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Strangeness at SIS energies

Description: In this contribution the authors discuss the physics of strange hadrons in low energy ({approx_equal} 1-2 AGeV) heavy ion collision. In this energy range the relevant strange particle are the kaons and anti-kaons. The most interesting aspect concerning these particles are so called in-medium modifications. They will attempt to review the current status of understanding of these in medium modifications. In addition they briefly discuss other issues related with kaon production, such as the nucle… more
Date: September 28, 2005
Creator: Koch, Volker
Partner: UNT Libraries Government Documents Department
open access

Sharp Reduction of the Secondary Electron Emission Yield from Grooved Surfaces

Description: The effect of an artificially-enhanced rough surface on the secondary electron emission yield (SEY) was investigated both theoretically and experimentally. Analytical studies on triangular and rectangular grooved surfaces show the connection between the characteristic parameters of a given geometry to the SEY reduction. The effect of a strong magnetic field is also discussed. SEY of grooved samples have been measured and the results agree with Monte-Carlo simulations.
Date: November 28, 2007
Creator: Pivi, M. T. F.; King, F. K.; Kirby, R. E.; Ruabenheimer, T. O.; Stupakov, G. & Le Pimpec, F.
Partner: UNT Libraries Government Documents Department
open access

OPTICAL AND DYNAMIC PROPERTIES OF UNDOPED AND DOPED SEMICONDUCTOR NANOSTRUCTURES

Description: This chapter provides an overview of some recent research activities on the study of optical and dynamic properties of semiconductor nanomaterials. The emphasis is on unique aspects of these properties in nanostructures as compared to bulk materials. Linear, including absorption and luminescence, and nonlinear optical as well as dynamic properties of semiconductor nanoparticles are discussed with focus on their dependence on particle size, shape, and surface characteristics. Both doped and undo… more
Date: September 28, 2007
Creator: Grant, C D & Zhang, J Z
Partner: UNT Libraries Government Documents Department
open access

A Markov-Chain Monte-Carlo Based Method for Flaw Detection in Beams

Description: A Bayesian inference methodology using a Markov Chain Monte Carlo (MCMC) sampling procedure is presented for estimating the parameters of computational structural models. This methodology combines prior information, measured data, and forward models to produce a posterior distribution for the system parameters of structural models that is most consistent with all available data. The MCMC procedure is based upon a Metropolis-Hastings algorithm that is shown to function effectively with noisy dat… more
Date: September 28, 2006
Creator: Glaser, R. E.; Lee, C. L.; Nitao, J. J.; Hickling, T. L. & Hanley, W. G.
Partner: UNT Libraries Government Documents Department
open access

Mapping the geometry of the F4 group

Description: In this paper, we present a construction of the compact form of the exceptional Lie group F4 by exponentiating the corresponding Lie algebra f4. We realize F4 as the automorphisms group of the exceptional Jordan algebra, whose elements are 3 x 3 Hermitian matrices with octonionic entries. We use a parametrization which generalizes the Euler angles for SU(2) and is based on the fibration of F4 via a Spin(9) subgroup as a fiber. This technique allows us to determine an explicit expression for the… more
Date: May 28, 2007
Creator: Bernardoni, Fabio; Cacciatori, Sergio L; Scotti, Antonio & Cerchiai, Bianca L.
Partner: UNT Libraries Government Documents Department
open access

Effect of Organic Acid Additions on the General and Localized Corrosion Susceptibility of Alloy 22 in Chloride Solutions

Description: Electrochemical studies such as cyclic potentiodynamic polarization (CPP) and electrochemical impedance spectroscopy (EIS) were performed to determine the corrosion behavior of Alloy 22 (N06022) in 1M NaCl solutions at various pH values from acidic to neutral at 90 C. All the tested material was wrought Mill Annealed (MA). Tests were also performed in NaCl solutions containing weak organic acids such as oxalic, acetic, citric and picric. Results show that the corrosion rate of Alloy 22 was sign… more
Date: August 28, 2007
Creator: Carranza, R M; Giordano, C M; Rodr?guez, M A; Ilevbare, G O & Rebak, R B
Partner: UNT Libraries Government Documents Department
open access

An Incompressible Navier-Stokes with Particles Algorithm andParallel Implementation

Description: We present a variation of an adaptive projection method forcomputing solutions to the incompressible Navier-Stokes equations withsuspended particles. To compute the divergence-free component of themomentum forcing due to the particle drag, we employ an approach whichexploits the locality and smoothness of the Laplacian of the projectionoperator applied to the discretized particle drag force. We presentconvergence and performance results to demonstrate the effectiveness ofthis approach.
Date: November 28, 2006
Creator: Martin, Daniel F.; Colella, Phillip & Keen, Noel D.
Partner: UNT Libraries Government Documents Department
open access

Appliances, Lighting, Electronics, and Miscellaneous EquipmentElectricity Use in New Homes

Description: The "Other" end-uses (appliances, lighting, electronics, andmiscellaneous equipment) continue to grow. This is particularly true innew homes, where increasing floor area and amenities are leading tohigher saturation of these types of devices. This paper combines thefindings of several field studies to assess the current state ofknowledge about the "Other" end-uses in new homes. The field studiesinclude sub-metered measurements of occupied houses in Arizona, Florida,and Colorado, as well as devi… more
Date: February 28, 2007
Creator: Brown, Richard E.; Rittelman, William; Parker, Danny & Homan,Gregory
Partner: UNT Libraries Government Documents Department
open access

HYDROGEN EFFECTS ON THE FRACTURE TOUGHNESS PROPERTIES OF FORGED STAINLESS STEELS

Description: The effect of hydrogen on the fracture toughness properties of Types 304L, 316L and 21-6-9 forged stainless steels was investigated. Fracture toughness samples were fabricated from forward-extruded forgings. Samples were uniformly saturated with hydrogen after exposure to hydrogen gas at 34 MPa or 69 and 623 K prior to testing. The fracture toughness properties were characterized by measuring the J-R behavior at ambient temperature in air. The results show that the hydrogen-charged steels have … more
Date: March 28, 2008
Creator: Morgan, M
Partner: UNT Libraries Government Documents Department
open access

Synthesis and Characterization of Bimodal Nanoporous Cu Foams: Working Towards Inertial Fusion Energy

Description: For the National Ignition Facility, at the Lawrence Livermore National Laboratory, nanoporous structures play a crucial role in the development of targets for high energy density experiments. Here we present a new bottom-up synthesis technique termed filter-casting for the creation of bimodal macro/nanoporous Cu structures. Homogeneous nanoporous monoliths can be synthesized using Cu nanoparticles and bimodal porosities can be achieved using sacrificial polystyrene spheres as a template. Contro… more
Date: September 28, 2007
Creator: Cervantes, O; Hayes, J R & Hamza, A
Partner: UNT Libraries Government Documents Department
open access

Low Mach Number Modeling of Type Ia Supernovae. II. EnergyEvolution

Description: The convective period leading up to a Type Ia supernova (SNIa) explosion is characterized by very low Mach number flows, requiringhydrodynamical methods well-suited to long-time integration. We continuethe development of the low Mach number equation set for stellar scaleflows by incorporating the effects of heat release due to externalsources. Low Mach number hydrodynamics equations with a time-dependentbackground state are derived, and a numerical method based on theapproximate projection form… more
Date: March 28, 2006
Creator: Almgren, Ann S.; Bell, John B.; Rendleman, Charles A. & Zingale,Mike
Partner: UNT Libraries Government Documents Department
open access

Dielectric Wakefield Accelerator Experiments at the SABER Facility

Description: Electron bunches with the unparalleled combination of high charge, low emittances, and short time duration, as first produced at the SLAC Final Focus Test Beam (FFTB), are foreseen to be produced at the SABER facility. These types of bunches have enabled wakefield driven accelerating schemes of multi-GV/m in plasmas. In the context of the Dielectric Wakefield Accelerators (DWA) such beams, having rms bunch length as short as 20 um, have been used to drive 100 um and 200 um ID hollow tubes above… more
Date: January 28, 2008
Creator: Kanareykin, A.; Thompson, M. C.; Berry, M. K.; Blumenfeld, I.; Decker, F. J.; Hogan, M. J. et al.
Partner: UNT Libraries Government Documents Department
open access

Development of Wind-and-React Bi-2212 Accelerator MagnetTechnology

Description: We report on the progress in our R&D program, targetedto develop the technology for the application of Bi2Sr2CaCu2Ox (Bi-2212)in accelerator magnets. The program uses subscale coils, wound frominsulated cables, to study suitable materials, heat treatmenthomogeneity, stability, and effects ofmagnetic field and thermal andelectro-magnetic loads. We have addressed material and reaction relatedissues and report onthe fabrication, heat treatment, and analysis ofsubscale Bi-2212 coils. Such coils can… more
Date: August 28, 2007
Creator: Godeke, A.; Cheng, D.; Dietderich, D. R.; English, C. D.; Felice, H.; Hannaford, C. R. et al.
Partner: UNT Libraries Government Documents Department
open access

Prediction of the bubble point pressure for the binary mixture of ethanol and 1,1,1,2,3,3,3-heptafluoropropane from Gibbs ensemble Monte Carlo simulations using the TraPPE force field

Description: Configurational-bias Monte Carlo simulations in the Gibbs ensemble using the TraPPE force field were carried out to predict the pressure-composition diagrams for the binary mixture of ethanol and 1,1,1,2,3,3,3-heptafluoropropane at 283.17 and 343.13 K. A new approach is introduced that allows to scale predictions at one temperature based on the differences in Gibbs free energies of transfer between experiment and simulation obtained at another temperature. A detailed analysis of the molecular s… more
Date: February 28, 2007
Creator: Rai, N; Rafferty, J L; Maiti, A & Siepmann, I
Partner: UNT Libraries Government Documents Department
open access

Restoration of Weak Phase-Contrast Images Recorded With a High Degree of Defocus: The "Twin Image" Problem Associated With CTF Correction

Description: Relatively large values of objective-lens defocus must normally be used to produce detectable levels of image contrast for unstained biological specimens, which are generally weak phase objects. As a result, a subsequent restoration operation must be used to correct for oscillations in the contrast transfer function (CTF) at higher resolution. Currently used methods of CTF-correction assume the ideal case in which Friedel mates in the scattered wave have contributed pairs of Fourier components … more
Date: March 28, 2008
Creator: Downing, Kenneth H. & Glaeser, Robert M.
Partner: UNT Libraries Government Documents Department
open access

Search for CPT and Lorentz Violation in B0-B0bar Oscillations with Dilepton Events

Description: We report results of a search for CPT and Lorentz violation in B{sup 0}-{bar B}{sup 0} oscillations using inclusive dilepton events from 232 million {Upsilon}(4S) {yields} B{bar B} decays recorded by the BABAR detector at the PEP-II B Factory at SLAC. We find 2.8{sigma} significance, compatible with no signal, for variations in the complex CPT violation parameter z at the Earth's sidereal frequency and extract values for the quantities {Delta}a{sub {mu}} in the general Lorentz-violating standar… more
Date: November 28, 2007
Creator: Collaboration, The BABAR & Aubert, B.
Partner: UNT Libraries Government Documents Department
open access

Optical Damage Threshold of Silicon for Ultrafast Infrared Pulses

Description: We present measurements of the optical damage threshold of crystalline silicon in air for ultrafast pulses in the near infrared. The wavelengths tested span a range from the telecommunications band at 1550 nm, extending to 2260 nm. We discuss the motivation for the measurements and give theoretical context. We then describe the experimental setup, diagnostics, and procedure. The results show a breakdown threshold of 0.2J/cm{sup 2} at 1550 nm and 1.06 ps FWHM pulse duration, and a weak dependenc… more
Date: November 28, 2007
Creator: Cowan, Benjamin M. & /Tech-X, Boulder /SLAC
Partner: UNT Libraries Government Documents Department
open access

Flat Field Anomalies in an X-ray CCD Camera Measured Using a Manson X-ray Source (HTPD 08 paper)

Description: The Static X-ray Imager (SXI) is a diagnostic used at the National Ignition Facility (NIF) to measure the position of the X-rays produced by lasers hitting a gold foil target. The intensity distribution taken by the SXI camera during a NIF shot is used to determine how accurately NIF can aim laser beams. This is critical to proper NIF operation. Imagers are located at the top and the bottom of the NIF target chamber. The CCD chip is an X-ray sensitive silicon sensor, with a large format array (… more
Date: April 28, 2008
Creator: Haugh, M & Schneider, M B
Partner: UNT Libraries Government Documents Department
open access

Highly Effective Polarized Electron Sources Based on Strained Semiconductor Superlattice with Distributed Bragg Reflector

Description: Resonance enhancement of the quantum efficiency of new polarized electron photocathodes based on a short-period strained superlattice structures is reported. The superlattice is a part of an integrated Fabry-Perot optical cavity. We demonstrate that the Fabry-Perot resonator enhances the quantum efficiency by the order of magnitude in the wavelength region of the main polarization maximum. The high structural quality implied by these results points to the very promising application of these pho… more
Date: November 28, 2007
Creator: Gerchikov, L. G.; Aulenbacher, K.; Clendenin, J. E.; Kuz'michev, V. V.; Mamaev, Yu. A.; Maruyama, T. et al.
Partner: UNT Libraries Government Documents Department
open access

Summary of Polarized e-/e+ Source Presentations

Description: The development of polarized electron sources in the 1970s capable of generating beams for injection into electron accelerators has been a major enabling factor for spin physics with electrons during the past quarter century. These sources continue to be refined for higher polarization and better operability. Recent developments were presented at this workshop in both plenary sessions and in 2 separate parallel sessions. The ILC plans to utilize not only a polarized electron source but also a p… more
Date: November 28, 2007
Creator: Clendenin, J. E.
Partner: UNT Libraries Government Documents Department
open access

Analysis of the structure of complex networks at different resolution levels

Description: Modular structure is ubiquitous in real-world complex networks, and its detection is important because it gives insights in the structure-functionality relationship. The standard approach is based on the optimization of a quality function, modularity, which is a relative quality measure for a partition of a network into modules. Recently some authors have pointed out that the optimization of modularity has a fundamental drawback: the existence of a resolution limit beyond which no modular struc… more
Date: February 28, 2008
Creator: Arenas, A.; Fernandez, A. & Gomez, S.
Partner: UNT Libraries Government Documents Department
open access

Improvements in Monte Carlo Simulation of Large Electron Fields

Description: Two Monte Carlo systems, EGSnrc and Geant4, were used to calculate dose distributions in large electron fields used in radiotherapy. Source and geometry parameters were adjusted to match calculated results with measurement. Both codes were capable of accurately reproducing the measured dose distributions of the 6 electron beams available on the accelerator. Depth penetration was matched to 0.1 cm. Depth dose curves generally agreed to 2% in the build-up region, although there is an additional 2… more
Date: November 28, 2007
Creator: Faddegon, Bruce A.; /UC, San Francisco; Perl, Joseph & Asai, Makoto
Partner: UNT Libraries Government Documents Department
open access

Three-body breakup in dissociative electron attachment to the water molecule

Description: We report the results of {\em ab initio} calculations on dissociative electron attachment (DEA) to water that demonstrate the importance of including three-body breakup in the dissociation dynamics. While three-body breakup is ubiquitous in the analogous process of dissociative recombination, its importance in low-energy dissociative electron attachment to a polyatomic target has not previously been quantified. Our calculations, along with our earlier studies of DEA into two-body channels, indi… more
Date: August 28, 2008
Creator: Haxton, Daniel J.; Rescigno, Thomas N. & McCurdy, C. William
Partner: UNT Libraries Government Documents Department
open access

Dissolved gas and isotopic tracers of denitrification

Description: We present results from field studies in California (USA) where tritium-helium age dating is used in conjunction with major gases (N{sub 2}, O{sub 2}, CH{sub 4}, CO{sub 2}), noble gases (He, Ne, Ar, Kr, Xe), and stable isotopes ({sup 15}N/{sup 14}N, {sup 18}O/{sup 16}O) in order to document nitrate loading and denitrification associated with confined animal agricultural operations and septic systems. Preliminary results show that in-field extraction of the full suite of dissolved gases will be … more
Date: February 28, 2008
Creator: Singleton, M. J.; Moran, J. E.; Esser, B. K.; McNab, W. W.; Carle, S. F. & Cey, B. D.
Partner: UNT Libraries Government Documents Department
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