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REMOVING SLUDGE HEELS FROM SAVANNAH RIVER SITE WASTE TANKS BY OXALIC ACID DISSOLUTION (open access)

REMOVING SLUDGE HEELS FROM SAVANNAH RIVER SITE WASTE TANKS BY OXALIC ACID DISSOLUTION

The Savannah River Site (SRS) will remove sludge as part of waste tank closure operations. Typically the bulk sludge is removed by mixing it with supernate to produce a slurry, and transporting the slurry to a downstream tank for processing. Experience shows that a residual heel may remain in the tank that cannot be removed by this conventional technique. In the past, SRS used oxalic acid solutions to disperse or dissolve the sludge heel to complete the waste removal. To better understand the actual conditions of oxalic acid cleaning of waste from carbon steel tanks, the authors developed and conducted an experimental program to determine its effectiveness in dissolving sludge, the hydrogen generation rate, the generation rate of other gases, the carbon steel corrosion rate, the impact of mixing on chemical cleaning, the impact of temperature, and the types of precipitates formed during the neutralization process. The test samples included actual SRS sludge and simulated SRS sludge. The authors performed the simulated waste tests at 25, 50, and 75 C by adding 8 wt % oxalic acid to the sludge over seven days. They conducted the actual waste tests at 50 and 75 C by adding 8 wt % oxalic …
Date: March 1, 2009
Creator: Poirier, M; David Herman, D; Fernando Fondeur, F; John Pareizs, J; Michael Hay, M; Bruce Wiersma, B et al.
System: The UNT Digital Library
DEVELOPMENT OF A CROSSFLOW FILTER TO REMOVE SOLIDS FROM RADIOACTIVE LIQUID WASTE: COMPARISON OF TEST DATA WITH OPERATING EXPERIENCE - 9119 (open access)

DEVELOPMENT OF A CROSSFLOW FILTER TO REMOVE SOLIDS FROM RADIOACTIVE LIQUID WASTE: COMPARISON OF TEST DATA WITH OPERATING EXPERIENCE - 9119

In 2008, the Savannah River Site (SRS) began treatment of liquid radioactive waste from its Tank Farms. To treat waste streams containing {sup 137}Cs, {sup 90}Sr, and actinides, SRS developed the Actinide Removal Process (ARP) and the Modular Caustic Side Solvent Extraction Unit (MCU). The Actinide Removal Process contacts the waste with monosodium titanate (MST) to sorb strontium and select actinides. After MST contact, the process filters the resulting slurry to remove the MST (with sorbed strontium and actinides) and any entrained sludge. The filtrate is transported to the MCU to remove cesium. The solid particle removed by the filter are concentrated to {approx} 5 wt %, washed to reduce the concentration of dissolved sodium, and transported to the Defense Waste Processing Facility (DWPF) for vitrification. The authors conducted tests with 0.5 {micro} and 0.1 {micro} Mott sintered stainless steel crossflow filter at bench-scale (0.19 ft{sup 2} surface area) and pilot-scale (11.2 ft{sup 2}). The collected data supported design of the filter for the process and identified preferred operating conditions for the full-scale process (230 ft{sup 2}). The testing investigated the influence of operating parameters, such as filter pore size, axial velocity, transmembrane pressure, and solids loading, on filter flux, …
Date: March 1, 2009
Creator: Poirier, M; David Herman, D; Samuel Fink, S & Julius Lacerna, J
System: The UNT Digital Library
Task 1: Steam Oxidation,” (open access)

Task 1: Steam Oxidation,”

Need to improve efficiency, decrease emissions (esp. CO2) associated with the continued use of coal for power generation
Date: March 1, 2009
Creator: Wright, I. G. & Holcomb, G. R.
System: The UNT Digital Library
Task 2: Materials for Oxy-Combustion Systems, (open access)

Task 2: Materials for Oxy-Combustion Systems,

Modeling of oxy-combustion environments based on different strategies
Date: March 1, 2009
Creator: Holcomb, G. R.; Shim, H.-S.; Meier, G. & Natesan, K.
System: The UNT Digital Library
Progress Update,” NETL CO2 Capture Technology for Existing Plants (open access)

Progress Update,” NETL CO2 Capture Technology for Existing Plants

Progress Update,” NETL CO2 Capture Technology for Existing Plants
Date: March 1, 2009
Creator: Holcomb, D. Huckaby and G. R.
System: The UNT Digital Library
A search for muon neutrino and antineutrino disappearance in MiniBooNE (open access)

A search for muon neutrino and antineutrino disappearance in MiniBooNE

The MiniBooNE Collaboration reports a search for {nu}{sub {mu}} and {bar {nu}}{sub {mu}} disappearance in the {Delta}m{sup 2} region of a few eV{sup 2}. These measurements are important for constraining models with extra types of neutrinos, extra dimensions and CPT violation. Fits to the shape of the {nu}{sub {mu}} and {bar {nu}}{sub {mu}} energy spectra reveal no evidence for disappearance at 90% confidence level (CL) in either mode. This is the first test of {bar {nu}}{sub {mu}} disappearance between {Delta}m{sup 2} = 0.1-10 eV{sup 2}.
Date: March 1, 2009
Creator: Aguilar-Arevalo, Alexis A.; Anderson, C. E.; Bazarko, A. O.; Brice, S. J.; Brown, Bruce C.; Bugel, Leonard G. et al.
System: The UNT Digital Library
Measurement of the b-Hadron Production Cross Section Using Decays to MU- d0 X Final States in p anti-p Collisions at s**(1/2) = 1.96-TeV (open access)

Measurement of the b-Hadron Production Cross Section Using Decays to MU- d0 X Final States in p anti-p Collisions at s**(1/2) = 1.96-TeV

We report a measurement of the production cross section for b hadrons in p{bar p} collisions at {radical}s = 1.96 TeV. Using a data sample derived from an integrated luminosity 83 pb{sup -1} collected with the upgraded Collider Detector (CDF II) at the Fermilab Tevatron, we analyze b hadrons, H{sub b}, partially reconstructed in the semileptonic decay mode H{sub b} {yields} {mu}{sup -} D{sup 0} X. Our measurement of the inclusive production cross section for b hadrons with transverse momentum p{sub T} > 9 GeV/c and rapidity |y| < 0.6 is {sigma} = 1.30 {micro}b {+-} 0.05 {micro}b(stat) {+-} 0.14 {micro}b(syst) {+-} 0.07 {micro}b({Beta}), where the uncertainties are statistical, systematic, and from branching fractions respectively. The differential cross sections d{sigma}/d{sub T}T are found to be in good agreement with recent measurements of the H{sub b} cross section and well described by fixed-order next-to-leading logarithm predictions.
Date: March 1, 2009
Creator: Aaltonen, T.; Adelman, Jahred A.; Akimoto, T.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, Dante E. et al.
System: The UNT Digital Library
The Underground Corrosion of Selected Type 300 Stainless Steels After 34 Years (open access)

The Underground Corrosion of Selected Type 300 Stainless Steels After 34 Years

Recently, interest in long-term underground corrosion has greatly increased because of the ongoing need to dispose of nuclear waste. Additionally, the Nuclear Waste Policy Act of 1982 requires disposal of high-level nuclear waste in an underground repository. Current contaminant release and transport models use limited available short-term underground corrosion rates when considering container and waste form degradation. Consequently, the resulting models oversimplify the complex mechanisms of underground metal corrosion. The complexity of stainless steel corrosion mechanisms and the processes by which corrosion products migrate from their source are not well depicted by a corrosion rate based on general attack. The research presented here is the analysis of austenitic stainless steels after 33½ years of burial. In this research, the corrosion specimens were analyzed using applicable ASTM standards as well as microscopic and X-ray examination to determine the mechanisms of underground stainless steel corrosion. As presented, the differences in the corrosion mechanisms vary with the type of stainless steel and the treatment of the samples. The uniqueness of the long sampling time allows for further understanding of the actual stainless steel corrosion mechanisms, and when applied back into predictive models, will assist in reduction of the uncertainty in parameters for predicting …
Date: March 1, 2009
Creator: Yoder, T. S. & Flitton, M. K. Adler
System: The UNT Digital Library
Developing microbe-plant interactions for applications in plant-growth promotion and disease control, production of useful compounds, remediation, and carbon sequestration (open access)

Developing microbe-plant interactions for applications in plant-growth promotion and disease control, production of useful compounds, remediation, and carbon sequestration

Interactions between plants and microbes are an integral part of our terrestrial ecosystem. Microbe-plant interactions are being applied in many areas. In this review, we present recent reports of applications in the areas of plant-growth promotion, biocontrol, bioactive compound and biomaterial production, remediation and carbon sequestration. Challenges, limitations and future outlook for each field are discussed.
Date: March 1, 2009
Creator: Wu, C. H.; Bernard, S.; Andersen, G.L. & Chen, W.
System: The UNT Digital Library
Bioaccumulation Potential Of Air Contaminants: Combining Biological Allometry, Chemical Equilibrium And Mass-Balances To Predict Accumulation Of Air Pollutants In Various Mammals (open access)

Bioaccumulation Potential Of Air Contaminants: Combining Biological Allometry, Chemical Equilibrium And Mass-Balances To Predict Accumulation Of Air Pollutants In Various Mammals

In the present study we develop and test a uniform model intended for single compartment analysis in the context of human and environmental risk assessment of airborne contaminants. The new aspects of the model are the integration of biological allometry with fugacity-based mass-balance theory to describe exchange of contaminants with air. The developed model is applicable to various mammalian species and a range of chemicals, while requiring few and typically well-known input parameters, such as the adult mass and composition of the species, and the octanol-water and air-water partition coefficient of the chemical. Accumulation of organic chemicals is typically considered to be a function of the chemical affinity forlipid components in tissues. Here, we use a generic description of chemical affinity for neutral and polar lipids and proteins to estimate blood-air partition coefficients (Kba) and tissue-air partition coefficients (Kta) for various mammals. This provides a more accurate prediction of blood-air partition coefficients, as proteins make up a large fraction of total blood components. The results show that 75percent of the modeled inhalation and exhalation rate constants are within a factor of 2 from independent empirical values for humans, rats and mice, and 87percent of the predicted blood-air partition coefficients are …
Date: March 1, 2009
Creator: Veltman, Karin; McKone, Thomas E.; Huijbregts, Mark A.J. & Hendriks, A. Jan
System: The UNT Digital Library
Study of the decay K+ ---> pi+ nu anti-nu in the momentum region 140 < P(pi) < 199-MeV/c (open access)

Study of the decay K+ ---> pi+ nu anti-nu in the momentum region 140 < P(pi) < 199-MeV/c

None
Date: March 1, 2009
Creator: Artamonov, A. V.; /Serpukhov, IHEP; Bassalleck, B.; U., /New Mexico; Bhuyan, B.; /Brookhaven et al.
System: The UNT Digital Library
Update on Fresh Fuel Characterization of U-Mo Alloys (open access)

Update on Fresh Fuel Characterization of U-Mo Alloys

The need to provide more accurate property information on U-Mo fuel alloys to operators, modellers, researchers, fabricators, and government increases as success of the GTRI Reactor Convert program continues. This presentation provides an update on fresh fuel characterization activities that have occurred at the INL since the RERTR 2008 conference in Washington, D.C. The update is particularly focused on properties recently obtained and on the development progress of new measurement techniques. Furthermore, areas where useful and necessary information is still lacking is discussed. The update deals with mechanical, physical, and microstructural properties for both integrated and separate effects. Appropriate discussion of fabrication characteristics, impurities, thermodynamic response, and effects on the topic areas are provided, along with a background on the characterization techniques used and developed to obtain the information. Efforts to measure similar characteristics on irradiated fuel plates are discussed.
Date: March 1, 2009
Creator: Burkes, D. E.; Wachs, D. M.; Keiser, D. D.; Okuniewski, M. A.; Jue, J. F.; Rice, F. J. et al.
System: The UNT Digital Library
Quantitative and qualitative measures of decomposition: Is there a link? (open access)

Quantitative and qualitative measures of decomposition: Is there a link?

Decomposition rates of loblolly pine coarse woody debris (CWD) were determined by mass loss and wood density changes for trees that differed in source of mortality (natural, girdle-poison, and felling). Specifically, three treatments were examined: (1) control (CON): natural mortality; (2) CD: 5-fold increase in CWD compared with the CON; and (3) CS: 12-fold increase in snags compared with the CON. The additional CWD in the CD treatment plots and the additional snags in the CS plots were achieved by felling (for the CD plots) or girdling followed by herbicide injection (for the CS plots) select trees in these plots. Consequently,mortality on the CD plots is due to natural causes and felling. Likewise, mortality on the CS plots is due to natural causes and girdle-poison. In each treatment plot, mortality due to natural causes was inventoried since 1997, whereas mortality due to girdle-poison and felling were inventoried since 2001. No significant difference was detected between the rates of decomposition for the CWD on these treatment plots, indicating that source of the tree mortality did not influence rates of decomposition once the tree fell. These experimental measures of decomposition were compared with two decay classification systems (three- and five-unit classifications) to …
Date: March 1, 2009
Creator: Eaton, Robert, J. & Sanchez, Felipe, G.
System: The UNT Digital Library
Search for narrow resonances lighter than Upsilon mesons (open access)

Search for narrow resonances lighter than Upsilon mesons

We report a search for narrow resonances, produced in p{bar p} collisions at {radical}s = 1.96 TeV, that decay into muon pairs with invariant mass between 6.3 and 9.0 GeV/c{sup 2}. The data, collected with the CDF II detector at the Fermilab Tevatron collider, correspond to an integrated luminosity of 630 pb{sup -1}. We use the dimuon invariant mass distribution to set 90% upper credible limits of about 1% to the ratio of the production cross section times muonic branching fraction of possible narrow resonances to that of the {Upsilon}(1S) meson.
Date: March 1, 2009
Creator: Aaltonen, T.; Adelman, Jahred A.; Akimoto, T.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, Dante E. et al.
System: The UNT Digital Library
The lightness of being: mass, ether, and unification of the forces (open access)

The lightness of being: mass, ether, and unification of the forces

How can an electron be both a wave and a particle? At the same time? Because it is a quantum field. That key insight seems to be underappreciated, given the awe and mysticism that permeate most nontechnical discussions of modern physics. Perhaps the root of the problem is that most popularizations of quantum mechanics and of particle physics shy away from quantized fields, the natural language for microscopic phenomena. In 'The Lightness of Being: Mass, Ether, and the Unification of Forces', Frank Wilczek confronts quantum field theory head on, demystifying not only wave-particle duality but also the origin of mass for hadrons (that is, everyday matter). Wilczek is the Herman Feshbach Professor of Physics at MIT and a co-recipient of the 2004 Nobel Prize in Physics. His research has spanned almost all aspects of theoretical particle physics, with significant forays into condensed-matter physics and dense nuclear matter (condensed quark matter, one might say). Recurring themes are the richness of quantum chromodynamics (QCD) and the alluring ideas of unification. His breadth and depth make him a sought after speaker for colloquia and public lectures. Wilczek also contributes an occasional Reference Frame column to 'Physics Today'. The material in 'The Lightness of …
Date: March 1, 2009
Creator: Kronfeld, Andreas S.
System: The UNT Digital Library
CKow -- A More Transparent and Reliable Model for Chemical Transfer to Meat and Milk (open access)

CKow -- A More Transparent and Reliable Model for Chemical Transfer to Meat and Milk

The objective of this study is to increase the understanding and transparency of chemical biotransfer modeling into meat and milk and explicitly confront the uncertainties in exposure assessments of chemicals that require such estimates. In cumulative exposure assessments that include food pathways, much of the overall uncertainty is attributable to the estimation of transfer into biota and through food webs. Currently, the most commonly used meat and milk-biotransfer models date back two decades and, in spite of their widespread use in multimedia exposure models few attempts have been made to advance or improve the outdated and highly uncertain Kow regressions used in these models. Furthermore, in the range of Kow where meat and milk become the dominant human exposure pathways, these models often provide unrealistic rates and do not reflect properly the transfer dynamics. To address these issues, we developed a dynamic three-compartment cow model (called CKow), distinguishing lactating and non-lactating cows. For chemicals without available overall removal rates in the cow, a correlation is derived from measured values reported in the literature to predict this parameter from Kow. Results on carry over rates (COR) and biotransfer factors (BTF) demonstrate that a steady-state ratio between animal intake and meat concentrations …
Date: March 1, 2009
Creator: Rosenbaum, Ralph K.; McKone, Thomas E. & Jolliet, Olivier
System: The UNT Digital Library
Observation of Single Top Quark Production (open access)

Observation of Single Top Quark Production

We report first observation of the electroweak production of single top quarks in p{bar p} collisions at {radical}s = 1.96 TeV based on 2.3 fb{sup ?1} of data collected by the D0 detector at the Fermilab Tevatron Collider. Using events containing an isolated electron or muon and missing transverse energy, together with jets originating from the fragmentation of b quarks, we measure a cross section of {sigma}(p{bar p} {yields} tb + X, tqb + X) = 3.94 {+-} 0.88 pb. The probability to measure a cross section at this value or higher in the absence of signal is 2.5 x 10{sup ?7}, corresponding to a 5.0 standard deviation significance for the observation.
Date: March 1, 2009
Creator: Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, Bannanje Sripath; Adams, M.; Adams, T. et al.
System: The UNT Digital Library
A Measurement of the t anti-t Cross Section in p anti-p Collisions at s**(1/2) = 1.96-TeV using Dilepton Events with a Lepton plus Track Selection (open access)

A Measurement of the t anti-t Cross Section in p anti-p Collisions at s**(1/2) = 1.96-TeV using Dilepton Events with a Lepton plus Track Selection

This paper reports a measurement of the cross section for the pair production of top quarks in p{bar p} collisions at {radical}s = 1.96 TeV at the Fermilab Tevatron. The data was collected from the CDF II detector in a set of runs with a total integrated luminosity of 1.1 fb{sup -1}. The cross section is measured in the dilepton channel, the subset of t{bar t} events in which both top quarks decay through t {yields} Wb {yields} {ell}{nu}b, where {ell} = e, {mu}, or {tau}. The lepton pair is reconstructed as one identified electron or muon and one isolated track. The use of an isolated track to identify the second lepton increases the t{bar t} acceptance, particularly for the case in which one W decays as W {yields} {tau}{nu}. The purity of the sample may be further improved at the cost of a reduction in the number of signal events, by requiring an identified b-jet. They present the results of measurements performed with and without the request of an identified b-jet. the former is the first published CDF result for which a b-jet requirement is added to the dilepton selection. In the CDF data there are 129 pretag lepton …
Date: March 1, 2009
Creator: Aaltonen, T.; Phys., /Helsinki Inst. of; Adelman, Jahred A.; /Chicago U., EFI; Akimoto, T.; U., /Tsukuba et al.
System: The UNT Digital Library
Microbial co-habitation and lateral gene transfer: what transposases can tell us (open access)

Microbial co-habitation and lateral gene transfer: what transposases can tell us

Determining the habitat range for various microbes is not a simple, straightforward matter, as habitats interlace, microbes move between habitats, and microbial communities change over time. In this study, we explore an approach using the history of lateral gene transfer recorded in microbial genomes to begin to answer two key questions: where have you been and who have you been with? All currently sequenced microbial genomes were surveyed to identify pairs of taxa that share a transposase that is likely to have been acquired through lateral gene transfer. A microbial interaction network including almost 800 organisms was then derived from these connections. Although the majority of the connections are between closely related organisms with the same or overlapping habitat assignments, numerous examples were found of cross-habitat and cross-phylum connections. We present a large-scale study of the distributions of transposases across phylogeny and habitat, and find a significant correlation between habitat and transposase connections. We observed cases where phylogenetic boundaries are traversed, especially when organisms share habitats; this suggests that the potential exists for genetic material to move laterally between diverse groups via bridging connections. The results presented here also suggest that the complex dynamics of microbial ecology may be traceable …
Date: March 1, 2009
Creator: Hooper, Sean D.; Mavromatis, Konstantinos & Kyrpides, Nikos C.
System: The UNT Digital Library
Lenses in the forest: cross--correlation of the Lyman-alpha flux with CMB lensing (open access)

Lenses in the forest: cross--correlation of the Lyman-alpha flux with CMB lensing

We present a theoretical estimate for a new observable: the cross-correlation between the Lyman-{alpha}-flux fluctuations in quasar (QSO) spectra and the convergence of the cosmic microwave background (CMB) as measured along the same line-of-sight. As a first step toward the assessment of its detectability, we estimate the signal-to-noise ratio using linear theory. Although the signal-to-noise is small for a single line-of-sight and peaks at somewhat smaller redshifts than those probed by the Lyman-{alpha} forest, we estimate a total signal-to-noise of 9 for cross-correlating QSO spectra of SDSSIII with Planck and 20 for cross-correlating with a future polarization based CMB experiment. The detection of this effect would be a direct measure of the neutral hydrogen-matter cross-correlation and could provide important information on the growth of structures at large scales in a redshift range which is still poorly probed by observations.
Date: March 1, 2009
Creator: Vallinotto, Alberto; /Paris, Inst. Astrophys. /Fermilab; Das, Sudeep; U., /Princeton U. Observ. /Princeton; Spergel, David N.; /Princeton U. Observ. /APC, Paris et al.
System: The UNT Digital Library
Hydraulic properties of adsorbed water films in unsaturated porous media (open access)

Hydraulic properties of adsorbed water films in unsaturated porous media

Adsorbed water films strongly influence residual water saturations and hydraulic conductivities in porous media at low saturations. Hydraulic properties of adsorbed water films in unsaturated porous media were investigated through combining Langmuir's film model with scaling analysis, without use of any adjustable parameters. Diffuse double layer influences are predicted to be important through the strong dependence of adsorbed water film thickness (f) on matric potential ({Psi}) and ion charge (z). Film thickness, film velocity, and unsaturated hydraulic conductivity are predicted to vary with z{sup -1}, z{sup -2}, and z{sup -3}, respectively. In monodisperse granular media, the characteristic grain size ({lambda}) controls film hydraulics through {lambda}{sup -1} scaling of (1) the perimeter length per unit cross sectional area over which films occur, (2) the critical matric potential ({Psi}{sub c}) below which films control flow, and (3) the magnitude of the unsaturated hydraulic conductivity when {Psi} &lt; {Psi}{sub c}. While it is recognized that finer textured sediments have higher unsaturated hydraulic conductivities than coarser sands at intermediate {Psi}, the {lambda}{sup -1} scaling of hydraulic conductivity predicted here extends this understanding to very low saturations where all pores are drained. Extremely low unsaturated hydraulic conductivities are predicted under adsorbed film-controlled conditions (generally &lt; …
Date: March 1, 2009
Creator: Tokunaga, Tetsu K.
System: The UNT Digital Library
Simulation in the Service of Design - Asking the Right Questions (open access)

Simulation in the Service of Design - Asking the Right Questions

This paper proposes an approach to the creation of design tools that address the real information needs of designers in the early stages of design of nonresidential buildings. Traditional simplified design tools are typically too limited to be of much use, even in conceptual design. The proposal is to provide access to the power of detailed simulation tools, at a stage in design when little is known about the final building, but at a stage also when the freedom to explore options is greatest. The proposed approach to tool design has been derived from consultation with design analysis teams as part of the COMFEN tool development. The paper explores how tools like COMFEN have been shaped by this consultation and how requests from these teams for real-world relevance might shape such tools in the future, drawing into the simulation process the lessons from Post Occupancy Evaluation (POE) of buildings.
Date: March 1, 2009
Creator: Donn, Michael; Selkowitz, Stephen & Bordass, Bill
System: The UNT Digital Library
The U-tube sampling methodology and real-time analysis of geofluids (open access)

The U-tube sampling methodology and real-time analysis of geofluids

The U-tube geochemical sampling methodology, an extension of the porous cup technique proposed by Wood [1973], provides minimally contaminated aliquots of multiphase fluids from deep reservoirs and allows for accurate determination of dissolved gas composition. The initial deployment of the U-tube during the Frio Brine Pilot CO{sub 2} storage experiment, Liberty County, Texas, obtained representative samples of brine and supercritical CO{sub 2} from a depth of 1.5 km. A quadrupole mass spectrometer provided real-time analysis of dissolved gas composition. Since the initial demonstration, the U-tube has been deployed for (1) sampling of fluids down gradient of the proposed Yucca Mountain High-Level Waste Repository, Armagosa Valley, Nevada (2) acquiring fluid samples beneath permafrost in Nunuvut Territory, Canada, and (3) at a CO{sub 2} storage demonstration project within a depleted gas reservoir, Otway Basin, Victoria, Australia. The addition of in-line high-pressure pH and EC sensors allows for continuous monitoring of fluid during sample collection. Difficulties have arisen during U-tube sampling, such as blockage of sample lines from naturally occurring waxes or from freezing conditions; however, workarounds such as solvent flushing or heating have been used to address these problems. The U-tube methodology has proven to be robust, and with careful consideration of …
Date: March 1, 2009
Creator: Freifeld, Barry; Perkins, Ernie; Underschultz, James & Boreham, Chris
System: The UNT Digital Library
Measurements of differential cross sections of Z/gamma*+jets+X events in proton anti-proton collisions at s**(1/2) = 1.96-TeV (open access)

Measurements of differential cross sections of Z/gamma*+jets+X events in proton anti-proton collisions at s**(1/2) = 1.96-TeV

We present cross section measurements for Z/{gamma}* + jets + X production, differential in the transverse momenta of the three leading jets. The data sample was collected with the D0 detector at the Fermilab Tevatron p{bar p} collider at a center-of-mass energy of 1.96 TeV and corresponds to an integrated luminosity of 1 fb{sup -1}. Leading and next-to-leading order perturbative QCD predictions are compared with the measurements, and agreement is found within the theoretical and experimental uncertainties. We also make comparisons with the predictions of four event generators. Two parton-shower-based generators show significant shape and normalization differences with respect to the data. In contrast, two generators combining tree-level matrix elements with a parton shower give a reasonable description of the shapes observed in data, but the predicted normalizations show significant differences with respect to the data, reflecting large scale uncertainties. For specific choices of scales, the normalizations for either generator can be made to agree with the measurements.
Date: March 1, 2009
Creator: Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, Bannanje Sripath; Adams, M.; Adams, T. et al.
System: The UNT Digital Library