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Estimating Liquid Fluxes in Thermally Perturbed Fractured RockUsing Measured Temperature Profiles (open access)

Estimating Liquid Fluxes in Thermally Perturbed Fractured RockUsing Measured Temperature Profiles

None
Date: February 14, 2005
Creator: Birkholzer, Jens T.
System: The UNT Digital Library
Beam-Loading Compensation for Super B-Factories (open access)

Beam-Loading Compensation for Super B-Factories

Super B-factory designs under consideration expect to reach luminosities in the 10{sup 35}-10{sup 36} range. The dramatic luminosity increase relative to the existing B-factories is achieved, in part, by raising the beam currents stored in the electron and positron rings. For such machines to succeed it is necessary to consider in the RF system design not only the gap voltage and beam power, but also the beam loading effects. The main effects are the synchronous phase transients due to the uneven ring filling patterns and the longitudinal coupled-bunch instabilities driven by the fundamental impedance of the RF cavities. A systematic approach to predicting such effects and for optimizing the RF system design will be presented. Existing as well as promising new techniques for reducing the effects of heavy beam loading will be described and illustrated with examples from the PEP-II and the KEKB.
Date: December 14, 2005
Creator: Teytelman, D.
System: The UNT Digital Library
Nitrogen Doping and Thermal Stability in HfSiOxNy Studied by Photoemission and X-ray Absorption Spectroscopy (open access)

Nitrogen Doping and Thermal Stability in HfSiOxNy Studied by Photoemission and X-ray Absorption Spectroscopy

We have investigated nitrogen-doping effects into HfSiO{sub x} films on Si and their thermal stability using synchrotron-radiation photoemission and x-ray absorption spectroscopy. N 1s core-level photoemission and N K-edge absorption spectra have revealed that chemical-bonding states of N-Si{sub 3-x}O{sub x} and interstitial N{sub 2}-gas-like features are clearly observed in as-grown HfSiO{sub x}N{sub y} film and they decrease upon ultrahigh vacuum (UHV) annealing due to a thermal instability, which can be related to the device performance. Annealing-temperature dependence in Hf 4f and Si 2p photoemission spectra suggests that the Hf-silicidation temperature is effectively increased by nitrogen doping into the HfSiO{sub x} although the interfacial SiO{sub 2} layer is selectively reduced. No change in valence-band spectra upon UHV annealing suggests that crystallization of the HfSiO{sub x}N{sub y} films is also hindered by nitrogen doping into the HfSiO{sub x}.
Date: December 14, 2005
Creator: Toyoda, Satoshi; Okabayashi, Jun; Takahashi, Haruhiko; Oshima, Masaharu; U., /Tokyo; Lee, Dong-Ick et al.
System: The UNT Digital Library
SUSY Parameter Measurements with Fittino (open access)

SUSY Parameter Measurements with Fittino

This article presents the results of a realistic global fit of the Lagrangian parameters of the Minimal Supersymmetric Standard Model with no assumptions on the SUSY breaking mechanism using the fit program Fittino. The fit is performed using the precision of future mass measurements of superpartners at the LHC and mass and polarized topological cross-section measurements at the ILC. Higher order radiative corrections are accounted for wherever possible to date. Results are obtained for a modified SPS1a MSSM benchmark scenario (general MSSM without assumptions on the breaking mechanism) and for a specific mSUGRA scenario. Exploiting a simulated annealing algorithm, a stable result is obtained without any a priori assumptions on the fit parameters. Most of the Lagrangian parameters can be extracted at the percent level or better if theoretical uncertainties are neglected. Neither LHC nor ILC measurements alone will be sufficient to obtain a stable result.
Date: December 14, 2005
Creator: Bechtle, P.; Desch, K. & Wienemann, P.
System: The UNT Digital Library
The Role of the ILC in the Study of Cosmic Dark Matter (open access)

The Role of the ILC in the Study of Cosmic Dark Matter

Though there is strong evidence that dark matter is a major component of the universe, most aspects of dark matter are completely mysterious. We do not know what dark matter is, and we do not know how it is distributed in our galaxy. To resolve these and related questions, we will need information both from particle physics and from astrophysics. In this article, we will describe a path toward the solution of the problems of dark matter, and we will highlight the important role that the ILC has to play in this study.
Date: December 14, 2005
Creator: Battaglia, Marco; /LBL, Berkeley /UC, Berkeley & Peskin, Michael E.
System: The UNT Digital Library
Distinguishing Seven Species of Bacillus Spores Using BioAerosol Mass Spectrometry (open access)

Distinguishing Seven Species of Bacillus Spores Using BioAerosol Mass Spectrometry

None
Date: October 14, 2005
Creator: Fergenson, D P; Pitesky, M E; Frank, M; Horn, J M & Gard, E E
System: The UNT Digital Library
Mechanical analysis of the Nb3Sn dipole magnet HD1 (open access)

Mechanical analysis of the Nb3Sn dipole magnet HD1

The Superconducting Magnet Group at Lawrence Berkeley National Laboratory (LBNL) has recently fabricated and tested HD1, a Nb{sub 3}Sn dipole magnet. The magnet reached a 16 T field, and exhibited training quenches in the end regions and in the straight section. After the test, HD1 was disassembled and inspected, and a detailed 3D finite element mechanical analysis was done to investigate for possible quench triggers. The study led to minor modifications to mechanical structure and assembly procedure, which were verified in a second test (HD1b). This paper presents the results of the mechanical analysis, including strain gauge measurements and coil visual inspection. The adjustments implemented in the magnet structure are reported and their effect on magnet training discussed.
Date: April 14, 2005
Creator: Ferracin, Paolo; Bartlett, Scott E.; Caspi, Shlomo; Dietderich,Daniel R.; Gourlay, Steve A.; Hannaford, Carles R. et al.
System: The UNT Digital Library
Revised Pulsar Spindown (open access)

Revised Pulsar Spindown

We address the issue of electromagnetic pulsar spindown by combining our experience from the two limiting idealized cases which have been studied in great extent in the past: that of an aligned rotator where ideal MHD conditions apply, and that of a misaligned rotator in vacuum. We construct a spindown formula that takes into account the misalignment of the magnetic and rotation axes, and the magnetospheric particle acceleration gaps. We show that near the death line aligned rotators spin down much slower than orthogonal ones. In order to test this approach, we use a simple Monte Carlo method to simulate the evolution of pulsars and find a good fit to the observed pulsar distribution in the P-{dot P} diagram without invoking magnetic field decay. Our model may also account for individual pulsars spinning down with braking index n < 3, by allowing the corotating part of the magnetosphere to end inside the light cylinder. We discuss the role of magnetic reconnection in determining the pulsar braking index. We show, however, that n {approx} 3 remains a good approximation for the pulsar population as a whole. Moreover, we predict that pulsars near the death line have braking index values n > …
Date: December 14, 2005
Creator: Contopoulos, Ioannis; Academy, /Athens; Spitkovsky, Anatoly & /KIPAC, Menlo Park
System: The UNT Digital Library
CLASSIC MANY BODY POTENTIAL FOR CONCENTRATED ALLOYS, AND THE INVERSION OF ORDER IN FE-CR (open access)

CLASSIC MANY BODY POTENTIAL FOR CONCENTRATED ALLOYS, AND THE INVERSION OF ORDER IN FE-CR

Atomistic simulations of alloys at the classic--or empirical--level face the challenge to correctly model basic thermodynamic properties. In this work we propose a methodology to generalize many-body classic potentials to incorporate complex formation energy curves. Application to Fe-Cr allows us to correctly predict the order vs segregation tendency in this alloy, as observed experimentally and calculated with ab initio techniques, providing in this way a potential suitable for radiation damage studies.
Date: April 14, 2005
Creator: Caro, A; Crowson, D A & Caro, M
System: The UNT Digital Library
Observation of Femtosecond Bunch Length Using a Transverse Deflecting Structure (open access)

Observation of Femtosecond Bunch Length Using a Transverse Deflecting Structure

The design of the VUV-FEL at DESY demands bunch lengths in the order of 50 fs and below. For the diagnostic of such very short bunches a transverse deflecting RF structure (LOLA) has been installed which streaks the beam according to the longitudinal distribution. Tests in the VUV-FEL yielded a rich substructure of the bunches. The most pronounced peak in the has a rms length of approximately 50 fs during FEL operation and below 20 fs FWHM at maximum compression. Depending on the transverse focusing a resolution well below 50 fs was achieved.
Date: December 14, 2005
Creator: Huning, Markus; Bolzmann, Andy; Schlarb, Holger; Frisch, Josef; McCormick, Douglas; Ross, Marc et al.
System: The UNT Digital Library
Radiation Spectrum Statistics in a High-Gain Free-Electron Laser at 266 nm (open access)

Radiation Spectrum Statistics in a High-Gain Free-Electron Laser at 266 nm

High Gain Harmonic Generation FEL is in operations at the DUV-FEL facility (BNL). During HGHG FEL characterization we have measured a set of data demonstrating basic properties of the FEL radiation and compared them with analytic calculations [1]. This paper describes continuation of characterization of the HGHG FEL radiation output, based on the spectral measurements. We discuss analysis of an experiment at which the tunability concept of a seeded FEL with a fixed seed wavelength has been verified [2]. During the experiment we recorded about 200 radiation spectra corresponding to different energy chirps in the electron beam. We have analyzed this set of spectral data to obtain statistical properties of HGHG radiation. Correlations and trends in the radiation spectrum at 266 nm have been observed and studied.
Date: December 14, 2005
Creator: Shaftan, T.; Sheehy, B.; Yu, L. H.; Murphy, J. B.; Krinsky, S.; Rose, J. et al.
System: The UNT Digital Library
Misconceptions about an Expanding Universe (open access)

Misconceptions about an Expanding Universe

Various results are obtained for a Friedmann-Robertson-Walker cosmology. We derive an exact equation that determines Hubble's law, clarify issues concerning the speeds of faraway objects and uncover a ''tail-light angle effect'' for distant luminous sources. The latter leads to a small, previously unnoticed correction to the parallax distance formula.
Date: December 14, 2005
Creator: Samuel, Stuart & /SLAC /LBL, Berkeley
System: The UNT Digital Library
Galactic Bulge Microlensing Events from the MACHO Collaboration (open access)

Galactic Bulge Microlensing Events from the MACHO Collaboration

None
Date: July 14, 2005
Creator: Thomas, C. L.; Griest, K.; Popowski, P.; Cook, K. H.; Drake, A. J.; Minniti, D. et al.
System: The UNT Digital Library
EXO: a Status Report (open access)

EXO: a Status Report

None
Date: December 14, 2005
Creator: Wamba, Kolo
System: The UNT Digital Library
Is the Universal String Axion the QCD Axion (open access)

Is the Universal String Axion the QCD Axion

We consider the class of effective supergravity theories from the weakly coupled heterotic string in which local supersymmetry is broken by gaugino condensation in a hidden sector, with dilaton stabilization achieved through corrections to the classical dilaton Kahler potential. If there is a single hidden condensing (simple) gauge group, the axion is massless (up to contributions from higher dimension operators) above the QCD condensation scale. We show how the standard relation between the axion mass and its Planck scale coupling constant is modified in this class of models due to a contribution to the axion-gluon coupling that appears below the scale of supersymmetry breaking when gluinos are integrated out. In particular there is a point of enhanced symmetry in parameter space where the axion mass is suppressed. We revisit the question of the universal axion as the Peccei-Quinn axion in the light of these results, and find that the strong CP problem is avoided in most compactifications of the weakly coupled heterotic string.
Date: October 14, 2005
Creator: Gaillard, Mary K. & Kain, Ben
System: The UNT Digital Library
Light-cone Sum Rules: A SCET-based Formulation (open access)

Light-cone Sum Rules: A SCET-based Formulation

We describe the construction of light-cone sum rules (LCSRs) for exclusive B-meson decays into light energetic hadrons from correlation functions within soft-collinear effective theory (SCET). As an example, we consider the SCET sum rule for the B {yields} {pi} transition form factor at large recoil, including radiative corrections from hard-collinear loop diagrams at first order in the strong coupling constant.
Date: December 14, 2005
Creator: De Fazio, F.; /INFN, Bari; Feldmann, Th.; U., /Siegen; Hurth, T. & /SLAC, /CERN
System: The UNT Digital Library
CKM Parameters and Rare B Decays (open access)

CKM Parameters and Rare B Decays

Measurements of the angles and sides of the unitarity triangle and of the rates of rare B meson decays are crucial for the precise determination of Standard Model parameters and are sensitive to the presence of new physics particles in the loop diagrams. In this paper the recent measurements performed in this area by BABAR and Belle will be presented. The direct measurement of the angle {alpha} is for the first time as precise as the indirect determination. The precision of the |V{sub ub}| determination has improved significantly with respect to previous measurement. New limits on B {yields} {tau}{nu} decays are presented, as well as updated measurements on b {yields} s radiative transitions and a new observation of b {yields} d{gamma} transition made by Belle.
Date: December 14, 2005
Creator: Forti, Francesco
System: The UNT Digital Library
Summary of Working Group 3a: Low Emittance Sources (open access)

Summary of Working Group 3a: Low Emittance Sources

We summarize the main issues and conclusions of the working group devoted to low emittance sources.
Date: December 14, 2005
Creator: Clendenin, J.; Lewellen, J. W.; Masuda, K. & Stephan, F.
System: The UNT Digital Library
The Supernova Legacy Survey: Measurement of Omega_M, Omega_Lambda,and w from the First Year Data Set (open access)

The Supernova Legacy Survey: Measurement of Omega_M, Omega_Lambda,and w from the First Year Data Set

We present distance measurements to 71 high redshift type Ia supernovae discovered during the first year of the 5-year Supernova Legacy Survey (SNLS). These events were detected and their multi-color light-curves measured using the MegaPrime/MegaCam instrument at the Canada-France-Hawaii Telescope (CFHT), by repeatedly imaging four one-square degree fields in four bands. Follow-up spectroscopy was performed at the VLT, Gemini and Keck telescopes to confirm the nature of the supernovae and to measure their redshift. With this data set, we have built a Hubble diagram extending to z = 1, with all distance measurements involving at least two bands. Systematic uncertainties are evaluated making use of the multiband photometry obtained at CFHT. Cosmological fits to this first year SNLS Hubble diagram give the following results: {Omega}{sub M} = 0.263 {+-} 0.042 (stat) {+-} 0.032 (sys) for a flat {Lambda}CDM model; and w = -1.023 {+-} 0.090 (stat) {+-} 0.054 (sys) for a flat cosmology with constant equation of state w when combined with the constraint from the recent Sloan Digital Sky Survey measurement of baryon acoustic oscillations.
Date: October 14, 2005
Creator: Astier, P.; Guy, J.; Regnault, N.; Pain, R.; Aubourg, E.; Balam, D. et al.
System: The UNT Digital Library
Measurements of sin2beta at BaBar with Charmonium and Penguin Decays (open access)

Measurements of sin2beta at BaBar with Charmonium and Penguin Decays

This article summarizes measurements of time-dependent CP asymmetries in decays of neutral B mesons to charmonium, open-charm and gluonic penguin-dominated charmless final states. Unless otherwise stated, these measurements are based on a sample of approximately 230 million {Upsilon}(4S) {yields} B{bar B} decays collected by the BABAR detector at the PEP-II asymmetric-energy B-factory.
Date: December 14, 2005
Creator: George, Katherine A.
System: The UNT Digital Library
A Twin Higgs Model from Left-Right Symmetry (open access)

A Twin Higgs Model from Left-Right Symmetry

We present twin Higgs models based on the extension of the Standard Model to left-right symmetry that protect the weak scale against radiative corrections up to scales of order 5 TeV. In the ultraviolet the Higgs sector of these theories respects an approximate global symmetry, in addition to the discrete parity symmetry characteristic of left-right symmetric models. The Standard Model Higgs field emerges as the pseudo-Goldstone boson associated with the breaking of the global symmetry. The parity symmetry tightly constrains the form of radiative corrections to the Higgs potential, allowing natural electroweak breaking. The minimal model predicts a rich spectrum of exotic particles that will be accessible to upcoming experiments, and which are necessary for the cancellation of one-loop quadratic divergences. These include right-handed gauge bosons with masses not to exceed a few TeV and a pair of vector-like quarks with masses of order several hundred GeV.
Date: December 14, 2005
Creator: Chacko, Z.; Goh, Hock-Seng; U., /Arizona; Harnik, Roni & /SLAC /Stanford U., Phys. Dept.
System: The UNT Digital Library
Role of Brownian Motion Hydrodynamics on Nanofluid Thermal Conductivity (open access)

Role of Brownian Motion Hydrodynamics on Nanofluid Thermal Conductivity

We use a simple kinetic theory based analysis of heat flow in fluid suspensions of solid nanoparticles (nanofluids) to demonstrate that the hydrodynamics effects associated with Brownian motion have a minor effect on the thermal conductivity of the nanofluid. Our conjecture is supported by the results of molecular dynamics simulations of heat flow in a model nanofluid with well-dispersed particles. Our findings are consistent with the predictions of the effective medium theory as well as with recent experimental results on well dispersed metal nanoparticle suspensions.
Date: November 14, 2005
Creator: W Evans, J Fish, P Keblinski
System: The UNT Digital Library
Using Nonlinear RF Acceleration for FEL Beam Conditioning (open access)

Using Nonlinear RF Acceleration for FEL Beam Conditioning

We consider a new approach to condition an electron beam using nonlinear effects in the RF field. We demonstrate that such effects can generate a desirable--for the FEL interaction--radial variation of the particle's energy in the beam, and calculate the induced energy spread in the limit of weak field.
Date: December 14, 2005
Creator: Stupakov, G. & Huang, Z.
System: The UNT Digital Library
Novel Aspects of Hard Diffraction in QCD (open access)

Novel Aspects of Hard Diffraction in QCD

Initial- and final-state interactions from gluon-exchange, normally neglected in the parton model have a profound effect in QCD hard-scattering reactions, leading to leading-twist single-spin asymmetries, diffractive deep inelastic scattering, diffractive hard hadronic reactions, and nuclear shadowing and antishadowing--leading-twist physics not incorporated in the light-front wavefunctions of the target computed in isolation. I also discuss the use of diffraction to materialize the Fock states of a hadronic projectile and test QCD color transparency.
Date: December 14, 2005
Creator: Brodsky, Stanley J.
System: The UNT Digital Library