76 Matching Results

Search Results

Results: 1 - 24 next
open access

Progress with Tevatron Electron Lenses

Description: No Description Available.
Date: September 13, 2007
Creator: Kamerdzhiev, V.; Alexahin, Y.; Kuznetsov, G. F.; Shiltsev, V. D. & Zhang, X.
Partner: UNT Libraries Government Documents Department
open access

New Equalizers for Antiproton Stochastic Cooling at Fermilab

Description: In the continuous effort to improve antiproton stacking rate, a new type of equalizers has been developed and installed in antiproton accumulator. The R&D of these new equalizers is described in this paper. Equalizers are used in Fermilab antiproton stochastic cooling to compensate frequency response of the cooling system. Usually both amplitude and phase compensations are needed. However in most cases it is difficult to achieve a satisfactory compensation for both because of their interdep… more
Date: September 13, 2007
Creator: Lebedev, V. A.; Pasquinelli, R. J. & Sun, D.
Partner: UNT Libraries Government Documents Department
open access

Exp6-polar thermodynamics of dense supercritical water

Description: We introduce a simple polar fluid model for the thermodynamics of dense supercritical water based on a Buckingham (exp-6) core and point dipole representation of the water molecule. The proposed exp6-polar thermodynamics, based on ideas originally applied to dipolar hard spheres, performs very well when tested against molecular dynamics simulations. Comparisons of the model predictions with experimental data available for supercritical water yield excellent agreement for the shock Hugoniot, iso… more
Date: December 13, 2007
Creator: Bastea, S & Fried, L E
Partner: UNT Libraries Government Documents Department
open access

Soft Phonons in (delta)-Phase Plutonium Near the (delta)-(alpha)' Transition

Description: Plutonium and its alloys exhibit complex phase diagrams that imply anomalous lattice dynamics near phase stability boundaries. Specifically, the TA [111] phonon branch in Ga-stabilized {delta}-Pu at room temperature shows a pronounced soft mode at the zone boundary, which suggests a possible connection to the martensitic transformation from the fcc {delta}-phase to the monoclinic {alpha}{prime}-phase at low temperatures. This work is a study of the lattice dynamics of this system by x-ray therm… more
Date: September 13, 2007
Creator: Xu, R; Wong, J; Zshack, P; Hong, H & Chiang, T
Partner: UNT Libraries Government Documents Department
open access

Towards a Sustainable Energy Balance: Progressive Efficiency and the Return of Energy Conservation

Description: We argue that a primary focus on energy efficiency may not be sufficient to slow (and ultimately reverse) the growth in total energy consumption and carbon emissions. Instead, policy makers need to return to an earlier emphasis on"conservation," with energy efficiency seen as a means rather than an end in itself. We briefly review the concept of"intensive" versus"extensive" variables (i.e., energy efficiency versus energy consumption), and why attention to both con… more
Date: August 13, 2007
Creator: Diamond, Rick; Harris, Jeff; Diamond, Rick; Iyer, Maithili; Payne, Christopher; Blumstein, Carl et al.
Partner: UNT Libraries Government Documents Department
open access

The silicon microstrip sensors of the ATLAS semiconductor tracker

Description: This paper describes the AC-coupled, single-sided, p-in-n silicon microstrip sensors used in the Semiconductor Tracker (SCT) of the ATLAS experiment at the CERN Large Hadron Collider (LHC). The sensor requirements, specifications and designs are discussed, together with the qualification and quality assurance procedures adopted for their production. The measured sensor performance is presented, both initially and after irradiation to the fluence anticipated after 10 years of LHC operation. The … more
Date: April 13, 2007
Creator: Collaboration, ATLAS SCT & Spieler, Helmuth G.
Partner: UNT Libraries Government Documents Department
open access

Toward Fast Computation of Dense Image Correspondence on the GPU

Description: Large-scale video processing systems are needed to support human analysis of massive collections of image streams. Video, from both current small-format and future large-format camera systems, constitutes the single largest data source of the near future, dwarfing the output of all other data sources combined. A critical component to further advances in the processing and analysis of such video streams is the ability to register successive video frames into a common coordinate system at the pix… more
Date: August 13, 2007
Creator: Duchaineau, M; Cohen, J & Vaidya, S
Partner: UNT Libraries Government Documents Department
open access

Spatiotemporal variations in growing season exchanges of CO2, H2O,and sensible heat in agricultural fields of the Southern GreatPlains

Description: Climate, vegetation cover, and management create fine-scaleheterogeneity in unirrigated agricultural regions, with important but notwell-quantified consequences for spatial and temporal variations insurface CO2, water, and heat fluxes. We measured eddy covariance fluxesin seven agricultural fields--comprising winter wheat, pasture, andsorghum--in the U.S. Southern Great Plains (SGP) during the 2001-2003growing seasons. Land-cover was the dominant source of variation insurface fluxes, with 50-10… more
Date: June 13, 2007
Creator: Fischer, Marc L.; Billesbach, David P.; Berry, Joseph A.; Riley,William J. & Torn, Margaret S.
Partner: UNT Libraries Government Documents Department
open access

CHARACTERIZATION OF A HIGH CURRENT INDUCTION ACCELERATOR ELECTRON BEAM VIA OPTICAL TRANSITION RADIATION FROM DIELECTRIC FOILS

Description: Traditionally, thin metal foils are employed for optical transition radiation (OTR) beam diagnostics but the possibility of shorting accelerator insulating surfaces and modifying accelerating fields are concerns. The successful utilization of dielectric foils in place of metal ones could alleviate these issues but necessitates more understanding of the OTR data for inferring desired beam parameters because of the dielectric's finite permittivity. Additionally, the temperature dependence of the … more
Date: June 13, 2007
Creator: Tang, V; Brown, C & Houck, T
Partner: UNT Libraries Government Documents Department
open access

Soft X-ray Mirrors for the Linac Coherent Light Source

Description: The Linac Coherent Light Source (LCLS) is a 0.15-1.5 nm wavelength free-electron laser (FEL) being constructed at the Stanford Linear Accelerator Center (SLAC) by a multi-institution consortium, including Lawrence Livermore National Laboratory (LLNL). One of LLNL's responsibilities involves the design and construction of two grazing-incidence mirror systems whose primary intent is to reduce radiation levels in the experimental halls by separating the FEL beam from unwanted high-energy photons. … more
Date: August 13, 2007
Creator: Pivovaroff, M. J.; Bionta, R. M.; Mccarville, T. J.; Soufli, R. & Stefan, P. M.
Partner: UNT Libraries Government Documents Department
open access

Intrinsic and Extrinsic Chemical and Isotopic Tracers for Characterization Of Groundwater Systems

Description: In many regions, three dimensional characterization of the groundwater regime is limited by coarse well spacing or borehole lithologic logs of low quality. However, regulatory requirements for drinking water or site remediation may require collection of extensive chemical and water quality data from existing wells. Similarly, for wells installed in the distant past, lithologic logs may not be available, but the wells can be sampled for chemical and isotopic constituents. In these situations, a … more
Date: September 13, 2007
Creator: Moran, J E; Singleton, M J; Carle, S F & Esser, B K
Partner: UNT Libraries Government Documents Department
open access

Micropatterning of Gold Substrates Based on Poly(Propylene Sulfide-Bl-Ethylene Glycol), (Pps-Peg) Background Passivation and the Molecular-Assembly Patterning by Lift-Off (Mapl) Technique

Description: Poly(propylene sulfide-bl-ethylene glycol) (PPS-PEG) is an amphiphilic block copolymer that spontaneously adsorbs onto gold from solution. This results in the formation of a stable polymeric layer that renders the surface protein resistant when an appropriate architecture is chosen. The established molecular assembly patterning by lift-off (MAPL) technique can convert a prestructured resist film into a pattern of biointeractive chemistry and a noninteractive background. Employing the MAPL techn… more
Date: November 13, 2007
Creator: Feller, L.; Bearinger, J. P.; Wu, L.; Hubbell, J. A.; Textor, M. & Tosatti, S.
Partner: UNT Libraries Government Documents Department
open access

SHOCK INITIATION EXPERIMENTS ON PBX 9501 EXPLOSIVE AT PRESSURES BELOW 3 GPa WITH ASSOCIATED IGNITION AND GROWTH MODELING

Description: Shock initiation experiments on the explosive PBX 9501 (95% HMX, 2.5% estane, and 2.5% nitroplasticizer by weight) were performed at pressures below 3 GPa to obtain in-situ pressure gauge data, run-distance-to-detonation thresholds, and Ignition and Growth modeling parameters. Propellant driven gas guns (101 mm and 155 mm) were utilized to initiate the PBX 9501 explosive with manganin piezoresistive pressure gauge packages placed between sample slices. The run-distance-to-detonation points on t… more
Date: June 13, 2007
Creator: Chidester, S K; Thompson, D G; Vandersall, K S; Idar, D J; Tarver, C M; Garcia, F et al.
Partner: UNT Libraries Government Documents Department
open access

DYNAMIC LOADING OF TEFLON AT 200?C

Description: Dynamic loading experiments were performed on inert Teflon (Polytetrafluoroethylene) samples, initially heated to the temperature of 200 C, to test its behavior under these conditions for its use in other heated experiments. Tests were performed in the 100 mm diameter bore propellant driven gas gun with piezo-resistive manganin pressure gauges imbedded into the samples to measure loading pressures. Experimental data provided new information on the shock velocity - particle velocity relationship… more
Date: June 13, 2007
Creator: Urtiew, P A; Forbes, J W; Tarver, C M; Vandersall, K S & Garcia, F
Partner: UNT Libraries Government Documents Department
open access

Editorial

Description: The Tenth International Conference on Accelerator Mass Spectrometry (AMS-10) was held from September 5-10 at the University of California, Berkeley campus. The conference attracted 305 attendees from 26 countries who gave 144 platform presentations and presented a total of 170 posters. The conference opened with a special tribute to the late Roy Middleton, which was followed by a companion session on 'ion sourcery'. A plenary talk by Wally Broecker on his '53 years in the Radiocarbon Trenches',… more
Date: August 13, 2007
Creator: Knezovich, J; Brown, T; Buchholz, B; Finkel, B; Guilderson, T; Kashgarian, M et al.
Partner: UNT Libraries Government Documents Department
open access

Beam Based Measurements for Stochastic Cooling Systems at Fermilab

Description: Improvement of antiproton stacking rates has been pursued for the last twenty years at Fermilab. The last twelve months have been dedicated to improving the computer model of the Stacktail system. The production of antiprotons encompasses the use of the entire accelerator chain with the exception of the Tevatron. In the Antiproton Source two storage rings, the Debuncher and Accumulator are responsible for the accumulation of antiprotons in quantities that can exceed 2 x 10{sup 12}, but more rou… more
Date: September 13, 2007
Creator: Lebedev, V. A.; Pasquinelli, R. J. & Werkema, S. J.
Partner: UNT Libraries Government Documents Department
open access

Electrostatic Modeling of Vacuum Insulator Triple Junctions

Description: A comprehensive matrix of 60 tests was designed to explore the effect of calcium chloride vs. sodium chloride and the ratio R of nitrate concentration over chloride concentration on the repassivation potential of Alloy 22. Tests were conducted using the cyclic potentiodynamic polarization (CPP) technique at 75 C and at 90 C. Results show that at a ratio R of 0.18 and higher nitrate was able to inhibit the crevice corrosion in Alloy 22 induced by chloride. Current results fail to show in a consi… more
Date: August 13, 2007
Creator: Tully, L. K.; White, A. D.; Goerz, D. A.; Javedani, J. B. & Houck, T. L.
Partner: UNT Libraries Government Documents Department
open access

REMOTELY RECHARGEABLE EPD

Description: Radiation measurements inside the Contact Decon Maintenance Cell (CDMC) in the Defense Waste Processing Facility (DWPF) at the Savannah River Site (SRS) are required to determine stay times for personnel. A system to remotely recharge the transmitter of an Electronic Personnel Dosimeter (EPD) and bail assembly to transport the EPD within the CDMC was developed by the Savannah River National Laboratory (SRNL) to address this need.
Date: November 13, 2007
Creator: Vrettos, N; Athneal Marzolf, A & Scott Bowser, S
Partner: UNT Libraries Government Documents Department
open access

Flavorful supersymmetry

Description: Weak scale supersymmetry provides elegant solutions to many of the problems of the standard model, but it also generically gives rise to excessive flavor and CP violation. We show that, if the mechanism that suppresses the Yukawa couplings also suppresses flavor changing interactions in the supersymmetry breaking parameters, essentially all the low energy flavor and CP constraints can be satisfied. The standard assumption of flavor universality in the supersymmetry breaking sector is not necess… more
Date: December 13, 2007
Creator: Nomura, Yasunori; Nomura, Yasunori; Papucci, Michele & Stolarski, Daniel
Partner: UNT Libraries Government Documents Department
open access

Language Classification using N-grams Accelerated by FPGA-based Bloom Filters

Description: N-Gram (n-character sequences in text documents) counting is a well-established technique used in classifying the language of text in a document. In this paper, n-gram processing is accelerated through the use of reconfigurable hardware on the XtremeData XD1000 system. Our design employs parallelism at multiple levels, with parallel Bloom Filters accessing on-chip RAM, parallel language classifiers, and parallel document processing. In contrast to another hardware implementation (HAIL algorithm… more
Date: September 13, 2007
Creator: Jacob, A. & Gokhale, M.
Partner: UNT Libraries Government Documents Department
open access

USSP-IAEA Workshop on Advanced Sensors for Safeguards

Description: The IAEA Medium Term Strategy (2006-2011) defines a number of specific goals in respect to the IAEA's ability to provide assurances to the international community regarding the peaceful use of nuclear energy through States adherences to their respective non-proliferation treaty commitments. The IAEA has long used and still needs the best possible sensors to detect and measure nuclear material. The Department of Safeguards, recognizing the importance of safeguards-oriented R&D, especially ta… more
Date: November 13, 2007
Creator: Pepper,Susan; Queirolo, A.; Zendel, M.; Whichello, J.; Annese, C.; Griebe, J. et al.
Partner: UNT Libraries Government Documents Department
open access

A Study of Detonation Propagation and Diffraction with Compliant Confinement

Description: A previous computational study of diffracting detonations with the ignition-and-growth model demonstrated that contrary to experimental observations, the computed solution did not exhibit dead zones. For a rigidly confined explosive it was found that while diffraction past a sharp corner did lead to a temporary separation of the lead shock from the reaction zone, the detonation re-established itself in due course and no pockets of unreacted material were left behind. The present investigation c… more
Date: August 13, 2007
Creator: Banks, J; Schwendeman, D; Kapila, A & Henshaw, W
Partner: UNT Libraries Government Documents Department
open access

Unexpected Cancellations in Gravity Theories

Description: Recent computations of scattering amplitudes show that N = 8 supergravity is surprisingly well behaved in the ultraviolet and may even be ultraviolet finite in perturbation theory. The novel cancellations necessary for ultraviolet finiteness first appear at one loop in the guise of the ''no-triangle hypothesis''. We study one-loop amplitudes in pure Einstein gravity and point out the existence of cancellations similar to those found previously in N = 8 supergravity. These cancellations go beyon… more
Date: July 13, 2007
Creator: Bern, Z.; Carrasco, J.J.; /UCLA; Forde, D.; /SLAC, /UCLA; Ita, H. et al.
Partner: UNT Libraries Government Documents Department
open access

Event-by-Event Simulation of Induced Fission

Description: We are developing a novel code that treats induced fission by statistical (or Monte-Carlo) simulation of individual decay chains. After its initial excitation, the fissionable compound nucleus may either deexcite by evaporation or undergo binary fission into a large number of fission channels each with different energetics involving both energy dissipation and deformed scission prefragments. After separation and Coulomb acceleration, each fission fragment undergoes a succession of individual (n… more
Date: December 13, 2007
Creator: Vogt, R. & Randrup, J.
Partner: UNT Libraries Government Documents Department
Back to Top of Screen