Resource Type

States

Multivariate searches for single top quark production with the D0 detector (open access)

Multivariate searches for single top quark production with the D0 detector

We present a search for electroweak production of single top quarks in (p{bar p} {yields} t{bar b} + X) and t-channel (p{bar p} {yields} tq{bar b} + X) modes. We have analyzed 230 pb{sup -1} of data collected with the D0 detector at the Fermilab Tevatron collider at a center-of-mass energy of {radical}s = 1.96 TeV. Two separate analysis methods are used: neural networks and a cut-based analysis. No evidence for a single top quark signal is found. We set 95% confidence level upper limits on the production cross sections using Bayesian statistics, based on event counts and binned likelihoods formed from the neural network output. The limits from the neural network (cut-based) analysis are 6.4 pb (10.6 pb) in the s-channel and 5.0 pb (11.3 pb) in the t-channel.
Date: April 1, 2006
Creator: Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
System: The UNT Digital Library
A Precise measurement of the B0(s) lifetime (open access)

A Precise measurement of the B0(s) lifetime

The authors report a measurement of the B{sub s}{sup 0} lifetime in the semileptonic decay channel B{sub s}{sup 0} {yields} D{sub s}{sup -}{mu}{sup +}{nu}X (and its charge conjugate), using approximately 0.4 fb{sup -1} of data collected with the D0 detector during 2002-2004. They have reconstructed 5176 D{sub s}{sup -} {mu}{sup +} signal events, where the D{sub s}{sup -} is identified via the decay D{sub s}{sup 0} {yields} {phi}{pi}{sup -}, followed by {phi} {yields} K{sup +}K{sup -}. Using these events, they have measured the B{sub s}{sup 0} lifetime to be {tau}(B{sub s}{sup 0}) = 1.398 {+-} 0.044 (stat){sub -0.025}{sup +0.028}(syst) ps. This is the most precise measurement of the B{sub s}{sup 0} lifetime to date.
Date: April 1, 2006
Creator: Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
System: The UNT Digital Library
Search for excited muons in p anti-p collisions at s**(1/2) = 1.96- TeV (open access)

Search for excited muons in p anti-p collisions at s**(1/2) = 1.96- TeV

We present the results of a search for the production of an excited state of the muon, {mu}*, in proton antiproton collisions at {radical}s = 1.96 TeV. The data have been collected with the D0 experiment at the Fermilab Tevatron Collider and correspond to an integrated luminosity of approximately 380 pb{sup -1}. We search for {mu}* in the process p{bar p} {yields} {mu}*{nu}, with the {mu}* subsequently decaying to a muon plus photon. No excess above the standard model expectation is observed in data. Interpreting our data in the context of a model that describes {mu}* production by four-fermion contact interactions and {mu}* decay via electroweak processes, we exclude production cross sections higher than 0.057 pb-0.112 pb at the 95% confidence level, depending on the mass of the excited muon. Choosing the scale for contact interactions to be {Lambda} = 1 TeV, excited muon masses below 618 GeV are excluded.
Date: April 1, 2006
Creator: Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
System: The UNT Digital Library
Measurement of direct photon emission in the K(L) ---> pi+ pi- gamma decay mode (open access)

Measurement of direct photon emission in the K(L) ---> pi+ pi- gamma decay mode

In this paper the KTeV collaboration reports the analysis of 112.1 x 10{sup 3} candidate K{sub L} {yields} {pi}{sup +}{pi}{sup -}{gamma} decays including a background of 671 {+-} 41 events with the objective of determining the photon production mechanisms intrinsic to the decay process. These decays have been analyzed to extract the relative contributions of the Cp violating bremsstrahlung process and the CP conserving M1 and CP violating E1 direct photon emission processes. The M1 direct photon emission amplitude and its associated vector form factor parameterized as |{bar g}{sub M1}|(1 + a{sub 1}/a{sub 2}/(M{sub {rho}}{sup 2}-M{sub K}{sup 2}) + 2M{sub K}E{sub {gamma}}) have been measured to be |{bar g}{sub M1}| = 1.198 {+-} 0.035(stat) {+-} 0.086(syst) and a{sub 1}/a{sub 2} = =0.738 {+-} 0.007(stat) {+-} 0.018(syst) GeV{sup 2}/c{sup 2} respectively. An upper limit for the CP violating E1 direct emission amplitude |g{sub E1}| {le} 0.1 (90%CL) has been found. The overall ratio of direct photon emission (DE) to total photon emission including the bremsstrahlung process (IB) has been determined to be DE/(DE + IB) = 0.689 {+-} 0.021 for E{sub {gamma}} {ge} 20 MeV.
Date: April 1, 2006
Creator: Abouzaid, E.; Arenton, M.; Barker, A. R.; Bellantoni, L.; Bellavance, A.; Blucher, E. et al.
System: The UNT Digital Library
Air to Muscle and Blood/Plasma to Muscle Distribution of Volatile Organic Compounds and Drugs: Linear Free Energy Analyses (open access)

Air to Muscle and Blood/Plasma to Muscle Distribution of Volatile Organic Compounds and Drugs: Linear Free Energy Analyses

Article on air to muscle and blood/plasma to muscle distribution of volatile organic compounds and drugs and linear free energy analyses.
Date: April 20, 2006
Creator: Abraham, M. H. (Michael H.); Ibrahim, Adam & Acree, William E. (William Eugene)
System: The UNT Digital Library
Search for Large Extra Dimensions in the Production of Jets and Missing Transverse Energy in ppbar Collisions at s**(1/2) = 1.96 TeV (open access)

Search for Large Extra Dimensions in the Production of Jets and Missing Transverse Energy in ppbar Collisions at s**(1/2) = 1.96 TeV

The authors present the results of a search for new physics in the jets plus missing transverse energy data sample collected from 368 pb{sup -1} of p{bar p} collisions at {radical}s = 1.96 TeV recorded by the Collider Detector at Fermilab. They compare the number of events observed in the data with a data-based estimate of the standard model backgrounds contributing to this signature. They observe no significant excess of events, and they interpret this null result in terms of lower limits on the fundamental Planck scale for a large extra dimensions scenario.
Date: April 1, 2006
Creator: Abulencia, A.; Acosta, D.; Adelman, Jahred A.; Affolder, T.; Akimoto, T.; Albrow, M.G. et al.
System: The UNT Digital Library
Separation of Carbon Dioxide from Flue Gas Using Ion Pumping (open access)

Separation of Carbon Dioxide from Flue Gas Using Ion Pumping

We are developing a new way of separating carbon dioxide from flue gas based on ionic pumping of carbonate ions dissolved in water. Instead of relying on large temperature or pressure changes to remove carbon dioxide from solvent used to absorb it from flue gas, the ion pump increases the concentration of dissolved carbonate ion in solution. This increases the overlying vapor pressure of carbon dioxide gas, which can be removed from the downstream side of the ion pump as a nearly pure gas. This novel approach to increasing the concentration of the extracted gas permits new approaches to treating flue gas. The slightly basic water used as the extraction medium is impervious to trace acid gases that destroy existing solvents, and no pre-separation is necessary. The simple, robust nature of the process lends itself to small separation plants. Although the energy cost of the ion pump is significant, we anticipate that it will be compete favorably with the current 35% energy penalty of chemical stripping systems in use at power plants. There is the distinct possibility that this simple method could be significantly more efficient than existing processes.
Date: April 21, 2006
Creator: Aines, R.; Bourcier, W. L. & Johnson, M. R.
System: The UNT Digital Library
Renewal, Modulation, and Superstatistics in Times Series (open access)

Renewal, Modulation, and Superstatistics in Times Series

Article discussing two different approaches, referred to as renewal and modulation, to generate time series with a nonexponential distribution of waiting times.
Date: April 27, 2006
Creator: Allegrini, Paolo; Barbi, Francesco; Grigolini, Paolo & Paradisi, Paolo
System: The UNT Digital Library
Charm Spectroscopy at BaBar (open access)

Charm Spectroscopy at BaBar

In this note we present results on charmed hadron decays recently obtained from data recorded with the BABAR detector at the Stanford Linear Accelerator Center (SLAC) PEP-II B-Factory.
Date: April 21, 2006
Creator: Altenburg, D. & U., /Dortmund
System: The UNT Digital Library
Plasma Biasing to Control the Growth Conditions of Diamond-Like Carbon (open access)

Plasma Biasing to Control the Growth Conditions of Diamond-Like Carbon

It is well known that the structure and properties ofdiamond-like carbon, and in particular the sp3/sp2 ratio, can becontrolled by the energy of the condensing carbon ions or atoms. In manypractical cases, the energy of ions arriving at the surface of thegrowing film is determined by the bias applied to the substrate. The biascauses a sheath to form between substrate and plasma in which thepotential difference between plasma potential and surface potentialdrops. In this contribution, we demonstrate that the same results can beobtained with grounded substrates by shifting the plasma potential. This"plasma biasing" (as opposed to "substrate biasing") is shown to workwell with pulsed cathodic carbon arcs, resulting in tetrahedral amorphouscarbon (ta-C) films that are comparable to the films obtained with theconventional substrate bias. To verify the plasma bias approach, ta-Cfilms were deposited by both conventional and plasma bias andcharacterized by transmission electron microscopy (TEM) and electronenergy loss spectrometry (EELS). Detailed data for comparison of thesefilms are provided.
Date: April 30, 2006
Creator: Anders, Andre; Pasaja, Nitisak; Lim, Sunnie H.N.; Petersen, TimC. & Keast, Vicki J.
System: The UNT Digital Library
Analysis of Residential System Strategies Targeting Least-Cost Solutions Leading to Net Zero Energy Homes: Preprint (open access)

Analysis of Residential System Strategies Targeting Least-Cost Solutions Leading to Net Zero Energy Homes: Preprint

The U. S. Department of Energy's Building America residential systems research project uses an analysis-based system research approach to identify research priorities, identify technology gaps and opportunities, establish a consistent basis to track research progress, and identify system solutions that are most likely to succeed as the initial targets for residential system research projects. This report describes the analysis approach used by the program to determine the most cost-effective pathways to achieve whole-house energy-savings goals. This report also provides an overview of design/technology strategies leading to net zero energy buildings as the basis for analysis of future residential system performance.
Date: April 1, 2006
Creator: Anderson, R.; Christensen, C. & Horowitz, S.
System: The UNT Digital Library
Seismic Design and Retrofit of Equipment and Piping (open access)

Seismic Design and Retrofit of Equipment and Piping

None
Date: April 19, 2006
Creator: Antaki, George
System: The UNT Digital Library
Integrity of Pipes and Vessels Subject to Internal Explosions: an overview (open access)

Integrity of Pipes and Vessels Subject to Internal Explosions: an overview

None
Date: April 19, 2006
Creator: Antaki, George; McKeel, Charles & Pease, Derrick
System: The UNT Digital Library
Developments in Realistic Design for Aperiodic Mo/Si Multilayermirrors (open access)

Developments in Realistic Design for Aperiodic Mo/Si Multilayermirrors

Aperiodic multilayers have been designed for various applications, using numeric algorithms and analytical solutions, for many years with varying levels of success. This work developed a more realistic model for simulating aperiodic Mo/Si multilayers to be used in these algorithms by including the formation of MoSi{sub 2}. Using a genetic computer code we were able to optimize a 45{sup o} multilayer for a large bandpass reflection multilayer that gave good agreement with the model.
Date: April 5, 2006
Creator: Aquila, A. L.; Salmassi, F.; Dollar, F.; Liu, Y. & Gullikson, E. M.
System: The UNT Digital Library
Anisotropic x-ray magnetic linear dichroism at the Fe L2,3 edgesin Fe3O4 (open access)

Anisotropic x-ray magnetic linear dichroism at the Fe L2,3 edgesin Fe3O4

X-ray magnetic linear dichroism at the Fe L{sub 2,3} edges of the ferrimagnet Fe{sub 3}O{sub 4} was found to exhibit a strong dependence on the relative orientation of external magnetic field, x-ray polarization, and crystalline axes. Spectral shape and magnitude of the effect were determined for Fe{sub 3}O{sub 4}(011) and Fe{sub 3}O{sub 4}(001) thin films varying the in-plane orientation of field and polarization. All dichroism spectra can be described as a linear combination of three fundamental spectra which in turn give a good agreement with calculated spectra using atomic multiplet theory. The angular dependence of the magnetic dichroism reflects the crystal field symmetry. It can be used to estimate the crystal field splitting and allows determining the spin quantization axis.
Date: April 30, 2006
Creator: Arenholz, Elke; van der Laan, Gerrit; Chopdekar, Rajesh V. & Suzuki, Yuri
System: The UNT Digital Library
Imaging at high spatial resolution: Soft x-ray microscopy to 15nm (open access)

Imaging at high spatial resolution: Soft x-ray microscopy to 15nm

Soft x-ray microscopy has now achieved 15 nm spatial resolution with new zone plates and bending magnet radiation. Combined with elemental sensitivity and flexible sample environment (applied magnetic or electric fields, wet samples, windows, overcoatings) this emerges as a valuable tool for nanoscience and nanotechnology, complimenting common electron and scanning tip microscopies. In this presentation we describe recent advances in spatial resolution, expectations for the near future, and applications to magnetic materials, bio-tomography, etc.
Date: April 5, 2006
Creator: Attwood, D.; Chao, W.; Anderson, E.; Liddle, J. A.; Harteneck, B.; Fischer, P. et al.
System: The UNT Digital Library
Optimization of Beam Injection into the First Accelerating Module at TTF With Cavity Dipole Mode Signals (open access)

Optimization of Beam Injection into the First Accelerating Module at TTF With Cavity Dipole Mode Signals

The TESLA Test Facility (TTF) is a user facility for intense VUV-FEL light. The facility is densely equipped with diagnostics, essential in obtaining the necessary beam parameters, in particular the low emittance. However there is no dedicated component for alignment of the beam in the accelerating modules, each containing eight superconducting cavities. Large beam offsets can lead to an increase of the beam emittance. The centering of the beam in these modules is therefore important, mostly at the low energy end. A misalignment of the first TTF module with respect to the gun axis has already been observed using cavity dipole modes. This paper presents the experimental results of the optimization of the beam injection into the first module, based on the monitoring of dipole modes through the couplers installed for wakefield damping. For this we use a spectrum analyzer together with a multiplexer. By scanning the beam position and tilt with two pairs of steerers, we can find the trajectory which minimizes the dipole modes amplitude. The impact of the beam steering in the module on the beam is discussed. A time domain setup is also being presented.
Date: April 10, 2006
Creator: Baboi, N.; Kreps, G.; Schlarb, H.; Wendt, M.; Frisch, J.; McCormick, D. et al.
System: The UNT Digital Library
Effects of covalency on the p-shell photoemission of transition metals: MnO (open access)

Effects of covalency on the p-shell photoemission of transition metals: MnO

This article discusses the effects of covalency on the p-shell photoemission of transition metals. The treatment of covalency has not been included previously in ab initio theoretical studies of the 2p-shell XPS of transition-metal complexes. In this work, covalent interactions between the metal and ligands are treated on an equal footing with spin-orbit splittings.
Date: April 13, 2006
Creator: Bagus, Paul S. & Ilton, Eugene S.
System: The UNT Digital Library
Actinide Targets for Neutron Cross Section Measurements (C) (open access)

Actinide Targets for Neutron Cross Section Measurements (C)

The Advanced Fuel Cycle Initiative (AFCI) and the Generation IV Reactor Initiative have demonstrated a lack of detailed neutron cross-sections for certain "minor" actinides, those other than the most common (235U, 238U, and 239Pu). For some closed-fuel-cycle reactor designs more than 50% of reactivity will, at some point, be derived from “minor” actinides that currently have poorly known (n,g) and (n,f) cross sections. A program of measurements under AFCI has begun to correct this. One of the initial hurdles has been to produce well-characterized, highly isotopically enriched, and chemically pure actinide targets on thin backings. Using a combination of resurrected techniques and new developments, we have made a series of targets including highly enriched 240Pu, and 242Pu. Thus far, we have electrodeposited these actinide targets. In the future, we plan to study reductive distillation to achieve homogeneous, adherent targets on thin metal foils and polymer backings. As we move forward, separated isotopes become scarcer, and safety concerns become greater. The chemical purification and electodeposition techniques will be described.
Date: April 1, 2006
Creator: Baker, J. D. & McGrath, C. A.
System: The UNT Digital Library
Biogeophysical effects of CO2-fertilization on global climate (open access)

Biogeophysical effects of CO2-fertilization on global climate

CO{sub 2}-fertilization affects plant growth, which modifies surface physical properties, altering the surface albedo, and fluxes of sensible and latent heat. We investigate how such CO{sub 2}-fertilization effects on vegetation and surface properties would affect the climate system. Using a global three-dimensional climate-carbon model that simulates vegetation dynamics, we compare two multi-century simulations: a ''Control'' simulation with no emissions, and a ''Physiol-noGHG'' simulation where physiological changes occur as a result of prescribed CO{sub 2} emissions, but where CO{sub 2}-induced greenhouse warming is not included. In our simulations, CO{sub 2}-fertilization produces warming; we obtain an annual- and global-mean warming of about 0.65 K (and land-only warming of 1.4 K) after 430 years. This century-scale warming is mostly due to a decreased surface albedo associated with the expansion of the Northern Hemisphere boreal forests. On decadal time scales, the CO{sub 2} uptake by afforestation should produce a cooling effect that exceeds this albedo-based warming; but if the forests remain in place, the CO{sub 2}-enhanced-greenhouse effect would diminish as the ocean equilibrates with the atmosphere, whereas the albedo effect would persist. Thus, on century time scales, there is the prospect for net warming from CO{sub 2}-fertilization of the land biosphere. Further study is …
Date: April 26, 2006
Creator: Bala, G.; Caldeira, K.; Mirin, A.; Wickett, M.; Delire, C. & Phillips, T. J.
System: The UNT Digital Library
Transverse coherent instability of a bunch in a rectangular potential well (open access)

Transverse coherent instability of a bunch in a rectangular potential well

Theory of transverse instability of a bunch in a rectangular potential well is developed. Series of equations adequately describing the instability is derived and solved both analytically and numerically. Dependence of the instability increment and threshold on bunch factor is investigated for various beam coupling impedances. The theory is applied to the Fermilab Recycler Ring.
Date: April 1, 2006
Creator: Balbekov, V.
System: The UNT Digital Library
Wakefields of Sub-Picosecond Electron Bunches (open access)

Wakefields of Sub-Picosecond Electron Bunches

We discuss wakefields excited by short bunches in accelerators. In particular, we review some of what has been learned in recent years concerning diffraction wakes, roughness impedance, coherent synchrotron radiation wakes, and the resistive wall wake, focusing on analytical solutions where possible. As examples, we apply formulas for these wakes to various parts of the Linac Coherent Light Source (LCLS) project. The longitudinal accelerator structure wake of the SLAC linac is an important ingredient in the LCLS bunch compression process. Of the wakes in the undulator region, the dominant one is the resistive wall wake of the beam pipe.
Date: April 19, 2006
Creator: Bane, Karl L. F.
System: The UNT Digital Library
Killing Two Birds with One Stone: Can Real-Time Pricing SupportRetail Competition and Demand Response? (open access)

Killing Two Birds with One Stone: Can Real-Time Pricing SupportRetail Competition and Demand Response?

As retail choice states reach the end of their transitional, rate-cap periods, state regulators must decide what type of default supply service to provide to customers that have not switched to a competitive retail supplier. In a growing number of states, regulators have adopted real-time pricing (RTP) as the default service for large commercial and industrial (C&I) customers. Although this trend is driven chiefly by policy objectives related to retail competition, default service RTP may have the added benefit of stimulating demand response. To evaluate the potential role of RTP as a means to both ends--retail market development and demand response--we conducted a comprehensive review of experience with default RTP in the U.S. and examined the emergence of RTP as a product offering by competitive retail suppliers. Across the ten utilities with default RTP in place in 2005, between 5% and 35% of the applicable load remained on the rate. Based on interviews with competitive retailers, we find evidence to suggest that a comparable amount of load in these states has switched to hourly pricing arrangements with competitive retailers. Many customers on default or competitive hourly pricing are paying prices indexed to the real-time spot market, and thus have no …
Date: April 25, 2006
Creator: Barbose, Galen; Bharvirkar, Ranjit; Goldman, Charles; Hopper,Nicole & Neenan, Bernie
System: The UNT Digital Library
Encouraging PV Adoption in New Market-Rate ResidentialConstruction: A Critical Review of Program Experiences to Date (open access)

Encouraging PV Adoption in New Market-Rate ResidentialConstruction: A Critical Review of Program Experiences to Date

In this paper, we review experiences with programs to support the deployment of photovoltaics (PV) in new, market-rate homes, drawing upon interviews with program managers around the country, project data, and publicly-available documentation on program design, impacts, and experiences. We focus on state clean energy funds, which have been established in 14 U.S. states to build markets for clean energy resources, as well as a select number of other state or local organizations whose activities are particularly noteworthy. We describe the types of programs implemented and their impacts to date, and discuss key issues and lessons learned for initiatives aimed at growing the new home market for PV.
Date: April 24, 2006
Creator: Barbose, Galen; Wiser, Ryan & Bolinger, Mark
System: The UNT Digital Library