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BETA-RAY SPECTROMETER WITH REDUCED SPHERICAL ABERRATION

Description: Modern {beta}-ray spectrometers are based upon the concept, first introduced by Svartholm and Siegbahn in 1946, of focusing in both the radial and vertical directions. The theory of axially symmetric devices has been carefully studied by a large number of workers, culminating in the analysis, in 1956, of Lee-Whiting and Taylor. These last authors calculate aberrations through the sixth order and show that by appropriate choice of the magnetic field a spectrometer can be designed with a relative… more
Date: February 4, 1963
Creator: Sessler, Andrew M.
Partner: UNT Libraries Government Documents Department
open access

Ferromagnetism in GaN: Gd: A density functional theory study

Description: First principle calculations of the electronic structure and magnetic interaction of GaN:Gd have been performed within the Generalized Gradient Approximation (GGA) of the density functional theory (DFT) with the on-site Coulomb energy U taken into account (also referred to as GGA+U). The ferromagnetic p-d coupling is found to be over two orders of magnitude larger than the s-d exchange coupling. The experimental colossal magnetic moments and room temperature ferromagnetism in GaN:Gd reported re… more
Date: February 4, 2008
Creator: Stevenson, Cynthia & Stevenson, Cynthia
Partner: UNT Libraries Government Documents Department
open access

Status of the Fast Focusing DIRC (fDIRC)

Description: We have built and successfully tested a novel particle identification detector concept, the Fast Focusing DIRC (fDIRC). The prototype's concept is based on the BaBar DIRC with several important improvements: (a) much faster pixelated photon detectors based on Burle MCP-PMTs and Hamamatsu MaPMTs, (b) a focusing mirror allowing a smaller photon detector, reducing the sensitivity to backgrounds in future applications, (c) electronics capable of measuring the single photon resolution to better than… more
Date: February 4, 2008
Creator: Benitez, J.; Leith, D. W. G. S.; Mazaheri, G.; Ratcliff, B. N.; Schwiening, J.; Vavra, J. et al.
Partner: UNT Libraries Government Documents Department
open access

Ultrafast high strain rate acoustic wave measurements at high static pressure in a diamond anvil cell

Description: We have used sub-picosecond laser pulses to launch ultra-high strain rate ({approx} 10{sup 9} s{sup -1}) nonlinear acoustic waves into a 4:1 methanol-ethanol pressure medium which has been precompressed in a standard diamond anvil cell. Using ultrafast interferometry, we have characterized acoustic wave propagation into the pressure medium at static compression up to 24 GPa. We find that the velocity is dependent on the incident laser fluence, demonstrating a nonlinear acoustic response which m… more
Date: February 4, 2008
Creator: Armstrong, M; Crowhurst, J; Reed, E & Zaug, J
Partner: UNT Libraries Government Documents Department
open access

AdS/CFT and Light-Front QCD

Description: The AdS/CFT correspondence between string theory in AdS space and conformal field theories in physical space-time leads to an analytic, semi-classical model for strongly-coupled QCD which has scale invariance and dimensional counting at short distances and color confinement at large distances. The AdS/CFT correspondence also provides insights into the inherently nonperturbative aspects of QCD such as the orbital and radial spectra of hadrons and the form of hadronic wavefunctions. In particular… more
Date: February 4, 2008
Creator: Brodsky, Stanley J. & de Teramond, Guy F.
Partner: UNT Libraries Government Documents Department
open access

Prototype performance of novel muon telescope detector at STAR

Description: Research on a large-area, cost-effective Muon Telescope Detector has been carried out for RHIC and for next generation detectors at future QCD Lab. We utilize state-of-the-art multi-gap resistive plate chambers with large modules and long readout strips in detector design [l]. The results from cosmic ray and beam test will be presented to address intrinsic timing and spatial resolution for a Long-MRF'C. The prototype performance of a novel muon telescope detector at STAR will be reported, inclu… more
Date: February 4, 2008
Creator: Ruan,L. & Ames, V.
Partner: UNT Libraries Government Documents Department
open access

Compact MEMS-based Adaptive Optics Optical Coherence Tomography for Clinical Use

Description: We describe a compact MEMS-based adaptive optics (AO) optical coherence tomography system with improved AO performance and ease of clinical use. A typical AO system consists of a Shack-Hartmann wavefront sensor and a deformable mirror that measures and corrects the ocular and system aberrations. Because of the limitation on the current deformable mirror technologies, the amount of real-time ocular-aberration compensation is restricted and small in the previous AO-OCT instruments. In this instru… more
Date: February 4, 2008
Creator: Chen, D.; Olivier, S.; Jones, S.; Zawadzki, R.; Evans, J.; Choi, S. et al.
Partner: UNT Libraries Government Documents Department
open access

Scaling Behavior of the First Arrival Time of a Random-Walking Magnetic Domain

Description: We report a universal scaling behavior of the first arrival time of a traveling magnetic domain wall into a finite space-time observation window of a magneto-optical microscope enabling direct visualization of a Barkhausen avalanche in real time. The first arrival time of the traveling magnetic domain wall exhibits a nontrivial fluctuation and its statistical distribution is described by universal power-law scaling with scaling exponents of 1.34 {+-} 0.07 for CoCr and CoCrPt films, despite thei… more
Date: February 4, 2008
Creator: Im, M. Y.; Lee, S. H.; Kim, D. H.; Fischer, P. & Shin, S. C.
Partner: UNT Libraries Government Documents Department
open access

Difference Imaging of Lensed Quasar Candidates in the SDSS Supernova Survey Region

Description: Difference imaging provides a new way to discover gravitationally lensed quasars because few non-lensed sources will show spatially extended, time variable flux. We test the method on lens candidates in the Sloan Digital Sky Survey (SDSS) Supernova Survey region from the SDSS Quasar Lens Search (SQLS) and their surrounding fields. Starting from 20768 sources, including 49 SDSS quasars and 36 candidate lenses/lensed images, we find that 21 sources including 15 SDSS QSOs and 7 candidate lenses/le… more
Date: February 4, 2008
Creator: Lacki, Brian C.; Kochanek, Christopher S.; Stanek, Krzysztof Z.; Inada, Naohisa & Oguri, Masamune
Partner: UNT Libraries Government Documents Department
open access

Evidence for Color Transparency and Direct Hadron Production at RHIC

Description: The QCD color transparency of higher-twist contributions to the inclusive hadroproduction cross section, where the trigger proton is produced directly in a short-distance subprocess, can explain several remarkable features of high-p{sub T} proton production in heavy ion collisions which have recently been observed at RHIC: (a) the anomalous increase of the p {yields} {pi} ratio with centrality (b): the more rapid power-law fall-off at fixed x{sub T} = 2p{sub T}/{radical}s of the charged particl… more
Date: February 4, 2008
Creator: Brodsky, S
Partner: UNT Libraries Government Documents Department
open access

Semileptonic B Decays in BaBar

Description: Recent results from BABAR on the determination of the CKM matrix elements |V{sub cb}| and |V{sub ub}| are presented.
Date: February 4, 2008
Creator: Sacco, R. & /Queen Mary, U. of London
Partner: UNT Libraries Government Documents Department
open access

INNOVATIVE TECHNIQUES AND TECHNOLOGY APPLICATION IN MANAGEMENT OF REMOTE HANDLED AND LARGE SIZED MIXED WASTE FORMS

Description: CH2M HILL Hanford Group, Inc. (CH2M HILL) plays a critical role in Hanford Site cleanup for the U. S. Department of Energy, Office of River Protection (ORP). CH2M HILL is responsible for the management of 177 tanks containing 53 million gallons of highly radioactive wastes generated from weapons production activities from 1943 through 1990. In that time, 149 single-shell tanks, ranging in capacity from 50,000 gallons to 500,000 gallons, and 28 double-shell tanks with a capacity of 1 million gal… more
Date: February 4, 2008
Creator: LT, BLACKFORD
Partner: UNT Libraries Government Documents Department
open access

Photoionization Dynamics in Pure Helium Droplets

Description: The photoionization and photoelectron spectroscopy of pure He droplets are investigated at photon energies between 24.6 eV (the ionization energy of He) and 28 eV. Time-of-flight mass spectra and photoelectron images were obtained at a series of molecular beam source temperatures and pressures to assess the effect of droplet size on the photoionization dynamics. At source temperatures below 16 K, the photoelectron images are dominated by fast electrons produced via direct ionization of He atoms… more
Date: February 4, 2007
Creator: Peterka, Darcy S.; Kim, Jeong Hyun; Wang, Chia C.; Poisson, Lionel & Neumark, Daniel M.
Partner: UNT Libraries Government Documents Department
open access

\Dz - \Dzb Mixing Analyses at \babar

Description: The authors summarize results of analyses of D meson mixing parameters performed by the BABAR collaboration.
Date: February 4, 2008
Creator: Andreassen, Rolf & Collaboration, for the BaBar
Partner: UNT Libraries Government Documents Department
open access

A Gravity Dual of Metastable Dynamical Supersymmetry Breaking

Description: Metastable, supersymmetry-breaking configurations can be created in flux geometries by placing antibranes in warped throats. Via gauge/gravity duality, such configurations should have an interpretation as supersymmetry-breaking states in the dual field theory. In this paper, we perturbatively determine the asymptotic supergravity solutions corresponding to D3-brane probes placed at the tip of the cascading warped deformed conifold geometry, which is dual to an SU(N+M) x SU(N) gauge theory. The … more
Date: February 4, 2008
Creator: DeWolfe, Oliver; U., /Colorado; Kachru, Shamit; Mulligan, Michael & /Stanford U., Phys. Dept. /SLAC
Partner: UNT Libraries Government Documents Department
open access

Direct Functionalization of Nitrogen Heterocycles via Rh-Catalyzed C-H Bond Activation

Description: Nitrogen heterocycles are present in many compounds of enormous practical importance, ranging from pharmaceutical agents and biological probes to electroactive materials. Direct funtionalization of nitrogen heterocycles through C-H bond activation constitutes a powerful means of regioselectively introducing a variety of substituents with diverse functional groups onto the heterocycle scaffold. Working together, our two groups have developed a family of Rh-catalyzed heterocycle alkylation and ar… more
Date: February 4, 2008
Creator: Lewis, Jared; Bergman, Robert & Ellman, Jonathan
Partner: UNT Libraries Government Documents Department
open access

Trace Anomaly and Dimension Two Gluon Condensate Above the Phase Transition

Description: The dimension two gluon condensate has been used previously within a simple phenomenological model to describe power corrections from available lattice data for the renormalized Polyakov loop and the heavy quark-antiquark free energy in the deconfined phase of QCD. The QCD trace anomaly of gluodynamics also shows unequivocal inverse temperature power corrections which may be encoded as dimension two gluon condensate. We analyze lattice data of the trace anomaly and compare with other determinat… more
Date: February 4, 2008
Creator: Megias,E.; Ruiz Arriola, E. & Salcedo, L.L.
Partner: UNT Libraries Government Documents Department
open access

Electromagnetic Pulses at Short-Pulse Laser Facilities

Description: Electromagnetic Pulse (EMP) is a known issue for short-pulse laser facilities, and will also be an issue for experiments using the advanced radiographic capability (ARC) at the National Ignition Facility (NIF). The ARC diagnostic uses four NIF beams that are compressed to picosecond durations for backlighting ignition capsules and other applications. Consequently, we are working to understand the EMP due to high-energy (MeV) electrons escaping from targets heated by short-pulse lasers. Our appr… more
Date: February 4, 2008
Creator: Brown, C G; Throop, A; Eder, D & Kimbrough, J
Partner: UNT Libraries Government Documents Department
open access

Large plasma pressure perturbations and radial convective transport in a tokamak

Description: Strongly localized plasma structures with large pressure inhomogeneities (such as plasma blobs in the scrape-off-layer (SOL)/shadow regions, pellet clouds, ELMs) observed in the tokamaks, stellarators and linear plasma devices. Experimental studies of these phenomena reveal striking similarities including more convective rather than diffusive radial plasma transport. We suggest that rather simple models can describe many essentials of blobs, ELMs, and pellet clouds dynamics. The main ingredient… more
Date: February 4, 2004
Creator: Krasheninnikov, S.; Ryutov, D. & Yu, G.
Partner: UNT Libraries Government Documents Department
open access

Methods for developing seismic and extreme wind-hazard models for evaluating critical structures and equipment at US Department of Energy facilities and commercial plutonium facilities in the United States

Description: Lawrence Livermore National Laboratory (LLNL) is developing seismic and wind hazard models for the US Department of Energy (DOE). The work is part of a three-phase effort to establish building design criteria developed with a uniform methodology for seismic and wind hazards at the various DOE sites throughout the United States. In Phase 1, LLNL gathered information on the sites and their critical facilities, including nuclear reactors, fuel-reprocessing plants, high-level waste storage and trea… more
Date: February 4, 1981
Creator: Coats, D. W.; Murray, R. C. & Bernreuter, D. L.
Partner: UNT Libraries Government Documents Department
open access

Radionuclide limits for vault disposal at the Savannah River Site

Description: The Savannah River Site is developing a facility called the E-Area Vaults which will serve as the new radioactive waste disposal facility beginning early in 1992. The facility will employ engineered below-grade concrete vaults for disposal and above-grade storage for certain long-lived mobile radionuclides. This report documents the determination of interim upper limits for radionuclide inventories and concentrations which should be allowed in the disposal structures. The work presented here wi… more
Date: February 4, 1992
Creator: Cook, J. R.
Partner: UNT Libraries Government Documents Department
open access

D0 data management

Description: The management of data in programs for the D0 detector at the FNAL Tevatron collider is described with particular emphasis on aspects relevant to event reconstruction and data analysis. 3 figs.
Date: February 4, 1991
Creator: Protopopescu, S.
Partner: UNT Libraries Government Documents Department
open access

Radionuclide Limits for Vault Disposal at the Savannah River Site

Description: The Savannah River Site is developing a facility called the E-Area Vaults which will serve as the new radioactive waste disposal facility beginning early in 1992. The facility will employ engineered below-grade concrete vaults for disposal and above-grade storage for certain long-lived mobile radionuclides. This report documents the determination of interim upper limits for radionuclide inventories and concentrations which should be allowed in the disposal structures. The work presented here wi… more
Date: February 4, 1992
Creator: Cook, J. R.
Partner: UNT Libraries Government Documents Department
open access

Status of an induction accelerator driven, high-power microwave generator at Livermore

Description: The authors are testing an enhanced version of the Choppertron, a high-power rf generator which shows great promise of achieving greater than 400 MW of output power at 11.4 GHz with stable phase and amplitude. This version of the Choppertron is driven by a 5-MeV, 1-kA induction accelerator beam. Modifications to the original Choppertron included aggressive suppression of high order modes in the two output structures, lengthening of the modulation section to match for higher beam energy, and imp… more
Date: February 4, 1993
Creator: Houck, T. L. & Westenskow, G. A.
Partner: UNT Libraries Government Documents Department
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