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Measurement of the $WZ$ Cross Section and Triple Gauge Couplings in $p \bar p$ Collisions at $\sqrt{s} = 1.96$ TeV (open access)

Measurement of the $WZ$ Cross Section and Triple Gauge Couplings in $p \bar p$ Collisions at $\sqrt{s} = 1.96$ TeV

This Letter describes the current most precise measurement of the WZ production cross section as well as limits on anomalous WWZ couplings at a center-of-mass energy of 1.96 TeV in proton-antiproton collisions. The WZ candidates are reconstructed from decays containing three charged leptons and missing energy from a neutrino, where the charged leptons are either electrons or muons. Using data collected by the CDF II detector (7.1 fb{sup -1} of integrated luminosity), 64 candidate events are observed with the expected background contributing 8 {+-} 1 events. The measured total cross section {sigma}(p{bar p} {yields} WZ) = 3.93{sub -0.53}{sup +0.60}(stat){sub -0.46}{sup +0.59}(syst) pb is in good agreement with the standard model prediction of 3.50 {+-} 0.21. The same sample is used to set limits on anomalous WWZ couplings.
Date: February 1, 2012
Creator: Aaltonen, T.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A. et al.
System: The UNT Digital Library
Combined upper limit on Standard Model Higgs boson production at CDF (open access)

Combined upper limit on Standard Model Higgs boson production at CDF

The Higgs boson is the only elementary particle predicted by the Standard Model (SM) that has neither been confirmed nor refuted. The CDF collaboration has performed SM Higgs searches in many channels using p{bar p} collisions at a centre-of-mass energy {radical}s = 1.96 TeV. We present the latest combined Higgs boson search at CDF. Since the previous year's combination, the sensitivity is increased through the addition of new channels, the improvement of existing channels and the addition of new data samples. We also use the latest parton distribution functions and gg {yields} H theoretical cross sections when modelling the signal event yields. Using integrated luminosities of up to 8.2 fb{sup -1}, we observe a good agreement between data and the background prediction. Since we do not see a Higgs boson excess, we set 95% CL upper limits on the Higgs boson cross section in the range between 100 and 200 GeV/c{sup 2}, with 5 GeV/c{sup 2} increments. The observed (expected) limits for a 115 and a 165 GeV/c{sup 2} Higgs boson are 1.55 (1.49) and 0.75 (0.79) x SM, respectively. Since last year, the Higgs boson excluded range by CDF is extended to 156.5 - 173.7 and 100 - 104.5 …
Date: February 1, 2012
Creator: Adrian, Buzatu
System: The UNT Digital Library
Safeguards-By-Design: Guidance and Tools for Stakeholders (open access)

Safeguards-By-Design: Guidance and Tools for Stakeholders

Effective implementation of the Safeguards-by-Design (SBD) approach can help meet the challenges of global nuclear energy growth, by designing facilities that have improved safeguardability and reduced safeguards-related life cycle costs. The ultimate goal of SBD is to implement effective and efficient safeguards that reduce the burden to both the facility operator and the International Atomic Energy Agency. Since 2008, the National Nuclear Security Administration's Next Generation Safeguards Initiative's Safeguards By Design Project has initiated multiple studies and workshops with industry and regulatory stakeholders, including the IAEA, to develop relevant documents to support the implementation of SBD. These 'Good Practices Guides' describe facility and process design features that will facilitate implementation of effective nuclear material safeguards starting in the earliest phases of design through to final design. These guides, which are in their final editorial stages, start at a high level and then narrow down to specific nuclear fuel cycle facilities such as Light Water Reactors, Generation III/IV Reactors, High Temperature Gas Cooled Reactors, and Gas Centrifuge Enrichment Plants. Most recently, NGSI has begun development of a facility safeguardability assessment toolkit to assist the designer. This paper will review the current status of these efforts, provide some examples of these documents, …
Date: February 1, 2012
Creator: Schanfein, Mark & Johnson, Shirley
System: The UNT Digital Library
Intense Super-radiant X-rays from a Compact Source using a Nanocathode Array and Emittance Exchange (open access)

Intense Super-radiant X-rays from a Compact Source using a Nanocathode Array and Emittance Exchange

A novel method of producing intense short wavelength radiation from relativistic electrons is described. The electrons are periodically bunched at the wavelength of interest enabling in-phase super-radiant emission that is far more intense than from unbunched electrons. The periodic bunching is achieved in steps beginning with an array of beamlets emitted from a nanoengineered field emission array. The beamlets are then manipulated and converted to a longitudinal density modulation via a transverse to longitudinal emittance exchange. Periodic bunching at short wavelength is shown to be possible, and the partially coherent x-ray properties produced by Inverse Compton scattering from an intense laser are estimated. The proposed method increases the efficiency of x-ray production by several orders of magnitude, potentially enabling compact x-ray sources to produce brilliance and flux similar to major synchrotron facilities.
Date: February 1, 2012
Creator: Graves, W. S.; Kaertner, F. X.; Moncton, D. E. & Piot, P.
System: The UNT Digital Library
Impact of Transmission on Resource Adequacy in Systems with Wind and Solar Power: Preprint (open access)

Impact of Transmission on Resource Adequacy in Systems with Wind and Solar Power: Preprint

Variable generation is on track to become a significant contributor to electric power systems worldwide. Thus, it is important to analyze the effect that renewables will have on the reliability of systems. In this paper we present a new tool being implemented at the National Renewable Energy Laboratory, which allows the inclusion of variable generation in the power system resource adequacy. The tool is used to quantify the potential contribution of transmission to reliability in highly interconnected systems and an example is provided using the Western Interconnection footprint.
Date: February 1, 2012
Creator: Ibanez, E. & Milligan, M.
System: The UNT Digital Library
Ensemble Properties of Comets in the Sloan Digital Sky Survey (open access)

Ensemble Properties of Comets in the Sloan Digital Sky Survey

We present the ensemble properties of 31 comets (27 resolved and 4 unresolved) observed by the Sloan Digital Sky Survey (SDSS). This sample of comets represents about 1 comet per 10 million SDSS photometric objects. Five-band (u, g, r, i, z) photometry is used to determine the comets colors, sizes, surface brightness profiles, and rates of dust production in terms of the Afp formalism. We find that the cumulative luminosity function for the Jupiter Family Comets in our sample is well fit by a power law of the form N(<H) {proportional_to} 10{sup (0.49{+-}0.05)H} for H < 18, with evidence of a much shallower fit N(<H) {proportional_to} 10{sup (0.19{+-}0.03)H} for the faint (14.5 < H < 18) comets. The resolved comets show an extremely narrow distribution of colors (0.57 {+-} 0.05 in g - r for example), which are statistically indistinguishable from that of the Jupiter Trojans. Further, there is no evidence of correlation between color and physical, dynamical, or observational parameters for the observed comets.
Date: February 1, 2012
Creator: Solontoi, Michael; Ivezic, Zeljko; Juric, Mario; Becker, Andrew C.; Jones, Lynne; West, Andrew A. et al.
System: The UNT Digital Library
$B_s\to D_s/B\to D$ Semileptonic Form-Factor Ratios and Their Application to BR($B^0_s\to \mu^+\mu^-$) (open access)

$B_s\to D_s/B\to D$ Semileptonic Form-Factor Ratios and Their Application to BR($B^0_s\to \mu^+\mu^-$)

We calculate form-factor ratios between the semileptonic decays {bar B}{sup 0} {yields} D{sup +} {ell}{sup -}{bar {nu}} and {bar B}{sub s}{sup 0} {yields} D{sub s}{sup +}{ell}{sup -}{bar {nu}} with lattice QCD. These ratios are a key theoretical input in a new strategy to determine the fragmentation fractions of the neutral B decays, which are needed for measurements of BR(B{sub s}{sup 0} {yields} {mu}{sup +}{mu}{sup -}). They use the MILC ensembles of gauge configurations with 2 + 1 flavors of sea quarks at two lattice spacings of approximately 0.12 fm and 0.09 fm. We use the model-independent z parametrization to extrapolate their simulation results at small recoil toward maximum recoil. The results for the form-factor ratios are {line_integral}{sub 0}{sup (s)} (M{sub {pi}}{sup 2})/{line_integral}{sub 0}{sup (d)} (M{sub K}{sup 2}) = 1.046(44){sub stat.}(15){sub syst.} and {line_integral}{sub 0}{sup (s)} (M{sub {pi}}{sup 2})/{line_integral}{sub 0}{sup (d)} (M{sub {pi}}{sup 2}) = 1.054(47){sub stat.}(17){sub syst.}. In contrast to a QCD sum-rule calculation, no significant departure from U-spin (d {leftrightarrow} s) symmetry is observed.
Date: February 1, 2012
Creator: Bailey, Jon A.; Bazavov, A.; Bernard, C.; Bouchard, C. M.; DeTar, C.; Du, Daping et al.
System: The UNT Digital Library
SUSY searches at the Tevatron (open access)

SUSY searches at the Tevatron

The Tevatron collider has provided the CDF and D0 collaborations with large datasets as input to a rich program of physics beyond the standard model. The results presented here are from recent searches for SUSY particles using up to 6 fb{sup -1} of data. Supersymmetry (SUSY) [1] is one of the most favored theories beyond the standard model (SM). Each SM particle is associated to a sparticle whose spin differs by one half unit. This boson-fermion symmetry is obviously broken by some unknown mechanism. Even in the minimal supersymmetric extension of the SM (MSSM [2]) there are a large number of free parameters. To reduce this number one can introduce new assumptions on the symmetry breaking mechanism and build models based on minimal supergravity (as mSUGRA [3]) or on a Gauge Mediated Symmetry Breaking scenario (GMSB [4]), a top-down approach. Another possibility is to make phenomenological assumptions to reduce the number of particles accessible to the experiment while keeping some of the properties of the above models (bottom-up approach). As the sparticles are heavy, to produce them one has to make collisions at the highest center of mass energy. The Tevatron was the best place for discovery until the start …
Date: February 1, 2012
Creator: Jaffre, Michel
System: The UNT Digital Library
Imaging Techniques for Relativistic Beams: Issues and Limitations (open access)

Imaging Techniques for Relativistic Beams: Issues and Limitations

Characterizations of transverse profiles for low-power beams in the accelerators of the proposed linear colliders (ILC and CLIC) using imaging techniques are being evaluated. Assessments of the issues and limitations for imaging relativistic beams with intercepting scintillator or optical transition radiation screens are presented based on low-energy tests at the Fermilab A0 photoinjector and are planned for the Advanced Superconducting Test Accelerator at Fermilab. We have described several of the issues and limitations one encounters with the imaging of relativistic electron beams. We have reported our initial tests at the A0PI facility and our plans to extend these studies to the GeV scale at the ASTA facility. We also have plans to test these concepts with 23-GeV beams at the FACET facility at SLAC in the coming year. It appears the future remains bright for imaging techniques in ILC-relevant parameter space.
Date: February 1, 2012
Creator: Lumpkin, Alex H. & Wendt, Manfred
System: The UNT Digital Library
Modeling of coupled thermodynamic and geomechanical performance of underground compressed air energy storage (CAES) in lined rock caverns (open access)

Modeling of coupled thermodynamic and geomechanical performance of underground compressed air energy storage (CAES) in lined rock caverns

We applied coupled nonisothermal, multiphase fluid flow and geomechanical numerical modeling to study the coupled thermodynamic and geomechanical performance of underground compressed air energy storage (CAES) in concrete-lined rock caverns. The paper focuses on CAES in lined caverns at relatively shallow depth (e.g., 100 m depth) in which a typical CAES operational pressure of 5 to 8 MPa is significantly higher than both ambient fluid pressure and in situ stress. We simulated a storage operation that included cyclic compression and decompression of air in the cavern, and investigated how pressure, temperature and stress evolve over several months of operation. We analyzed two different lining options, both with a 50 cm thick low permeability concrete lining, but in one case with an internal synthetic seal such as steel or rubber. For our simulated CAES system, the thermodynamic analysis showed that 96.7% of the energy injected during compression could be recovered during subsequent decompression, while 3.3% of the energy was lost by heat conduction to the surrounding media. Our geomechanical analysis showed that tensile effective stresses as high as 8 MPa could develop in the lining as a result of the air pressure exerted on the inner surface of the lining, whereas …
Date: February 1, 2012
Creator: Rutqvist, J.; Kim, H. -M.; Ryu, D. -W.; Synn, J. -H. & Song, W. -K.
System: The UNT Digital Library
Long-Term Running Experience with the Silicon Micro-Strip Tracker at the D{\O} Detector (open access)

Long-Term Running Experience with the Silicon Micro-Strip Tracker at the D{\O} Detector

The Silicon Micro-strip Tracker (SMT) at the D0 experiment in the Fermilab Tevatron collider has been operating since 2001. In 2006, an additional layer, referred to as 'Layer 0', was installed to improve impact parameter resolution and compensate for detector degradation due to radiation damage to the original innermost SMT layer. The SMT detector provides valuable tracking and vertexing information for the experiment. This contribution will highlight aspects of the long term operation of the SMT, including the impact of the silicon readout test-stand. Due to the full integration of the test-stand into the D0 trigger framework, this test-stand provides an advantageous tool for training of new experts and studying subtle effects in the SMT while minimizing impact on the global data acquisition.
Date: February 1, 2012
Creator: Jung, Andreas W.; Cherry, M.; Edmunds, D.; Johnson, M.; Matulik, M.; Utes, M. et al.
System: The UNT Digital Library
Reflections on the nature of genius: on the 300th anniversay of Mikhail Lomonosov (1711-1765) (open access)

Reflections on the nature of genius: on the 300th anniversay of Mikhail Lomonosov (1711-1765)

This presentation goes beyond celebratory narration of the life and scientific achievements of Russia's first modern scientist Mikhail Vasilievich Lomonosov (1711-1765). Coming from the notion of complexity of sciences, we introduce 'a genius formula' G = TBD for semi-qualitative evaluation of a person's impact on the society, distinguish two type of geniuses, give several examples and draw general conclusions. The work largely follows presentation at the Fermilab Colloquium in November of 2011.
Date: February 1, 2012
Creator: Shiltsev, V.
System: The UNT Digital Library
An investigation of the effect of pore scale flow on average geochemical reaction rates using direct numerical simulation (open access)

An investigation of the effect of pore scale flow on average geochemical reaction rates using direct numerical simulation

The scale-dependence of geochemical reaction rates hinders their use in continuum scale models intended for the interpretation and prediction of chemical fate and transport in subsurface environments such as those considered for geologic sequestration of CO{sub 2}. Processes that take place at the pore scale, especially those involving mass transport limitations to reactive surfaces, may contribute to the discrepancy commonly observed between laboratory-determined and continuum-scale or field rates. Here, the dependence of mineral dissolution rates on the pore structure of the porous media is investigated by means of pore scale modeling of flow and multicomponent reactive transport. The pore scale model is comprised of high performance simulation tools and algorithms for incompressible flow and conservative transport combined with a general-purpose multicomponent geochemical reaction code. The model performs direct numerical simulation of reactive transport based on an operator-splitting approach to coupling transport and reactions. The approach is validated with a Poiseuille flow single-pore experiment and verified with an equivalent 1D continuum-scale model of a capillary tube packed with calcite spheres. Using the case of calcite dissolution as an example, the high resolution model is used to demonstrate that non-uniformity in the flow field at the pore scale has the effect of …
Date: February 1, 2012
Creator: Rafa, S. Molins; Trebotich, D.; Steefel, C. I. & Shen, C.
System: The UNT Digital Library
Residential Energy Efficiency Research Planning Meeting Summary Report: Washington, D.C. - October 27-28, 2011 (open access)

Residential Energy Efficiency Research Planning Meeting Summary Report: Washington, D.C. - October 27-28, 2011

This report summarizes key findings and outcomes from the U.S. Department of Energy's Building America Residential Energy Efficiency Research Planning meeting, held on October 28-29, 2011, in Washington, D.C.
Date: February 1, 2012
Creator: unknown
System: The UNT Digital Library
Charge independence, charge symmetry breaking in the S-wave nucleon-nucleon interaction, and renormalization (open access)

Charge independence, charge symmetry breaking in the S-wave nucleon-nucleon interaction, and renormalization

We study the interplay between charge symmetry breaking and renormalization in the NN system for S-waves. We find a set of universality relations which disentangle explicitly the known long distance dynamics from low energy parameters and extend them to the Coulomb case. We analyze within such an approach the One-Boson-Exchange potential and the theoretical conditions which allow to relate the proton-neutron, proton-proton and neutron-neutron scattering observables without the introduction of extra new parameters and providing good phenomenological success.
Date: February 1, 2012
Creator: Alvaro Calle Cordon,Manuel Pavon Valderrama,Enrique Ruiz Arriola
System: The UNT Digital Library
Heat Pump Water Heater Technology Assessment Based on Laboratory Research and Energy Simulation Models: Preprint (open access)

Heat Pump Water Heater Technology Assessment Based on Laboratory Research and Energy Simulation Models: Preprint

This paper explores the laboratory performance of five integrated Heat Pump Water Heaters (HPWHs) across a wide range of operating conditions representative of US climate regions. Laboratory results demonstrate the efficiency of this technology under most of the conditions tested and show that differences in control schemes and design features impact the performance of the individual units. These results were used to understand current model limitations, and then to bracket the energy savings potential for HPWH technology in various US climate regions. Simulation results show that HPWHs are expected to provide significant energy savings in many climate zones when compared to other types of water heaters (up to 64%, including impact on HVAC systems).
Date: February 1, 2012
Creator: Hudon, K.; Sparn, B.; Christensen, D. & Maguire, J.
System: The UNT Digital Library
Understanding Contamination; Twenty Years of Simulating Radiological Contamination (open access)

Understanding Contamination; Twenty Years of Simulating Radiological Contamination

A wide variety of simulated contamination methods have been developed by researchers to reproducibly test radiological decontamination methods. Some twenty years ago a method of non-radioactive contamination simulation was proposed at the Idaho National Laboratory (INL) that mimicked the character of radioactive cesium and zirconium contamination on stainless steel. It involved baking the contamination into the surface of the stainless steel in order to 'fix' it into a tenacious, tightly bound oxide layer. This type of contamination was particularly applicable to nuclear processing facilities (and nuclear reactors) where oxide growth and exchange of radioactive materials within the oxide layer became the predominant model for material/contaminant interaction. Additional simulation methods and their empirically derived basis (from a nuclear fuel reprocessing facility) are discussed. In the last ten years the INL, working with the Defense Advanced Research Projects Agency (DARPA) and the National Homeland Security Research Center (NHSRC), has continued to develop contamination simulation methodologies. The most notable of these newer methodologies was developed to compare the efficacy of different decontamination technologies against radiological dispersal device (RDD, 'dirty bomb') type of contamination. There are many different scenarios for how RDD contamination may be spread, but the most commonly used one at the …
Date: February 1, 2012
Creator: Snyder, Emily; Drake, John & James, Ryan
System: The UNT Digital Library
Differential isotopic fractionation during Cr(VI) reduction by an aquifer-derived bacterium under arobic versus denitrifying conditions (open access)

Differential isotopic fractionation during Cr(VI) reduction by an aquifer-derived bacterium under arobic versus denitrifying conditions

We studied Cr isotopic fractionation during Cr(VI) reduction by Pseudomonas stutzeri strain RCH2. Despite the fact that strain RCH2 reduces Cr(VI) co-metabolically under both aerobic and denitrifying conditions and at similar specific rates, fractionation was markedly different under these two conditions (ε ~2� aerobically and ~0.4� under denitrifying conditions).
Date: February 1, 2012
Creator: Han, R.; Qin, L.; Brown, S. T.; Christensen, J. N. & Beller, H. R.
System: The UNT Digital Library
Comparison of improved Aura Tropospheric Emission Spectrometer (TES) CO{sub 2} with HIPPO and SGP aircraft profile measurements (open access)

Comparison of improved Aura Tropospheric Emission Spectrometer (TES) CO{sub 2} with HIPPO and SGP aircraft profile measurements

Comparisons are made between mid-tropospheric Tropospheric Emission Spectrometer (TES) carbon dioxide (CO{sub 2}) satellite measurements and ocean profiles from three Hiaper Pole-to-Pole Observations (HIPPO) campaigns and land aircraft profiles from the United States Southern Great Plains (SGP) Atmospheric Radiation Measurement (ARM) site over a 4-yr period. These comparisons are used to characterize the bias in the TES CO{sub 2} estimates and to assess whether calculated and actual uncertainties and sensitivities are consistent. The HIPPO dataset is one of the few datasets spanning the altitude range where TES CO{sub 2} estimates are sensitive, which is especially important for characterization of biases. We find that TES CO{sub 2} estimates capture the seasonal and latitudinal gradients observed by HIPPO CO{sub 2} measurements; actual errors range from 0.8–1.2 ppm, depending on the campaign, and are approximately 1.4 times larger than the predicted errors. The bias of TES versus HIPPO is within 0.85 ppm for each of the 3 campaigns; however several of the sub-tropical TES CO{sub 2} estimates are lower than expected based on the calculated errors. Comparisons of aircraft flask profiles, which are measured from the surface to 5 km, to TES CO{sub 2} at the SGP ARM site show good agreement with …
Date: February 1, 2012
Creator: Kulawik, S. S.; Worden, J. R.; Wofsy, S. C.; Biraud, S. C.; Nassar, R.; Jones, D. B.A. et al.
System: The UNT Digital Library
Search for Anomalous Production of Multiple Leptons in Association With $W$ and $Z$ Bosons at Cdf (open access)

Search for Anomalous Production of Multiple Leptons in Association With $W$ and $Z$ Bosons at Cdf

This paper presents a search for anomalous production of multiple low-energy leptons in association with a W or Z boson using events collected at the CDF experiment corresponding to 5.1 fb{sup -1} of integrated luminosity. This search is sensitive to a wide range of topologies with low-momentum leptons, including those with the leptons near one another. The observed rates of production of additional electrons and muons are compared with the standard model predictions. No indications of phenomena beyond the standard model are found. A 95% confidence level limit is presented on the production cross section for a benchmark model of supersymmetric hidden-valley Higgs production. Particle identification efficiencies are also provided to enable the calculation of limits on additional models.
Date: February 1, 2012
Creator: Aaltonen, T.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A. et al.
System: The UNT Digital Library
Particle Physics in a Season of Change (open access)

Particle Physics in a Season of Change

A digest of the authors opening remarks at the 2011 Hadron Collider Physics Symposium. I have chosen my title to reflect the transitions we are living through, in particle physics overall and in hadron collider physics in particular. Data-taking has ended at the Tevatron, with {approx} 12 fb{sup -1} of {bar p}p interactions delivered to CDF and D0 at {radical}s = 1.96 TeV. The Large Hadron Collider has registered a spectacular first full-year run, with ATLAS and CMS seeing > 5 fb{sup -1}, LHCb recording {approx} 1 fb{sup -1}, and ALICE logging nearly 5 pb{sup -1} of pp data at {radical}s = 7 TeV, plus a healthy dose of Pb-Pb collisions. The transition to a new energy regime and new realms of instantaneous luminosity exceeding 3.5 x 10{sup 33} cm{sup -2} s{sup -1} has brought the advantage of enhanced physics reach and the challenge of pile-up reaching {approx} 15 interactions per beam crossing. I am happy to record that what the experiments have (not) found so far has roused some of my theoretical colleagues from years of complacency and stimulated them to think anew about what the TeV scale might hold. We theorists have had plenty of time to explore …
Date: February 1, 2012
Creator: Quigg, Chris
System: The UNT Digital Library
Combination of CDF and D0 measurements of the $W$ boson helicity in top quark decays (open access)

Combination of CDF and D0 measurements of the $W$ boson helicity in top quark decays

We report the combination of recent measurements of the helicity of the W boson from top quark decay by the CDF and D0 collaborations, based on data samples corresponding to integrated luminosities of 2.7-5.4 fb{sup -1} of p{bar p} collisions collected during Run II of the Fermilab Tevatron Collider. Combining measurements that simultaneously determine the fractions of W bosons with longitudinal (f{sub 0}) and right-handed (f{sub +}) helicities, we find f{sub 0} = 0.722 {+-} 0.081 [{+-} 0.062 (stat.) {+-} 0.052 (syst.)] and f{sub +} = -0.033 {+-} 0.046 [{+-} 0.034 (stat.) {+-} 0.031 (syst.)]. Combining measurements where one of the helicity fractions is fixed to the value expected in the standard model, we find f{sub 0} = 0.682 {+-} 0.057 [{+-} 0.035 (stat.) {+-} 0.046 (syst.)] and f{sub +} = ?0.015 {+-} 0.035 [{+-} 0.018 (stat.) {+-} 0.030 (syst.)]. The results are consistent with standard model expectations.
Date: February 1, 2012
Creator: Aaltonen, T.; Abazov, V. M.; Abbott, B.; Acharya, B. S.; Adams, M.; Adams, T. et al.
System: The UNT Digital Library
Search for a dark matter candidate produced in association with a single top quark in $p\bar{p}$ collisions at $\sqrt{s} = 1.96$ TeV (open access)

Search for a dark matter candidate produced in association with a single top quark in $p\bar{p}$ collisions at $\sqrt{s} = 1.96$ TeV

We report a new search for dark matter in a data sample of an integrated luminosity of 7.7 fb{sup -1} of Tevatron p{bar p} collisions at {radical}s = 1.96 TeV, collected by the CDF II detector. We search for production of a dark matter candidate, D, in association with a single top quark. We consider the hadronic decay mode of the top quark exclusively, yielding a final state of three jets with missing transverse energy. The data are consistent with the standard model; we thus set 95% confidence level upper limits on the cross section of the process p{bar p} {yields} t + D as a function of the mass of the dark-matter candidate. The limits are approximately 0.5 pb for a dark-matter particle with mass in the range of 0 - 150 GeV/c{sup 2}.
Date: February 1, 2012
Creator: Aaltonen, T.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A. et al.
System: The UNT Digital Library
2011 Alkaline Membrane Fuel Cell Workshop Final Report (open access)

2011 Alkaline Membrane Fuel Cell Workshop Final Report

A workshop addressing the current state-of-the-art in alkaline membrane fuel cells (AMFCs) was held May 8-9, 2011, at the Crystal Gateway Marriott in Arlington, Virginia. This workshop was the second of its kind, with the first being held December 11-13, 2006, in Phoenix, Arizona. The 2011 workshop and associated workshop report were created to assess the current state of AMFC technology (taking into account recent advances), investigate the performance potential of AMFC systems across all possible power ranges and applications, and identify the key research needs for commercial competitiveness in a variety of areas.
Date: February 1, 2012
Creator: Pivovar, B.
System: The UNT Digital Library