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Preparation and Reactions of Base-FreeBis(1,2,4-tri-tert-butylcyclopentadienyl)uranium Oxide, Cp'2UO

Description: Reduction of the uranium metallocene,[eta5-1,2,4-(Me3C)3C5H2]2UCl2 (1), Cp'2UCl2, in the presence of2,2'-bipyridyl and sodium naphthalene gives the dark green metallocenecomplex, Cp'2U(bipy) (6), which reacts with p-tolylazide orpyridine-N-oxide to give Cp'2U=N(p-tolyl) (7) or Cp'2U(O)(py) (8),respectively. The Lewis acid, BPh3, precipitates Ph3B(py) and gives thebase-free oxo, Cp'2UO (10), which crystallizes from pentane. Theoxometallocene 10 behaves as a nucleophile with Me3SiX reagents but i… more
Date: May 25, 2005
Creator: Zi, Guofu; Werkema, Evan L.; Walter, Marc D.; Gottfriedsen,Jochen P. & Andersen, Richard A.
Partner: UNT Libraries Government Documents Department
open access

Estimating large-scale fracture permeability of unsaturatedrockusing barometric pressure data

Description: We present a three-dimensional modeling study of gas flow inthe unsaturated fractured rock of Yucca Mountain. Our objective is toestimate large-scale fracture permeability, using the changes insubsurface pneumatic pressure in response to barometric pressure changesat the land surface. We incorporate the field-measured pneumatic datainto a multiphase flow model for describing the coupled processes ofliquid and gas flow under ambient geothermal conditions. Comparison offield-measured pneumatic da… more
Date: May 17, 2005
Creator: Wu, Yu-Shu; Zhang, Keni & Liu, Hui-Hai
Partner: UNT Libraries Government Documents Department
open access

Effective Supergravity from the Weakly Coupled HeteroticString

Description: The motivation for Calabi-Yau-like compactifications of the weakly coupled E{sub 8} {circle_times} E{sub 8} heterotic string theory, its particle spectrum and the issue of dilaton stabilization are briefly reviewed. Modular invariant models for hidden sector condensation and supersymmetry breaking are described at the quantum level of the effective field theory. Their phenomenological and cosmological implications, including a possible origin for R-parity, are discussed.
Date: May 1, 2005
Creator: Gaillard, Mary K.
Partner: UNT Libraries Government Documents Department
open access

New developments for the site-specific attachment of protein to surfaces

Description: Protein immobilization on surfaces is of great importance in numerous applications in biology and biophysics. The key for the success of all these applications relies on the immobilization technique employed to attach the protein to the corresponding surface. Protein immobilization can be based on covalent or noncovalent interaction of the molecule with the surface. Noncovalent interactions include hydrophobic interactions, hydrogen bonding, van der Waals forces, electrostatic forces, or physic… more
Date: May 12, 2005
Creator: Camarero, J A
Partner: UNT Libraries Government Documents Department
open access

Experimental Determination of Apery-Like Identities forZeta(2n+2)

Description: We document the discovery of two generating functions forzeta(2n+2), analogous to earlier work for zeta(2n+1) and zeta(4n+3),initiated by Koecher and pursued further by Borwein, Bradley andothers.
Date: May 11, 2005
Creator: Bailey, David H.; Borwein, Jonathan M. & Bradley, David M.
Partner: UNT Libraries Government Documents Department
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Laser Guiding at Relativistic Intensities and Wakefield ParticleAcceleration in Plasma Channels

Description: High quality electron beams with hundreds of picoCoulombs ofcharge inpercent energy spread above 80 MeV were produced for the firsttime in high gradient laser wakefield accelerators by guiding the drivelaser pulse.
Date: May 1, 2005
Creator: Geddes, C. G. R.; Toth, Cs.; van Tilborg, J.; Esarey, E.; Schroeder, C. B.; Bruhwiler, D. et al.
Partner: UNT Libraries Government Documents Department
open access

3D-Simulation Studies of SNS Ring Doublet Magnets

Description: The accumulator ring of the Spallation Neutron Source (SNS) at ORNL employs in its straight sections closely packed quadrupole doublemagnets with large aperture of R=15.1 cm an relatively short iron-to-iron distance of 51.4 cm. These quads have much extended fringe field, and magnetic interferences among them in the doublet assemblies is not avoidable. Though each magnet in the assemblies has been individually mapped to high accuracy of lower than 0.01 percent level, the experimental data inclu… more
Date: May 5, 2005
Creator: Wang, J. G.; N., Tsoupas & Venturini, M.
Partner: UNT Libraries Government Documents Department
open access

Macro-System Model (Poster)

Description: Poster presentation on Macro-System Model for the 2005 Hydrogen, Fuel Cells & Infrastructure Technologies Program Annual Review held in Arlington, Virginia on May 23-26, 2005
Date: May 1, 2005
Creator: Ruth, M.
Partner: UNT Libraries Government Documents Department
open access

Study of the $\tau^- to 3h^- 2h^+ \nu_\tau$ Decay

Description: The branching fraction of the {tau}{sup -} {yields} 3h{sup -} 2h{sup +} {nu}{sub {tau}} decay (h = {pi}, K) is measured with the BABAR detector to be (8.56 {+-} 0.05 {+-} 0.42) x 10{sup -4}, where the first error is statistical and the second systematic. The observed structure of this decay is significantly different from the phase space prediction, with the {rho} resonance playing a strong role. The decay {tau}{sup -} {yields} f{sub 1}(1285){pi}{sup -}{nu}{sub {tau}}, with the f{sub 1}(1285) m… more
Date: May 4, 2005
Creator: Aubert, Bernard; Barate, R.; Boutigny, D.; Couderc, F.; Karyotakis, Y.; Lees, J. P. et al.
Partner: UNT Libraries Government Documents Department
open access

Investigation of Microwave Instability on Electron Storage Ring TLS

Description: With the planned installation of a superconducting rf system, the new operation mode of TLS, the electron storage ring at NSRRC, is expected to double the beam intensity. Several accelerator physics topics need to be examined. Beam instability of single-bunch longitudinal microwave instability is one of these topics. We consider two approaches to measure the effective broad band impedance. We compare these measurement results with each other and to old data [Ref.1]. We calculate the threshold c… more
Date: May 17, 2005
Creator: Wang, M.-H. & Chao, A.
Partner: UNT Libraries Government Documents Department
open access

Preparation and Reactions of Base-FreeBis(1,2,4-tri-tert-butylcyclopentadienyl)uranium Methylimide, Cp'2U=NMe,and Related Compounds

Description: The uranium metallocenes, [eta5-1,3-(Me3E)2C5H3]2UMe2 (E =C, Si), react with NH3 to give the dimers{[eta5-1,3-(Me3E)2C5H3]2U}2(mu-NH)2 (E = C (1), Si (2)) but withp-toluidine to give the monomeric diamides,[eta5-1,3-(Me3E)2C5H3]2U(NH-p-tolyl)2 (E = C (3), Si (4)). The diamides[eta5-1,3-(Me3E)2C5H3]2U(NH-p-tolyl)2 (E = C (3), Si (4)) do noteliminate p- toluidine but sublime intact at 140oC in vacuum. The uraniummetallocene, [eta5-1,2,4-(Me3C)3C5H2]2UMe2, reacts with RNH2 to yield[eta5-1,2,4-(Me3… more
Date: May 27, 2005
Creator: Zi, Guofu; Blosch, Laura L.; Jia, Li & Andersen, Richard A.
Partner: UNT Libraries Government Documents Department
open access

Verification of high-order mixed FEM solution of transient Magnetic diffusion problems

Description: We develop and present high order mixed finite element discretizations of the time dependent electromagnetic diffusion equations for solving eddy current problems on 3D unstructured grids. The discretizations are based on high order H(grad), H(curl) and H(div) conforming finite element spaces combined with an implicit and unconditionally stable generalized Crank-Nicholson time differencing method. We develop three separate electromagnetic diffusion formulations, namely the E (electric field), H… more
Date: May 12, 2005
Creator: Rieben, R. & White, D. A.
Partner: UNT Libraries Government Documents Department
open access

How an antenna launches its input power into radiation: thepattern of the Poynting vector at and near an antenna

Description: In this paper I first address the question of whether theseat of the power radiated by an antenna made of conducting members isdistributed over the "arms" of the antenna according to $ - \bf J \cdotE$, where $\bf J$ is the specified current density and $\bf E$ is theelectric field produced by that source. Poynting's theorem permits only aglobal identification of the total input power, usually from a localizedgenerator, with the total power radiated to infinity, not a localcorrespondence of $- \… more
Date: May 18, 2005
Creator: Jackson, J.D.
Partner: UNT Libraries Government Documents Department
open access

EXTRACTION COMPRESSION AND ACCELERATION OF HIGH LINE CHARGE DENSITY ION BEAMS

Description: High Energy Density Physics (HEDP) applications require high line charge density ion beams. An efficient method to obtain this type of beams is to extract a long pulse, high current beam from a gun at high energy, and let the beam pass through a decelerating field to compress it. The low energy beam-bunch is loaded into a solenoid and matched to a Brillouin flow. The Brillouin equilibrium is independent of the energy if the relationship between the beam size (a), solenoid magnetic field strengt… more
Date: May 20, 2005
Creator: Henestroza, Enrique; Henestroza, E.; Peters, C.; Yu, S. S.; Grote, D. P. & Briggs, R. J.
Partner: UNT Libraries Government Documents Department
open access

Scale dependence of the effective matrix diffusion coefficient:some analytical results

Description: Matrix diffusion is an important process affecting solutetransport in fractured rock, and the matrix diffusion coefficient is akey parameter for describing this process. Previous studies haveindicated that the effective matrix-diffusion coefficient values,obtained from a number of field tracer tests, are enhanced in comparisonwith local values and may increase with test scale. In thiscommunication, we develop analytical expressions for the effective matrixdiffusion coefficient for two simple fr… more
Date: May 30, 2005
Creator: Liu, H. H.; Zhang, Y. Q. & Molz, F. J.
Partner: UNT Libraries Government Documents Department
open access

LIMITS OF Nb3Sn ACCELERATOR MAGNETS

Description: Pushing accelerator magnets beyond 10 T holds a promise of future upgrades to machines like the Tevatron at Fermilab and the LHC at CERN. Exceeding the current density limits of NbTi superconductor, Nb{sub 3}Sn is at present the only practical superconductor capable of generating fields beyond 10 T. Several Nb{sub 3}Sn pilot magnets, with fields as high as 16 T, have been built and tested, paving the way for future attempts at fields approaching 20 T. High current density conductor is required … more
Date: May 1, 2005
Creator: Caspi, Shlomo & Ferracin, Paolo
Partner: UNT Libraries Government Documents Department
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Beam Measurements and Upgrade at BL 7.2, the Second DiagnosticsBeamline of the Advanced Light Source

Description: Beamline 7.2 of the Advanced Light Source (ALS) at theLawrence Berkeley National Laboratory (LBNL) is a beam diagnostics systemthat uses the synchrotron radiation emitted by a dipole magnet. Itconsists of two branches; in the first one the x-ray portion of theradiation is used in a pinhole camera system for measuring the transverseprofile of the beam. The second branch is equipped with an x-ray beamposition monitor (BPM) and with a multipurpose port where the visible andthe far-infrared part of… more
Date: May 12, 2005
Creator: Scarvie, Tom; Sannibale, Fernando; Biocca, Alan; Kelez, Nicholas; Martin, Michael C.; Nishimura, Toshiro et al.
Partner: UNT Libraries Government Documents Department
open access

Fitting the luminosity decay in the Tevatron

Description: This paper explores how to fit the decay of the luminosity in the Tevatron. The standard assumptions of a fixed-lifetime exponential decay are only appropriate for very short time intervals. A ''1/time'' functional form fits well, and is supported by analytical derivations. A more complex form, assuming a time-varying lifetime-like term, also produces good results. Changes in the luminosity can be factored into two phenomena: The luminosity burn-off rate, and the burn-off rate from non-luminosi… more
Date: May 1, 2005
Creator: McCrory, E.; Shiltsev, V.; Slaughter, A. J. & Xiao, A.
Partner: UNT Libraries Government Documents Department
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Using star tracks to determine the absolute pointing of the Fluorescence Detector telescopes of the Pierre Auger Observatory

Description: To accurately reconstruct a shower axis from the Fluorescence Detector data it is essential to establish with high precision the absolute pointing of the telescopes. To d that they calculate the absolute pointing of a telescope using sky background data acquired during regular data taking periods. The method is based on the knowledge of bright star's coordinates that provide a reliable and stable coordinate system. it can be used to check the absolute telescope's pointing and its long-term stab… more
Date: May 1, 2005
Creator: De Donato, Cinzia; Sanchez, Federico; /Milan U. /INFN, Milan; Santander, Marcos; Natl.Tech.U., San Rafael; Camin, Daniel et al.
Partner: UNT Libraries Government Documents Department
open access

Advances in the understanding and operations of superconducting colliders

Description: Chromaticity drift during injection is a well-known phenomenon in superconducting colliders, such as the Tevatron, HERA and RHIC. Imperfect compensation of the drift effects can contribute to beam loss and emittance growth. It is caused by the drift of the sextupole component in the dipole magnets due to current redistribution in its superconducting coils. Recently extensive studies of chromaticity drift were conducted at the Tevatron, aiming at the improvement of the luminosity performance in … more
Date: May 1, 2005
Creator: Annala, G.; Bauer, P.; Bottura, L.; Martens, M. A.; Sammut, N.; Velev, G. et al.
Partner: UNT Libraries Government Documents Department
open access

US accelerator contribution to the LHC

Description: In 1998, the United States entered into an agreement with CERN to help build the Large Hadron Collider (LHC), with contributions to the accelerator and to the large HEP detectors. To accomplish this, the US LHC Accelerator Project was formed, encompassing expertise from Brookhaven National Laboratory (BNL), Fermi National Accelerator Laboratory (FNAL) and the Lawrence Berkeley National Laboratory (LBNL). This report is a summary of these contributions including the progress towards project comp… more
Date: May 1, 2005
Creator: Lamm, Michael J.
Partner: UNT Libraries Government Documents Department
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