHNIQUES

Description: Robust performance evaluation represents one of the most challenging aspects of groundwater pump-and-treat (P&T) remedy implementation. In most cases, the primary goal of the P&T system is hydraulic containment, and ultimately recovery, of contaminants to protect downgradient receptors. Estimating the extent of hydraulic containment is particularly challenging under changing flow patterns due to variable pumping, boundaries and/or other conditions. We present a systematic approach to es… more
Date: April 7, 2011
Creator: AA, SPILIOTOPOULOS; LC, SWANSON; R, SHANNON & MJ, TONKIN
Partner: UNT Libraries Government Documents Department
open access

A MOBILE MELT-DILUTE MODULE FOR THE TREATMENT OF ALUMINUM RESEARCH REACTOR SPENT FUEL

Description: A mobile melt-dilute (MMD) module for the treatment of aluminum research reactor spent fuel is being developed jointly by the Savannah River National Laboratory and Argonne National Laboratory. The process uses a closed system approach to retain fission products/gases inside a sealed canister after treatment. The MMD process melts and dilutes spent fuel with depleted uranium to obtain an isotopic content of less than 20 percent. The final ingot is solidified inside the sealed canister and can b… more
Date: November 3, 2004
Creator: ADAMS, THAD
Partner: UNT Libraries Government Documents Department
open access

Micromilling of Metal Alloys with Focused Ion Beam-Fabricated Tools

Description: This work combines focused ion beam sputtering and ultra-precision machining as a first step in fabricating microstructure in metals and alloys. Specifically, {approx}25{micro}m diameter micro-end mills are made from cobalt M42 high-speed steel and C2 micrograin tungsten carbide tool blanks by ion beam sputtering. A 20 keV focused gallium beam defines tool cutting edges having radii of curvature < 0.1{micro}m. Micro-end mills having 2, 4 and 5 cutting edges successfully machine small trenche… more
Date: November 5, 1999
Creator: ADAMS,DAVID P.; VASILE,M.J.; BENAVIDES,GILBERT L. & CAMPBELL,ANN N.
Partner: UNT Libraries Government Documents Department
open access

Sorption of Cesium From Aqueous Waste Solution on SuperLig 644 Resin

Description: The removal of cesium from aqueous waste solution was investigated in a column setup using SuperLig(R) 644 resin. The resin was significantly coarser in size than those used in previous studies because of hydraulic problems encountered during pilot-scale tests. The bed volume (BV = 140) at the onset of breakthrough surpassed the design requirement of 100 BV at 50 percent breakthrough. The percent of cesium removed by the resin at the onset of breakthrough was 99.96. The elution of cesium with 0… more
Date: August 24, 2004
Creator: ADU-WUSU, KOFI
Partner: UNT Libraries Government Documents Department
open access

EFFECTS OF XE ION IRRADIATION AND SUBSEQUENT ANNEALING ON THE PROPERTIES OF MAGNESIUM-ALUMINATE SPINEL

Description: Single crystals of magnesium-aluminate spinel MgAl{sub 2}O{sub 4} were irradiated with 340 keV Xe{sup 2} ions at {minus}173 C ({approximately} 100 K). A fluence of 1 x 10{sup 20} Xe/m{sup 2} created an amorphous layer at the surface of the samples. The samples were annealed for 1 h at different temperatures ranging from 130 C to 880 C. Recrystallization took place in the temperature interval between 610 C and 855 C. Transmission electron microscopy (TEM) images show two distinct layers near the… more
Date: April 1, 2000
Creator: AFANASYEV, I. & AL, ET
Partner: UNT Libraries Government Documents Department
Back to Top of Screen