Language

Electromagnetic ''Particle-in-Cell'' Plasma Simulation (open access)

Electromagnetic ''Particle-in-Cell'' Plasma Simulation

''PIC'' simulation tracks particles through electromagnetic fields calculated self-consistently from the charge and current densities of the particles themselves, external sources, and boundaries. Already used extensively in plasma physics, such simulations have become useful in the design of accelerators and their r.f. sources. 5 refs.
Date: April 22, 1985
Creator: Langdon, A. B.
Object Type: Article
System: The UNT Digital Library
Method of recovery of alkali-metal constituents from coal-conversion residues. [Patent application] (open access)

Method of recovery of alkali-metal constituents from coal-conversion residues. [Patent application]

A coal gasification operation or similar conversion process is carried out in the presence of an alkali metal-containing catalyst producing char particles containing alkali metal residues. Alkali metal constituents are recovered from the particles by burning the particles to increase their size and density and then leaching the particles of increased size and density with water, to extract the water-soluble alkali metal constituents.
Date: April 22, 1981
Creator: unknown
Object Type: Patent
System: The UNT Digital Library
ac-resistance-measuring instrument (open access)

ac-resistance-measuring instrument

An auto-ranging ac resistance measuring instrument for remote measurement of the resistance of an electrical device or circuit connected to the instrument includes a signal generator which generates an ac excitation signal for application to a load, including the device and the transmission line, a monitoring circuit which provides a digitally encoded signal representing the voltage across the load, and a microprocessor which operates under program control to provide an auto-ranging function by which range resistance is connected in circuit with the load to limit the load voltage to an acceptable range for the instrument, and an auto-compensating function by which compensating capacitance is connected in shunt with the range resistance to compensate for the effects of line capacitance.
Date: April 22, 1981
Creator: Hof, P. J.
Object Type: Patent
System: The UNT Digital Library
Dissipative Cryogenic Filters with Zero DC Resistance (open access)

Dissipative Cryogenic Filters with Zero DC Resistance

The authors designed, implemented and tested cryogenic RF filters with zero DC resistance, based on wires with a superconducting core inside a resistive sheath. The superconducting core allows low frequency currents to pass with negligible dissipation. Signals above the cutoff frequency are dissipated in the resistive part due to their small skin depth. The filters consist of twisted wire pairs shielded with copper tape. Above approximately 1 GHz, the attenuation is exponential in {radical}{omega}, as typical for skin depth based RF filters. By using additional capacitors of 10 nF per line, an attenuation of at least 45 dB above 10 MHz can be obtained. Thus, one single filter stage kept at mixing chamber temperature in a dilution refrigerator is sufficient to attenuate room temperature black body radiation to levels corresponding to 10 mK above about 10 MHz.
Date: April 22, 2008
Creator: Bluhm, Hendrik; Moler, Kathryn A. & /Stanford U., Appl. Phys. Dept
Object Type: Article
System: The UNT Digital Library
Information Resources in High-Energy Physics: Surveying the Present Landscape and Charting the Future Course (open access)

Information Resources in High-Energy Physics: Surveying the Present Landscape and Charting the Future Course

Access to previous results is of paramount importance in the scientific process. Recent progress in information management focuses on building e-infrastructures for the optimization of the research workflow, through both policy-driven and user-pulled dynamics. For decades, High-Energy Physics (HEP) has pioneered innovative solutions in the field of information management and dissemination. In light of a transforming information environment, it is important to assess the current usage of information resources by researchers and HEP provides a unique test-bed for this assessment. A survey of about 10% of practitioners in the field reveals usage trends and information needs. Community-based services, such as the pioneering arXiv and SPIRES systems, largely answer the need of the scientists, with a limited but increasing fraction of younger users relying on Google. Commercial services offered by publishers or database vendors are essentially unused in the field. The survey offers an insight into the most important features that users require to optimize their research workflow. These results inform the future evolution of information management in HEP and, as these researchers are traditionally 'early adopters' of innovation in scholarly communication, can inspire developments of disciplinary repositories serving other communities.
Date: April 22, 2008
Creator: Gentil-Beccot, Anne; Mele, Salvatore; Holtkamp, Annette; O'Connell, Heath B. & Brooks, Travis C.
Object Type: Article
System: The UNT Digital Library
Observation of B^+\to\eta\rho^+ and Search for B^0 Decays to\eta^\prime\eta, \eta\pi^0, \eta^\prime\pi^0, and \omega\pi^0 (open access)

Observation of B^+\to\eta\rho^+ and Search for B^0 Decays to\eta^\prime\eta, \eta\pi^0, \eta^\prime\pi^0, and \omega\pi^0

The authors present measurements of branching fractions for five B-meson decays to two-body charmless final states. The data, collected with the BABAR detector at the Stanford Linear Accelerator Center, represent 459 million B{bar B} pairs. The results for branching fractions are, in units of 10{sup -6} (upper limits at 90% C.L.): {Beta}(B{sup +} {yields} {eta}{rho}{sup +}) = 9.9 {+-} 1.2 {+-} 0.8, {Beta}(B{sup 0} {yields} {eta}{prime}{eta}) = 0.5 {+-} 0.4 {+-} 0.1 (< 1.2), {Beta}(B{sup 0} {yields} {eta}{pi}{sup 0}) = 0.9 {+-} 0.4 {+-} 0.1 (< 1.5), {Beta}(B{sup 0} {yields} {eta}{prime}{pi}{sup 0}) = 0.9 {+-} 0.4 {+-} 0.1 (< 1.5), and {Beta}(B{sup 0}{sup 0} {yields} {omega}{pi}{sup 0}) = {eta}{rho}{sup +} mode, they measure the charge asymmetry {Alpha}{sub ch} (B{sup +} {yields} {eta}{rho}{sup +}) = 0.13 {+-} 0.11 {+-} 0.02.
Date: April 22, 2008
Creator: Aubert, Bernard; Bona, Marcella; Karyotakis, Y.; Lees, J. P.; Poireau, V.; Prencipe, E. et al.
Object Type: Article
System: The UNT Digital Library
ATCA for Machines-- Advanced Telecommunications Computing Architecture (open access)

ATCA for Machines-- Advanced Telecommunications Computing Architecture

The Advanced Telecommunications Computing Architecture is a new industry open standard for electronics instrument modules and shelves being evaluated for the International Linear Collider (ILC). It is the first industrial standard designed for High Availability (HA). ILC availability simulations have shown clearly that the capabilities of ATCA are needed in order to achieve acceptable integrated luminosity. The ATCA architecture looks attractive for beam instruments and detector applications as well. This paper provides an overview of ongoing R&D including application of HA principles to power electronics systems.
Date: April 22, 2008
Creator: Larsen, R.S.
Object Type: Article
System: The UNT Digital Library
Testing the Standard Model with Radiative Penguin Decays at BaBar (open access)

Testing the Standard Model with Radiative Penguin Decays at BaBar

The author discusses two recent results in b {yields} s{gamma} decays from BABAR. The first is a measurement of the branching fraction and photon energy spectrum in the B meson frame of the decay B {yields} X{sub s{gamma}}. The second result probes the photon polarization via time-dependent CP violation in neutral B decays to K*{sup 0}{gamma}.
Date: April 22, 2008
Creator: Tuggle, J
Object Type: Article
System: The UNT Digital Library
Suzaku Observation of TeV Blazar the 1ES 1218+304: Clues on Particle Acceleration in an Extreme TeV Blazar (open access)

Suzaku Observation of TeV Blazar the 1ES 1218+304: Clues on Particle Acceleration in an Extreme TeV Blazar

We observed the TeV blazar 1ES 1218+304 with the X-ray astronomy satellite Suzaku in May 2006. At the beginning of the two-day continuous observation, we detected a large flare in which the 5-10 keV flux changed by a factor of {approx}2 on a timescale of 5 x 10{sup 4} s. During the flare, the increase in the hard X-ray flux clearly lagged behind that observed in the soft X-rays, with the maximum lag of 2.3 x 10{sup 4} s observed between the 0.3?1 keV and 5?10 keV bands. Furthermore we discovered that the temporal profile of the flare clearly changes with energy, being more symmetric at higher energies. From the spectral fitting of multi-wavelength data assuming a one-zone, homogeneous synchrotron self-Compton model, we obtain B {approx} 0.047 G, emission region size R = 3.0 x 10{sup 16} cm for an appropriate beaming with a Doppler factor of {delta} = 20. This value of B is in good agreement with an independent estimate through the model fit to the observed time lag ascribing the energy-dependent variability to differential acceleration timescale of relativistic electrons provided that the gyro-factor {zeta} is 10{sup 5}.
Date: April 22, 2008
Creator: Sato, R.; Kataoka, J.; Takahashi, T.; Madejski, G. M.; Rugamer, S. & Wagner, S. J.
Object Type: Article
System: The UNT Digital Library
Conduct of Operations Applicability Matrix for CMELS Moderate Hazard Facilities at LLNL Site 300 (open access)

Conduct of Operations Applicability Matrix for CMELS Moderate Hazard Facilities at LLNL Site 300

None
Date: April 22, 2008
Creator: Gregg, H R
Object Type: Report
System: The UNT Digital Library
Improved Measurement of the CKM Angle gamma in B^-+ to D^(*) K^(*)-+Decays with a Dalitz Plot Analysis of D Decays to K_S^0 pi+ pi- and K_S^0 K+ K- (open access)

Improved Measurement of the CKM Angle gamma in B^-+ to D^(*) K^(*)-+Decays with a Dalitz Plot Analysis of D Decays to K_S^0 pi+ pi- and K_S^0 K+ K-

We report on an improved measurement of the Cabibbo-Kobayashi-Maskawa CP-violating phase {gamma} through a Dalitz plot analysis of neutral D meson decays to K{sub s}{sup 0}{pi}{sup +}{pi}{sup -} and K{sub s}{sup 0}K{sup +}K{sup -} produced in the processes B{sup {-+}} {yields} DK{sup {-+}}, B{sup {-+}} {yields} D* K{sup {-+}} with D* {yields} D{pi}{sup 0}, D{gamma}, and B{sup {-+}} {yields} DK*{sup {-+}} with K8{sup {-+}} {yields} K{sub S}{sup 0}{pi}{sup {-+}}. Using a sample of 383 million B{bar B} pairs collected by the BABAR detector, we measure {gamma} = (76 {+-} 22 {+-} 5{+-} 5){sup o} (mod 180{sup o}), where the first error is statistical, the second is the experimental systematic uncertainty and the third reflects the uncertainty on the description of the Dalitz plot distributions. The corresponding two standard deviation region is 29{sup o} < {gamma} < 122{sup o}. This result has a significance of direct CP violation ({gamma} {ne} 0) of 3.0 standard deviations.
Date: April 22, 2008
Creator: Aubert, B.
Object Type: Article
System: The UNT Digital Library
Submittal of Final Post-Closure Inspection Letter Report for Corrective Action Units on the Nevada Test Site (open access)

Submittal of Final Post-Closure Inspection Letter Report for Corrective Action Units on the Nevada Test Site

None
Date: April 22, 2008
Creator: National Security Technologies, LLC
Object Type: Report
System: The UNT Digital Library
Development of Low Cost Total Energy Exchange Devices for Reducing Building Energy Consumption (open access)

Development of Low Cost Total Energy Exchange Devices for Reducing Building Energy Consumption

The primary goal of this program is to develop a commercially viable enthalpy exchangers that exhibits performance comparable to state-of-the-art exchangers, meets flammability test standards, supports no biological growth, maintains mechanical integrity for a 10 year life (typical of competitive warrantees) and exhibits a total media raw material cost of approximately 1/5 of that of the competition. The first three program tasks were devoted to: (1) gathering background information on competitors and their methods of manufacturing; (2) establishing experimental and evaluation procedures for the program; (3) identifying potential desiccants, supports and binders to be tested; (4) preparing matrix combinations on a laboratory scale; (5) testing component combinations for equilibrium moisture uptakes at different relative humidities (isotherms) and dynamic moisture adsorption rates; (6) using media adsorption properties to models to predict exchanger performance; (7) estimating ease of manufacture and finished wheel costs; and (8) calculating raw material, wheel and cassette costs based on the best media formulations. Since the rotary enthalpy exchangers have high rotational speeds, uptake rate is at least as important as equilibrium moisture uptake. Therefore, a procedure and apparatus were developed to determine adsorption rate so that the Lewis number (the ratio of mass transfer resistance to heat …
Date: April 22, 2002
Creator: Belding, William; Collier, R. & Worek, William
Object Type: Report
System: The UNT Digital Library
From Loops to Trees By-passing Feynman's Theorem (open access)

From Loops to Trees By-passing Feynman's Theorem

We derive a duality relation between one-loop integrals and phase-space integrals emerging from them through single cuts. The duality relation is realized by a modification of the customary + i0 prescription of the Feynman propagators. The new prescription regularizing the propagators, which we write in a Lorentz covariant form, compensates for the absence of multiple cut contributions that appear in the Feynman Tree Theorem. The duality relation can be applied to generic one-loop quantities in any relativistic, local and unitary field theories. It is suitable for applications to the analytical calculation of one-loop scattering amplitudes, and to the numerical evaluation of cross-sections at next-to-leading order.
Date: April 22, 2008
Creator: Catani, Stefano; Gleisberg, Tanju; Krauss, Frank; Rodrigo, German & Winter, Jan-Christopher
Object Type: Report
System: The UNT Digital Library
Real-time Data Access Monitoring in Distributed, Multi-petabyte Systems (open access)

Real-time Data Access Monitoring in Distributed, Multi-petabyte Systems

Petascale systems are in existence today and will become common in the next few years. Such systems are inevitably very complex, highly distributed and heterogeneous. Monitoring a petascale system in real-time and understanding its status at any given moment without impacting its performance is a highly intricate task. Common approaches and off-the-shelf tools are either unusable, do not scale, or severely impact the performance of the monitored servers. This paper describes unobtrusive monitoring software developed at Stanford Linear Accelerator Center (SLAC) for a highly distributed petascale production data set. The paper describes the employed solutions, the lessons learned, the problems still to be addressed, and explains how the system can be reused elsewhere.
Date: April 22, 2008
Creator: Azemoon, Tofigh; Becla, Jacek, a=Hanushevsky, Andrew & Turri, Massimiliano
Object Type: Article
System: The UNT Digital Library
Two-dimensional Vortex Behavior in Highly Underdoped YBa_2Cu_3O_{6+x} Observed byScanning Hall Probe Microscopy (open access)

Two-dimensional Vortex Behavior in Highly Underdoped YBa_2Cu_3O_{6+x} Observed byScanning Hall Probe Microscopy

We report scanning Hall probe microscopy of highly underdoped superconducting YBa{sub 2}Cu{sub 3}O{sub 6+z} with T{sub c} ranging from 5 to 15 K which showed distinct flux bundles with less than one superconducting flux quantum ({Phi}{sub 0}) through the sample surface. The sub-{Phi}{sub 0} features occurred more frequently for lower T{sub c}, were more mobile than conventional vortices, and occurred more readily when the sample was cooled with an in-plane field component. We show that these features are consistent with kinked stacks of pancake vortices.
Date: April 22, 2008
Creator: Guikema, J.W.; Bluhm, Hendrik; /Stanford U., Appl. Phys. Dept.; Bonn, D.A.; Liang, Ruixing; Hardy, W.N. et al.
Object Type: Article
System: The UNT Digital Library
Conduct of Operations Applicability Matrix for CMELS Light Science and Industry and General Industry Facilities at LLNL Site 200 (open access)

Conduct of Operations Applicability Matrix for CMELS Light Science and Industry and General Industry Facilities at LLNL Site 200

None
Date: April 22, 2008
Creator: Cooper, G A
Object Type: Report
System: The UNT Digital Library
TEMPERATURE PREDICTION IN 3013 CONTAINERS IN K AREA MATERIAL STORAGE (KAMS) FACILITY USING REGRESSION METHODS (open access)

TEMPERATURE PREDICTION IN 3013 CONTAINERS IN K AREA MATERIAL STORAGE (KAMS) FACILITY USING REGRESSION METHODS

3013 containers are designed in accordance with the DOE-STD-3013-2004. These containers are qualified to store plutonium (Pu) bearing materials such as PuO2 for 50 years. DOT shipping packages such as the 9975 are used to store the 3013 containers in the K-Area Material Storage (KAMS) facility at Savannah River Site (SRS). DOE-STD-3013-2004 requires that a comprehensive surveillance program be set up to ensure that the 3013 container design parameters are not violated during the long term storage. To ensure structural integrity of the 3013 containers, thermal analyses using finite element models were performed to predict the contents and component temperatures for different but well defined parameters such as storage ambient temperature, PuO{sub 2} density, fill heights, weights, and thermal loading. Interpolation is normally used to calculate temperatures if the actual parameter values are different from the analyzed values. A statistical analysis technique using regression methods is proposed to develop simple polynomial relations to predict temperatures for the actual parameter values found in the containers. The analysis shows that regression analysis is a powerful tool to develop simple relations to assess component temperatures.
Date: April 22, 2008
Creator: Gupta, N
Object Type: Article
System: The UNT Digital Library
Nonlocal exchange correlation in screened-exchange densityfunctional methods (open access)

Nonlocal exchange correlation in screened-exchange densityfunctional methods

We present a systematic study on the exchange-correlationeffects in screened-exchange local density functional method. Toinvestigate the effects of the screened-exchange potential in the bandgap correction, we have compared the exchange-correlation potential termin the sX-LDA formalism with the self-energy term in the GWapproximation. It is found that the band gap correction of the sX-LDAmethod primarily comes from the downshift of valence band states,resulting from the enhancement of bonding and the increase of ionizationenergy. The band gap correction in the GW method, on the contrary, comesin large part from the increase of theconduction band energies. We alsostudied the effects of the screened-exchange potential in the totalenergy by investigating the exchange-correlation hole in comparison withquantum Monte Carlo calculations. When the Thomas-Fermi screening isused, the sX-LDA method overestimates (underestimates) theexchange-correlation hole in short (long) range. From theexchange-correlation energy analysis we found that the LDA method yieldsbetter absolute total energy than sX-LDA method.
Date: April 22, 2007
Creator: Lee, Byounghak; Wang, Lin-Wang; Spataru, Catalin D. & Louie,Steven G.
Object Type: Article
System: The UNT Digital Library
High-Level Application Framework for LCLS (open access)

High-Level Application Framework for LCLS

A framework for high level accelerator application software is being developed for the Linac Coherent Light Source (LCLS). The framework is based on plug-in technology developed by an open source project, Eclipse. Many existing functionalities provided by Eclipse are available to high-level applications written within this framework. The framework also contains static data storage configuration and dynamic data connectivity. Because the framework is Eclipse-based, it is highly compatible with any other Eclipse plug-ins. The entire infrastructure of the software framework will be presented. Planned applications and plug-ins based on the framework are also presented.
Date: April 22, 2008
Creator: Chu, P; Chevtsov, S.; Fairley, D.; Larrieu, C.; Rock, J.; Rogind, D. et al.
Object Type: Article
System: The UNT Digital Library
12.6 keV Kr K-alpha X-ray Source For High Energy Density Physics Experiments (open access)

12.6 keV Kr K-alpha X-ray Source For High Energy Density Physics Experiments

A high contrast 12.6 keV Kr K{alpha} source has been demonstrated on the petawatt-class Titan laser facility. The contrast ratio (K{alpha} to continuum) is 65, with a competitive ultra short pulse laser to x-ray conversion efficiency of 10{sup -5}. Filtered shadowgraphy indicates that the Kr K{alpha} and K{beta} x-rays are emitted from a roughly 1 x 2 mm emission volume, making this source suitable for area backlighting and scattering. Spectral calculations indicate a typical bulk electron temperature of 50-70 eV (i.e. mean ionization state 13-16), based on the observed ratio of K{alpha} to K{beta}. Kr gas jets provide a debris-free high energy K{alpha} source for time-resolved diagnosis of dense matter.
Date: April 22, 2008
Creator: Kugland, N.; Constantin, C. G.; Niemann, C.; Neumayer, P.; Chung, H.; Doppner, T. et al.
Object Type: Article
System: The UNT Digital Library
Conduct of Operations Applicability Matrix for CMELS Low Hazard Facilities at LLNL Site 200 (open access)

Conduct of Operations Applicability Matrix for CMELS Low Hazard Facilities at LLNL Site 200

None
Date: April 22, 2008
Creator: Cooper, G A
Object Type: Report
System: The UNT Digital Library
Letter Report for Waste Disposal Activities for Corrective Action Unit 127: Areas 25 and 26 Storage Tanks, Nevada Test Site, Nevada, March 2008 (open access)

Letter Report for Waste Disposal Activities for Corrective Action Unit 127: Areas 25 and 26 Storage Tanks, Nevada Test Site, Nevada, March 2008

None
Date: April 22, 2008
Creator: National Security Technologies, LLC
Object Type: Report
System: The UNT Digital Library
Framework for the systematic assessment of a material control and accounting system (open access)

Framework for the systematic assessment of a material control and accounting system

Procedures are described for the systematic assessment of a Material Control and Accounting (MC and A) system, in terms of compliance to the proposed MC and A Upgrade Rule. The applicability of these assessment procedures to specific Rule provisions is discussed. Special attention is given to the statistical performance of individual subsystems, and their vulnerability to compromise by insider collusion.
Date: April 22, 1981
Creator: Schechter, R. S. & Sacks, I. J.
Object Type: Report
System: The UNT Digital Library