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Astrophysical Gyrokinetics: Kinetic and Fluid Turbulent Cascades In Magentized Weakly Collisional Plasmas
This paper presents a theoretical framework for understanding plasma turbulence in astrophysical plasmas. It is motivated by observations of electromagnetic and density fluctuations in the solar wind, interstellar medium and galaxy clusters, as well as by models of particle heating in accretion disks. All of these plasmas and many others have turbulentmotions at weakly collisional and collisionless scales. The paper focuses on turbulence in a strong mean magnetic field. The key assumptions are that the turbulent fluctuations are small compared to the mean field, spatially anisotropic with respect to it and that their frequency is low compared to the ion cyclotron frequency. The turbulence is assumed to be forced at some system-specific outer scale. The energy injected at this scale has to be dissipated into heat, which ultimately cannot be accomplished without collisions. A kinetic cascade develops that brings the energy to collisional scales both in space and velocity. The nature of the kinetic cascade in various scale ranges depends on the physics of plasma fluctuations that exist there. There are four special scales that separate physically distinct regimes: the electron and ion gyroscales, the mean free path and the electron diffusion scale. In each of the scale ranges separated …
Date:
April 23, 2009
Creator:
A.A. Schekochihin, S.C. Cowley, W. Dorland, G.W. Hammett, G.G. Howes, E. Quataert, and T. Tatsuno
Object Type:
Report
System:
The UNT Digital Library
High performance anti-reflection coatings for broadband multi-junction solar cells
The success of bandgap engineering has made high efficiency broadband multi-junction solar cells possible with photo-response out to the band edge of Ge. Modeling has been conducted which suggests that current double layer anti-reflection coating technology is not adequate for these devices in certain cases. Approaches for the development of higher performance anti-reflection coatings are examined. A new AR coating structure based on the use of Herpin equivalent layers is presented. Optical modeling suggests a decrease in the solar weighted reflectance of over 2.5{percent} absolute as a result. This structure requires no additional optical material development and characterization because no new optical materials are necessary. Experimental results and a sensitivity analysis are presented.
Date:
February 23, 2000
Creator:
AIKEN,DANIEL J.
Object Type:
Article
System:
The UNT Digital Library
DEWATERING TREATMENT SCALE-UP TESTING RESULTS OF HANFORD TANK WASTES
This report documents CH2M HILL Hanford Group Inc. (CH2M HILL) 2007 dryer testing results in Richland, WA at the AMEC Nuclear Ltd., GeoMelt Division (AMEC) Horn Rapids Test Site. It provides a discussion of scope and results to qualify the dryer system as a viable unit-operation in the continuing evaluation of the bulk vitrification process. A 10,000 liter (L) dryer/mixer was tested for supplemental treatment of Hanford tank low-activity wastes, drying and mixing a simulated non-radioactive salt solution with glass forming minerals. Testing validated the full scale equipment for producing dried product similar to smaller scale tests, and qualified the dryer system for a subsequent integrated dryer/vitrification test using the same simulant and glass formers. The dryer system is planned for installation at the Hanford tank farms to dry/mix radioactive waste for final treatment evaluation of the supplemental bulk vitrification process.
Date:
January 23, 2008
Creator:
AR, TEDESCHI
Object Type:
Article
System:
The UNT Digital Library
Alignment strategy for the ATLAS tracker
The ATLAS experiment is a multi-purpose particle detector that will study high-energy particle collisions produced by the Large Hadron Collider. For the reconstruction of charged particles, and their production and their decay vertices, ATLAS is equipped with a sophisticated tracking system, unprecedented in size and complexity. Full exploitation of both the Inner Detector and the muon spectrometer requires an accurate alignment. The challenge of aligning the ATLAS tracking devices is discussed, and the ATLAS alignment strategy is presented and illustrated with both data and Monte Carlo results.
Date:
September 23, 2007
Creator:
ATLAS & Golling, T.
Object Type:
Article
System:
The UNT Digital Library
ATLAS TrackingEvent Data Model -- 12.0.0
In this report the event data model (EDM) relevant for tracking in the ATLAS experiment is presented. The core component of the tracking EDM is a common track object which is suited to describe tracks in the innermost tracking sub-detectors and in the muon detectors in offline as well as online reconstruction. The design of the EDM was driven by a demand for modularity and extensibility while taking into account the different requirements of the clients. The structure of the track object and the representation of the tracking-relevant information are described in detail.
Date:
July 23, 2006
Creator:
ATLAS; Akesson, F.; Atkinson, T.; Costa, M.J.; Elsing, M.; Fleischmann, S. et al.
Object Type:
Article
System:
The UNT Digital Library
Electric Reliability: Options for Electric Transmission Infrastructure Improvements
The electric utility industry is inherently capital intensive. At the same time, the industry must operate under a changing and sometimes unpredictable regulatory system at both the federal and state level. The Energy Policy Act of 2005 has set in place government activities intended to relieve congestion on the transmission system. Several factors have contributed to the lack of new transmission capacity; these are outlined within this report. This report also discusses earlier pieces of energy legislation.
Date:
December 23, 2004
Creator:
Abel, Amy
Object Type:
Report
System:
The UNT Digital Library
Electric Reliability: Options for Electric Transmission Infrastructure Improvements
The electric utility industry is inherently capital intensive. At the same time, the industry must operate under a changing and sometimes unpredictable regulatory system at both the federal and state level. The Energy Policy Act of 2005 has set in place government activities intended to relieve congestion on the transmission system. Several factors have contributed to the lack of new transmission capacity; these are outlined within this report. This report also discusses earlier pieces of energy legislation.
Date:
December 23, 2004
Creator:
Abel, Amy
Object Type:
Report
System:
The UNT Digital Library
Laboratory Studies of the Effects of Pressure and Dissolved Gas Supersaturation on Turbine-Passed Fish
The objective of this study was to examine the relative importance of pressure changes as a source of turbine-passage injury and mortality. Specific tests were designed to quantify the response of fish to rapid pressure changes typical of turbine passage, with and without the complication of the fish being acclimated to gas supersaturated water. We investigated the responses of rainbow trout (Oncorhynchus mykiss), chinook salmon (O. tshawytscha), and bluegill sunfish (Lepomis macrochirus) to these two stresses, both singly and in combination.
Date:
March 23, 2001
Creator:
Abernethy, Cary S & Amidan, Brett G
Object Type:
Report
System:
The UNT Digital Library
Laboratory Studies of the Effects of Pressure and Dissolved Gas Supersaturation on Turbine-Passed Fish
The objective of this study was to examine the relative importance of pressure changes as a source of turbine-passage injury and mortality. Specific tests were designed to quantify the response of fish to rapid pressure changes typical of turbine passage, with and without the complication of the fish being acclimated to gas supersaturated water. We investigated the responses of rainbow trout (Oncorhynchus mykiss), chinook salmon (O. tshawytscha), and bluegill sunfish (Lepomis macrochirus) to these two stresses, both singly and in combination.
Date:
March 23, 2001
Creator:
Abernethy, Cary S.; Amidan, Brett G. & Cada, G F.
Object Type:
Report
System:
The UNT Digital Library
Commodity multi-processor systems in the ATLAS level-2 trigger
Low cost SMP (Symmetric Multi-Processor) systems provide substantial CPU and I/O capacity. These features together with the ease of system integration make them an attractive and cost effective solution for a number of real-time applications in event selection. In ATLAS the authors consider them as intelligent input buffers (active ROB complex), as event flow supervisors or as powerful processing nodes. Measurements of the performance of one off-the-shelf commercial 4-processor PC with two PCI buses, equipped with commercial FPGA based data source cards (microEnable) and running commercial software are presented and mapped on such applications together with a long-term program of work. The SMP systems may be considered as an important building block in future data acquisition systems.
Date:
May 23, 2000
Creator:
Abolins, M.; Blair, R.; Bock, R.; Bogaerts, A.; Dawson, J.; Ermoline, Y. et al.
Object Type:
Article
System:
The UNT Digital Library
Feedback damper system for quadrupole oscillations after transition at RHIC.
The heavy ion beam at RHIC undergoes strong quadrupole oscillations just after it crosses transition, which leads to an increase in bunch length making rebucketing less effective. A feedback system was built to damp these quadrupole oscillations and in this paper the characteristics of the system and the results obtained are presented and discussed.
Date:
June 23, 2008
Creator:
Abreu, N.; Blaskiewicz, M.; Brennan, J. M. & Schultheiss, C.
Object Type:
Article
System:
The UNT Digital Library
The effect of head-on beam-beam compensation on the stochastic boundaries and particle diffusion in RHIC.
To compensate the effects from the head-on beam-beam interactions in the polarized proton operation in the Relativistic Heavy Ion Collider (RHIC), an electron lens (elens) is proposed to collide head-on with the proton beam. We used an extended version of SixTrack for multiparticle beam-beam simulation in order to study the effect of the e-lens on the stochastic boundary and also on diffusion. The stochastic boundary was analyzed using Lyapunov exponents and the diffusion was characterized as the increase in the rms spread of the action. For both studies the simulations were performed with and without the e-lens and with full and partial compensation. Using the simulated values of the diffusion an attempt to calculate the emittance growth rate is presented.
Date:
June 23, 2008
Creator:
Abreu,N.; Beebe-Wang, J.; FischW; Luo, Y. & Robert-Demolaize, G.
Object Type:
Article
System:
The UNT Digital Library
Energy loss of coasting gold ions and deuterons in RHIC.
The total energy loss of coasting gold ion beams was measured at RHIC at two energies, corresponding to a gamma of 75.2 and 107.4. We describe the experiment and observations and compare the measured total energy loss with expectations from ionization losses at the residual gas, the energy loss due to impedance and synchrotron radiation. We find that the measured energy losses are below what is expected from free space synchrotron radiation. We believe that this shows evidence for suppression of synchrotron radiation which is cut off at long wavelength by the presence of the conducting beam pipe.
Date:
June 23, 2008
Creator:
Abreu,N.; Blaskiewicz, M.; Brown, K.A.; Butler, J.J.; FischW; Harvey, M. et al.
Object Type:
Article
System:
The UNT Digital Library
Co-ordination of the International Network of Nuclear Structure and Decay Data Evaluators; Summary Report of an IAEA Technical Meeting
The IAEA Nuclear Data Section convened the 18th meeting of the International Network of Nuclear Structure and Decay Data Evaluators at the IAEA Headquarters, Vienna, 23 to 27 March 2009. This meeting was attended by 22 scientists from 14 Member States, plus IAEA staff, concerned with the compilation, evaluation and dissemination of nuclear structure and decay data. A summary of the meeting, recommendations/conclusions, data centre reports, and various proposals considered, modified and agreed by the participants are contained within this document. The International Network of Nuclear Structure and Decay Data (NSDD) Evaluators holds biennial meetings under the auspices of the IAEA, and consists of evaluation groups and data service centres in several countries. This network has the objective of providing up-to-date nuclear structure and decay data for all known nuclides by evaluating all existing experimental data. Data resulting from this international evaluation collaboration is included in the Evaluated Nuclear Structure Data File (ENSDF) and published in the journals Nuclear Physics A and Nuclear Data Sheets (NDS).
Date:
March 23, 2009
Creator:
Abriola, D. & Tuli, J.
Object Type:
Report
System:
The UNT Digital Library
International Law and the Preemptive Use of Force Against Iraq
None
Date:
September 23, 2002
Creator:
Ackerman, David M.
Object Type:
Report
System:
The UNT Digital Library
B physics: measurement of the j/psi meson and b-hadron production cross sections in p anti-p collisions at s**(1/2) = 1960 gev
The authors present a new measurement of the inclusive and differential production cross sections of J/{psi} mesons and b-hadrons in proton-antiproton collisions at {radical}s = 1960 GeV. The data correspond to an integrated luminosity of 39.7 pb{sup -1} collected by the CDF Run II detector. They find the integrated cross section for inclusive J/{psi} production for all transverse momenta from 0 to 20 GeV/c in the rapidity range |y| < 0.6 to be 4.08 {+-} 0.02(stat){sub -0.33}{sup +0.36}(syst) {mu}b. They separate the fraction of J/{psi} events from the decay of the long-lived b-hadrons using the lifetime distribution in all events with p{sub T}(J/{psi}) > 1.25 GeV/c. They find the total cross section for b-hadrons, including both hadrons and anti-hadrons, decaying to J/{psi} with transverse momenta greater than 1.25 GeV/c in the rapidity range |y(J/{psi})| < 0.6, is 0.330 {+-} 0.005(stat){sub -0.033}{sup +0.036}(syst) {mu}b. Using a Monte Carlo simulation of the decay kinematics of b-hadrons to all final states containing a J/{psi}, they extract the first measurement of the total single b-hadron cross section down to zero transverse momentum at {radical}s = 1960 GeV. They find the total single b-hadron cross section integrated over all transverse momenta for b-hadrons in the …
Date:
December 23, 2004
Creator:
Acosta, D.
Object Type:
Article
System:
The UNT Digital Library
Electroweak physics: measurement of the forward-backward charge asymmetry of electron-positron pairs in p anti-p collisions at s**(1/2) = 1.96 tev
We report a measurement of the forward-backward charge asymmetry of electrons from W boson decays in p{bar p} collisions at {radical}s = 1.96 TeV using a data sample of 170 pb{sup -1} collected by the Collider Detector at Fermilab. The asymmetry is measured as a function of electron rapidity and transverse energy and provides new input on the momentum fraction dependence of the u and d quark parton distribution functions within the proton.
Date:
February 23, 2005
Creator:
Acosta, D.
Object Type:
Report
System:
The UNT Digital Library
Leptoquark searches at the Tevatron
The authors report on searches for leptoquarks using approximately 100 pb {sup -1} of data collected by CDF and DO during Run I at the Tevatron. They also present searches for resonantly-produced leptoquarks that arise in technicolor models. Prospects for future leptoquark searches using Run II data are also discussed.
Date:
June 23, 2000
Creator:
Acosta, Darin E.
Object Type:
Article
System:
The UNT Digital Library
Hadronization geometry and charge-dependent two-particlecorrelation on momentum subspace (eta, phi) in Au-Au collisions atsqrt(sNN) = 130 GeV
We present the first measurements of charge-dependent two-particle correlations on momentum-space difference variables {eta}{sub 1}-{eta}{sub 2} (pseudorapidity) and {phi}{sub 1}-{phi}{sub 2} (azimuth) for primary charged hadrons with transverse momentum 0.15 {le} p{sub t} {le} 2 GeV/c and |{eta}| {le} 1.3 from Au-Au collisions at {radical}s{sub NN} = 130 GeV. We observe correlation structures not predicted by theory but consistent with evolution of hadron emission geometry with increasing centrality from one-dimensional fragmentation of color strings to higher-dimensional fragmentation of a hadron-opaque bulk medium.
Date:
September 23, 2004
Creator:
Adams, J.; Aggarwal, M. M.; Ahammed, Z.; Amonett, J.; Anderson, B. D.; Arkhipkin, D. et al.
Object Type:
Article
System:
The UNT Digital Library
Performance of particle in cell methods on highly concurrent computational architectures
Particle in cell (PIC) methods are effective in computing Vlasov-Poisson system of equations used in simulations of magnetic fusion plasmas. PIC methods use grid based computations, for solving Poisson’s equation or more generally Maxwell’s equations, as well as Monte-Carlo type methods to sample the Vlasov equation. The presence of two types of discretizations, deterministic field solves and Monte-Carlo methods for the Vlasov equation, pose challenges in understanding and optimizing performance on today large scale computers which require high levels of concurrency. These challenges arises from the need to optimize two very different types of processes and the interactions between them. Modern cache based high-end computers have very deep memory hierarchies and high degrees of concurrency which must be utilized effectively to achieve good performance. The effective use of these machines requires maximizing concurrency by eliminating serial or redundant work and minimizing global communication. A related issue is minimizing the memory traffic between levels of the memory hierarchy because performance is often limited by the bandwidths and latencies of the memory system. This paper discusses some of the performance issues, particularly in regard to parallelism, of PIC methods. The gyrokinetic toroidal code (GTC) is used for these studies and a new …
Date:
September 23, 2009
Creator:
Adams, M. F.; Ethier, S. & Wichmann, N.
Object Type:
Report
System:
The UNT Digital Library
Tank Characterization Report for Double Shell Tank (DST) 241-AN-107
This report interprets information about the tank answering a series of six questions covering areas such as information drivers, tank history, tank comparisons, disposal implications, data quality and quantity, and unique aspects of the tank.
Date:
March 23, 2000
Creator:
Adams, M. R.
Object Type:
Report
System:
The UNT Digital Library
Lebanon: Background and U.S. Relations
This report provides an overview of Lebanese politics, recent events in Lebanon, and current issues in U.S.-Lebanon relations and will be updated to reflect major developments.
Date:
July 23, 2009
Creator:
Addis, Casey L.
Object Type:
Report
System:
The UNT Digital Library
Biomass and Biofuels: Technology and Economic Overview
Presentation on biomass and biofuels technology and economics presented at Pacific Northwest National Laboratory, May 23, 2007.
Date:
May 23, 2007
Creator:
Aden, Andy
Object Type:
Presentation
System:
The UNT Digital Library
Geometrically induced metastability and holography
We construct metastable configurations of branes and anti-branes wrapping 2-spheres inside local Calabi-Yau manifolds and study their large N duals. These duals are Calabi-Yau manifolds in which the wrapped 2-spheres have been replaced by 3-spheres with flux through them, and supersymmetry is spontaneously broken. The geometry of the non-supersymmetric vacuum is exactly calculable to all orders of the't Hooft parameter, and to the leading order in 1/N. The computation utilizes the same matrix model techniques that were used in the supersymmetric context. This provides a novel mechanism for breaking supersymmetry in the context of flux compactifications.
Date:
October 23, 2006
Creator:
Aganagic, Mina; Aganagic, Mina; Beem, Christopher; Seo, Jihye & Vafa, Cumrun
Object Type:
Article
System:
The UNT Digital Library