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99
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Nuclear physics with a medium-energy Electron-Ion Collider
A polarized ep/eA collider (Electron-Ion Collider, or EIC) with variable center-of-mass energy {radical}s {approx} 20-70 GeV and a luminosity {approx}10{sup 34} cm{sup -2} s{sup -1} would be uniquely suited to address several outstanding questions of Quantum Chromodynamics (QCD) and the microscopic structure of hadrons and nuclei: (i) the three-dimensional structure of the nucleon in QCD (sea quark and gluon spatial distributions, orbital motion, polarization, correlations); (ii) the fundamental color fields in nuclei (nuclear parton densities, shadowing, coherence effects, color transparency); (iii) the conversion of color charge to hadrons (fragmentation, parton propagation through matter, in-medium jets). We briefly review the conceptual aspects of these questions and the measurements that would address them, emphasizing the qualitatively new information that could be obtained with the collider. Such a medium-energy EIC could be realized at Jefferson Lab after the 12 GeV Upgrade (MEIC), or at Brookhaven National Lab as the low-energy stage of eRHIC.
Date:
June 1, 2012
Creator:
A. Accardi, V. Guzey, A. Prokudin, C. Weiss
Object Type:
Article
System:
The UNT Digital Library
Extending Performance and Evaluating Risks of PV Systems Failure Using a Fault Tree and Event Tree Approach: Analysis of the Possible Application
Performance and reliability of photovoltaic (PV) systems are important issues in the overall evaluation of a PV plant and its components. While performance is connected to the amount of energy produced by the PV installation in the working environmental conditions, reliability impacts the availability of the system to produce the expected amount of energy. In both cases, the evaluation should be done considering information and data coming from indoor as well as outdoor tests. In this paper a way of re-thinking performance, giving it a probabilistic connotation, and connecting the two concepts of performance and reliability is proposed. The paper follows a theoretical approach and discusses the way to obtaining such information, facing benefits and problems. The proposed probabilistic performance accounts for the probability of the system to function correctly, thus passing through the complementary evaluation of the probability of system malfunctions and consequences. Scenarios have to be identified where the system is not functioning properly or at all. They are expected to be combined in a probabilistic safety analysis (PSA) based approach, providing not only the required probability, but also being capable of giving a prioritization of the risks and the most dominant scenario associated to a specific situation. …
Date:
June 3, 2012
Creator:
A., Colli
Object Type:
Article
System:
The UNT Digital Library
Search for High-Mass States with One Lepton Plus Missing Transverse Momentum in Proton-Proton Collisions at $\sqrt{s} with the ATLAS Detector
The ATLAS detector is used to search for high-mass states, such as heavy charged gauge bosons (W{prime},W*), decaying to a charged lepton (electron or muon) and a neutrino. Results are presented based on the analysis of ppcollisions at a center-of-mass energy of 7 TeV corresponding to an integrated luminosity of 36 pb{sup -1}. No excess beyond standard model expectations is observed. A W{prime} with sequential standard model couplings is excluded at 95% confidence level for masses below 1.49 TeV, and a W* (charged chiral boson) for masses below 1.35 TeV.
Date:
June 20, 2012
Creator:
Aad, Georges; Abbott, Brad; Abdallah, Jalal; Abdelalim, Ahmed Ali; Abdesselam, Abdelouahab; Abdinov, Ovsat et al.
Object Type:
Article
System:
The UNT Digital Library
Diffractive Dijet Production in $\bar{p}p$ Collisions at $\sqrt{s}=1.96$ TeV
We report on a study of diffractive dijet production in {bar p}p collisions at {radical}s = 1.96 TeV using the CDF II detector at the Fermilab Tevatron {bar p}p collider. A data sample from 310 pb{sup -1} of integrated luminosity collected by triggering on a high transverse energy jet, E{sub T}{sup jet}, in coincidence with a recoil antiproton detected in a Roman pot spectrometer is used to measure the ratio of single-diffractive to inclusive-dijet event rates as a function of x{sup {bar p}} of the interacting parton in the antiproton, the Bjorken-x, x{sub Bj}{sup {bar p}}, and a Q{sup 2} {approx} (E{sub T}{sup jet}){sup 2} in the ranges 10{sup -3} < x{sub Bj}{sup {bar p}} < 10{sup -1} and 10{sup 2} < Q{sup 2} < 10{sup 4} GeV{sup 2}, respectively. Results are presented for the region of {bar p}-momentum-loss fraction 0.03 < {zeta}{sub {bar p}} < 0.09 and a four-momentum transfer squared t{sub {bar p}} > -4 GeV{sup 2}. The t{sub {bar p}} dependence is measured as a function of Q{sup 2} and x{sub Bj}{sup {bar p}} and compared with that of inclusive single diffraction dissociation. We find weak x{sub Bj}{sup bar p}} and Q{sup 2} dependencies in the ratio …
Date:
June 1, 2012
Creator:
Aaltonen, T.; Albrow, M.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A. et al.
Object Type:
Article
System:
The UNT Digital Library
Measurement of the differential cross section $d\sigma/dt$ in elastic $p\bar{p}$ scattering at $\sqrt{s}=1.96$ TeV
We present a measurement of the elastic differential cross section differential cross section d{sigma}(p{bar p}{yields}p{bar p})/dt as a function of the four-momentum-transfer squared t. The data sample corresponds to an integrated luminosity of {approx}31 nb{sup -1} collected with the D0 detector using dedicated Tevatron p{bar p} Collider operating conditions at {radical}s = 1.96 TeV and covers the range 0.26 < |t| < 1.2 GeV{sup 2}. For |t| < 0.6 GeV{sup 2}, d{sigma}/dt is described by an exponential function of the form Ae{sup -b|t|} with a slope parameter b = 16.86 {+-} 0.10 (stat) {+-} 0.20 (syst) GeV{sup -2}. A change in slope is observed at |t| {approx} 0.6 GeV{sup 2}, followed by a more gradual |t| dependence with increasing values of |t|.
Date:
June 1, 2012
Creator:
Abazov, V. M.; Abbott, B.; Acharya, B. S.; Adams, M.; Adams, T.; Alexeev, G. D. et al.
Object Type:
Article
System:
The UNT Digital Library
AGR-2 Data Qualification Report for ATR Cycles 149B, 150A, 150B, 151A, and 151B
This report provides the data qualification status of AGR-2 fuel irradiation experimental data from Advanced Test Reactor (ATR) cycles 149B, 150A, 150B, 151A, and 151B), as recorded in the Nuclear Data Management and Analysis System (NDMAS). The AGR-2 data streams addressed include thermocouple temperatures, sweep gas data (flow rate, pressure, and moisture content), and fission product monitoring system (FPMS) data for each of the six capsules in the experiment. A total of 3,307,500 5-minute thermocouple and sweep gas data records were received and processed by NDMAS for this period. There are no AGR-2 data for cycle 150A because the experiment was removed from the reactor. Of these data, 82.2% were determined to be Qualified based on NDMAS accuracy testing and data validity assessment. There were 450,557 Failed temperature records due to thermocouple failures, and 138,528 Failed gas flow records due to gas flow cross-talk and leakage problems that occurred in the capsules after cycle 150A. For FPMS data, NDMAS received and processed preliminary release rate and release-to-birth rate ratio (R/B) data for the first three reactor cycles (cycles 149B, 150B, and 151B). This data consists of 45,983 release rate records and 45,235 R/B records for the 12 radionuclides reported. The …
Date:
June 1, 2012
Creator:
Abbott, Michael L. & Pham, Binh T.
Object Type:
Report
System:
The UNT Digital Library
Boosted Objects: A Probe of Beyond the Standard Model Physics
We present the report of the hadronic working group of the BOOST2010 workshop held at the University of Oxford in June 2010. The first part contains a review of the potential of hadronic decays of highly boosted particles as an aid for discovery at the LHC and a discussion of the status of tools developed to meet the challenge of reconstructing and isolating these topologies. In the second part, we present new results comparing the performance of jet grooming techniques and top tagging algorithms on a common set of benchmark channels. We also study the sensitivity of jet substructure observables to the uncertainties in Monte Carlo predictions.
Date:
June 12, 2012
Creator:
Abdesselam, A.; U., /Oxford; Kuutmann, E.Bergeaas; /DESY; Bitenc, U.; U., /Freiburg et al.
Object Type:
Article
System:
The UNT Digital Library
Insights Into the High-Energy Gamma-Ray Emission of Markarian 501 From Extensive Multifrequency Observations in the Fermi Era
None
Date:
June 14, 2012
Creator:
Abdo, A. A.; Ackermann, M.; Ajello, M.; Allafort, A.; Baldini, L.; Ballet, J. et al.
Object Type:
Article
System:
The UNT Digital Library
Flooding Events: CRS Experts
This table provides access to names and contact information for Congressional Research Service (CRS) experts on policy concerns relating to flooding events in the United States. Policy areas identified include impacts, response and recovery, mitigation, and federal financing.
Date:
June 27, 2012
Creator:
Abel, Amy
Object Type:
Report
System:
The UNT Digital Library
PRECEDENTS FOR AUTHORIZATION OF CONTENTS USING DOSE RATE MEASUREMENTS
For the transportation of Radioactive Material (RAM) packages, the requirements for the maximum allowed dose rate at the package surface and in its vicinity are given in Title 10 of the Code of Federal Regulations, Section 71.47. The regulations are based on the acceptable dose rates to which the public, workers, and the environment may be exposed. As such, the regulations specify dose rates, rather than quantity of radioactive isotopes and require monitoring to confirm the requirements are met. 10CFR71.47 requires that each package of radioactive materials offered for transportation must be designed and prepared for shipment so that under conditions normally incident to transportation the radiation level does not exceed 2 mSv/h (200 mrem/h) at any point on the external Surface of the package, and the transport index does not exceed 10. Before shipment, the dose rate of the package is determined by measurement, ensuring that it conforms to the regulatory limits, regardless of any analyses. This is the requirement for all certified packagings. This paper discusses the requirements for establishing the dose rates when shipping RAM packages and the precedents for meeting these requirements by measurement.
Date:
June 5, 2012
Creator:
Abramczyk, G.; Bellamy, S.; Nathan, S. & Loftin, B.
Object Type:
Article
System:
The UNT Digital Library
Cornell Fuel Cell Institute: Materials Discovery to Enable Fuel Cell Technologies
The discovery and understanding of new, improved materials to advance fuel cell technology are the objectives of the Cornell Fuel Cell Institute (CFCI) research program. CFCI was initially formed in 2003. This report highlights the accomplishments from 2006-2009. Many of the grand challenges in energy science and technology are based on the need for materials with greatly improved or even revolutionary properties and performance. This is certainly true for fuel cells, which have the promise of being highly efficient in the conversion of chemical energy to electrical energy. Fuel cells offer the possibility of efficiencies perhaps up to 90 % based on the free energy of reaction. Here, the challenges are clearly in the materials used to construct the heart of the fuel cell: the membrane electrode assembly (MEA). The MEA consists of two electrodes separated by an ionically conducting membrane. Each electrode is a nanocomposite of electronically conducting catalyst support, ionic conductor and open porosity, that together form three percolation networks that must connect to each catalyst nanoparticle; otherwise the catalyst is inactive. This report highlights the findings of the three years completing the CFCI funding, and incudes developments in materials for electrocatalyts, catalyst supports, materials with structured and …
Date:
June 29, 2012
Creator:
Abruna, H. D. & DiSalvo, Francis J.
Object Type:
Report
System:
The UNT Digital Library
Detection of a Spectral Break in the Extra Hard Component of GRB 090926A
None
Date:
June 12, 2012
Creator:
Ackermann, M.; Ajello, M.; Asano, K.; Axelsson, M.; Baldini, L.; Ballet, J. et al.
Object Type:
Article
System:
The UNT Digital Library
Fermi-LAT Search for Pulsar Wind Nebulae Around Gamma-Ray Pulsars
None
Date:
June 15, 2012
Creator:
Ackermann, M.; Ajello, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D. et al.
Object Type:
Article
System:
The UNT Digital Library
A Terrestrial Search for Dark Contents of the Vacuum, Such as Dark Energy, Using Atom Interferometry
We describe the theory and first experimental work on our concept for searching on earth for the presence of dark contents of the vacuum (DCV) using atom interferometry. Specifically, we have in mind any DCV that has not yet been detected on a laboratory scale, but which might manifest itself as dark energy on the cosmological scale. The experimental method uses two atom interferometers to cancel the effect of earth's gravity and diverse noise sources. It depends upon two assumptions: first, that the DCV possesses some space inhomogeneity in density, and second that it exerts a sufficiently strong nongravitational force on matter. The motion of the apparatus through the DCV should then lead to an irregular variation in the detected matter-wave phase shift. We discuss the nature of this signal and note the problem of distinguishing it from instrumental noise. We also discuss the relation of our experiment to what might be learned by studying the noise in gravitational wave detectors such as LIGO. The paper concludes with a projection that a future search of this nature might be carried out using an atom interferometer in an orbiting satellite. The laboratory apparatus is now being constructed.
Date:
June 11, 2012
Creator:
Adler, Ronald J.; /Stanford U., HEPL /San Francisco State U.; Muller, Holger; /UC, Berkeley; Perl, Martin L. & /KIPAC, Menlo Park /SLAC
Object Type:
Article
System:
The UNT Digital Library
Majorana Demonstrator Bolted Joint Mechanical and Thermal Analysis
The MAJORANA DEMONSTRATOR is designed to probe for neutrinoless double-beta decay, an extremely rare process with a half-life in the order of 1026 years. The experiment uses an ultra-low background, high-purity germanium detector array. The germanium crystals are both the source and the detector in this experiment. Operating these crystals as ionizing radiation detectors requires having them under cryogenic conditions (below 90 K). A liquid nitrogen thermosyphon is used to extract the heat from the detectors. The detector channels are arranged in strings and thermally coupled to the thermosyphon through a cold plate. The cold plate is joined to the thermosyphon by a bolted joint. This circular plate is housed inside the cryostat can. This document provides a detailed study of the bolted joint that connects the cold plate and the thermosyphon. An analysis of the mechanical and thermal properties of this bolted joint is presented. The force applied to the joint is derived from the torque applied to each one of the six bolts that form the joint. The thermal conductivity of the joint is measured as a function of applied force. The required heat conductivity for a successful experiment is the combination of the thermal conductivity of the …
Date:
June 1, 2012
Creator:
Aguayo Navarrete, Estanislao; Reid, Douglas J. & Fast, James E.
Object Type:
Report
System:
The UNT Digital Library
Combined Limits on WIMPs from the CDMS and EDELWEISS Experiments
this is a report on WIMPs and CDMS and EDELWEISS Experiments
Date:
June 1, 2012
Creator:
Ahmed, Z.; Akerib, D. S.; Armengaud, E.; Arrenberg, S.; Augier, C.; Bailey, C. N. et al.
Object Type:
Article
System:
The UNT Digital Library
Results from a Low-Energy Analysis of the CDMS II Germanium Data
None
Date:
June 4, 2012
Creator:
Ahmed, Z.; Akerib, D. S.; Arrenberg, S.; Bailey, C. N.; Balakishiyeva, D.; Baudis, L. et al.
Object Type:
Article
System:
The UNT Digital Library
Search for Inelastic Dark Matter with the CDMS II Experiment
None
Date:
June 4, 2012
Creator:
Ahmed, Z.; Akerib, D. S.; Arrenberg, S.; Bailey, C. N.; Balakishiyeva, D.; Baudis, L. et al.
Object Type:
Article
System:
The UNT Digital Library
Process Optimization for High Efficiency Heterojunction c-Si Solar Cells Fabrication Using Hot-Wire Chemical Vapor Deposition: Preprint
The researchers extensively studied the effects of annealing or thermal history of cell process on the minority carrier lifetimes of FZ n-type c-Si wafers with various i-layer thicknesses from 5 to 60 nm, substrate temperatures from 100 to 350 degrees C, doped layers both p- and n-types, and transparent conducting oxide (TCO).
Date:
June 1, 2012
Creator:
Ai, Y.; Yuan, H. C.; Page, M.; Nemeth, W.; Roybal, L. & Wang, Q.
Object Type:
Article
System:
The UNT Digital Library
A Low-threshold Analysis of CDMS Shallow-site Data
Data taken during the final shallow-site run of the first tower of the Cryogenic Dark Matter Search (CDMS II) detectors have been reanalyzed with improved sensitivity to small energy depositions. Four {approx}224 g germanium and two {approx}105 g silicon detectors were operated at the Stanford Underground Facility (SUF) between December 2001 and June 2002, yielding 118 live days of raw exposure. Three of the germanium and both silicon detectors were analyzed with a new low-threshold technique, making it possible to lower the germanium and silicon analysis thresholds down to the actual trigger thresholds of {approx}1 and {approx}2 keV, respectively. Limits on the spin-independent cross section for weakly interacting massive particles (WIMPs) to elastically scatter from nuclei based on these data exclude interesting parameter space for WIMPs with masses below 9 GeV/c{sup 2}. Under standard halo assumptions, these data partially exclude parameter space favored by interpretations of the DAMA/LIBRA and CoGeNT experiments data as WIMP signals, and exclude new parameter space for WIMP masses between 3 and 4 GeV/c{sup 2}.
Date:
June 4, 2012
Creator:
Akerib, D. S.; Attisha, M. J.; Baudis, L.; Bauer, D. A.; Bolozdynya, A. I.; Brink, P. L. et al.
Object Type:
Article
System:
The UNT Digital Library
SELECTION OF SURPLUS PLUTONIUM MATERIALS FOR DISPOSITION TO WIPP
The U.S. Department of Energy (DOE) is preparing a Surplus Plutonium Disposition (SPD) Supplemental Environmental Impact Statement (SEIS). Included in the evaluation are up to 6 metric tons (MT) of plutonium in the form of impure oxides and metals for which a disposition plan has not been decided, among options that include preparation as feed for the Mixed Oxide Fuel Fabrication Facility; disposing to high-level waste through the Savannah River Site (SRS) HB Line and H Canyon; can-in-canister disposal using the SRS Defense Waste Processing Facility; and preparation for disposal at the Waste Isolation Pilot Plant (WIPP). DOE and SRS have identified at least 0.5 MT of plutonium that, because of high levels of chemical and isotopic impurities, is impractical for disposition by methods other than the WIPP pathway. Characteristics of these items and the disposition strategy are discussed.
Date:
June 8, 2012
Creator:
Allender, J.; Mcclard, J. & Christopher, J.
Object Type:
Article
System:
The UNT Digital Library
Enhancing the Sensitivity to New Physics in the top-antitop Invariant Mass Distribution
We propose selection cuts on the LHC t{bar t} production sample which should enhance the sensitivity to New Physics signals in the study of the t{bar t} invariant mass distribution. We show that selecting events in which the t{bar t} object has little transverse and large longitudinal momentum enlarges the quark-fusion fraction of the sample and therefore increases its sensitivity to New Physics which couples to quarks and not to gluons. We find that systematic error bars play a fundamental role and assume a simple model for them. We check how a non-visible new particle would become visible after the selection cuts enhance its resonance bump. A final realistic analysis should be done by the experimental groups with a correct evaluation of the systematic error bars.
Date:
June 14, 2012
Creator:
Alvarez, Ezequiel & /SLAC, /Univ. Nacional San Luis
Object Type:
Article
System:
The UNT Digital Library
Simplified Models for LHC New Physics Searches
This document proposes a collection of simplified models relevant to the design of new-physics searches at the LHC and the characterization of their results. Both ATLAS and CMS have already presented some results in terms of simplified models, and we encourage them to continue and expand this effort, which supplements both signature-based results and benchmark model interpretations. A simplified model is defined by an effective Lagrangian describing the interactions of a small number of new particles. Simplified models can equally well be described by a small number of masses and cross-sections. These parameters are directly related to collider physics observables, making simplified models a particularly effective framework for evaluating searches and a useful starting point for characterizing positive signals of new physics. This document serves as an official summary of the results from the 'Topologies for Early LHC Searches' workshop, held at SLAC in September of 2010, the purpose of which was to develop a set of representative models that can be used to cover all relevant phase space in experimental searches. Particular emphasis is placed on searches relevant for the first {approx} 50-500 pb{sup -1} of data and those motivated by supersymmetric models. This note largely summarizes material posted …
Date:
June 1, 2012
Creator:
Alves, Daniele; Arkani-Hamed, Nima; Arora, Sanjay; Bai, Yang; Baumgart, Matthew; Berger, Joshua et al.
Object Type:
Article
System:
The UNT Digital Library
Mid-Atlantic Wind - Overcoming the Challenges
This study, supported by the US Department of Energy, Wind Powering America Program, Maryland Department of Natural Resources and Chesapeake Bay Foundation, analyzed barriers to wind energy development in the Mid-Atlantic region along with options for overcoming or mitigating them. The Mid-Atlantic States including Delaware, Maryland, North Carolina and Virginia, have excellent wind energy potential and growing demand for electricity, but only two utility-scale projects have been installed to date. Reasons for this apathetic development of wind resources were analyzed and quantified for four markets. Specific applications are: 1) Appalachian mountain ridgeline sites, 2) on coastal plains and peninsulas, 3) at shallow water sites in Delaware and Chesapeake Bays, Albemarle and Pamlico Sounds, and 4) at deeper water sites off the Atlantic coast. Each market has distinctly different opportunities and barriers. The primary barriers to wind development described in this report can be grouped into four categories; state policy and regulatory issues, wind resource technical uncertainty, economic viability, and public interest in environmental issues. The properties of these typologies are not mutually independent and do interact. The report concluded that there are no insurmountable barriers to land-based wind energy projects and they could be economically viable today. Likewise potential sites …
Date:
June 29, 2012
Creator:
Ancona, Daniel F., III; George, Kathryn E.; Sparling, Lynn; Buckheit, Bruce C.; LoBue, Daniel & Bowers, and Richard P.
Object Type:
Report
System:
The UNT Digital Library