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GLAST and Suzaku: Study on Cosmic-Ray Acceleration And Interaction in the Cosmos

Description: The Gamma-Ray Large Area Space Telescope (GLAST) is an international and multiagency mission scheduled for launch in the fall 2007. The Large Area Telescope (LAT), the primary instrument of the mission, will survey the high energy sky found to be very dynamic and surprisingly diverse by its predecessor the Energetic Gamma Ray Experiment Telescope (EGRET). GLAST-LAT will have a much improved sensitivity when compared with EGRET and extend the higher energy coverage to {approx} 300 GeV. The instr… more
Date: May 23, 2008
Creator: Kamae, T. & /KIPAC, Menlo Park /SLAC
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

YT: A Multi-Code Analysis Toolkit for Astrophysical Simulation Data

Description: The analysis of complex multiphysics astrophysical simulations presents a unique and rapidly growing set of challenges: reproducibility, parallelization, and vast increases in data size and complexity chief among them. In order to meet these challenges, and in order to open up new avenues for collaboration between users of multiple simulation platforms, we present yt (available at http://yt.enzotools.org/) an open source, community-developed astrophysical analysis and visualization toolkit. Ana… more
Date: June 23, 2011
Creator: Turk, Matthew J.; /San Diego, CASS; Smith, Britton D.; U., /Michigan State; Oishi, Jeffrey S.; /KIPAC, Menlo Park /Stanford U., Phys. Dept. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Radiative B Decays

Description: I discuss recent results in radiative B decays from the Belle and BaBar collaborations. I report new measurements of the decay rate and CP asymmetries in b {yields} s{gamma} and b {yields} d{gamma} decays, and measurements of the photon spectrum in b {yields} s{gamma}. Radiative penguin decays are flavour changing neutral currents which do not occur at tree level in the standard model (SM), but must proceed via one loop or higher order diagrams. These transitions are therefore suppressed in the… more
Date: November 23, 2011
Creator: Bard, D.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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On the Importance of Symmetrizing RF Coupler Fields for Low Emittance Beams

Description: The input power of accelerator structure is normally fed through a coupling slot(s) on the outer wall of the accelerator structure via magnetic coupling. While providing perfect matching, the coupling slots may produce non-axial-symmetric fields in the coupler cell that can induce emittance growth as the beam is accelerated in such a field. This effect is especially important for low emittance beams at low energies such as in the injector accelerators for light sources. In this paper, we presen… more
Date: June 23, 2011
Creator: Li, Zenghai.; Zhou, Feng.; Vlieks, Arnold. & Adolphsen, Chris.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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ARPES Studies of Cuprate Fermiology: Superconductivity, Pseudogap and Quasiparticle Dynamics

Description: We present angle-resolved photoemission spectroscopy (ARPES) studies of the cuprate high-temperature superconductors which elucidate the relation between superconductivity and the pseudogap and highlight low-energy quasiparticle dynamics in the superconducting state. Our experiments suggest that the pseudogap and superconducting gap represent distinct states, which coexist below T{sub c}. Studies on Bi-2212 demonstrate that the near-nodal and near-antinodal regions behave differently as a funct… more
Date: June 23, 2011
Creator: Vishik, Inna
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Hidden magnetic configuration in epitaxial La1-rSrzMnO3 films

Description: We present an unreported magnetic configuration in epitaxial La{sub 1-x}Sr{sub x}MnO{sub 3} (x {approx} 0.3) (LSMO) films grown on strontium titanate (STO). X-ray magnetic circular dichroism indicates that the remanent magnetic state of thick LSMO films is opposite to the direction of applied magnetic field. Spectroscopic and scattering measurements reveal that the average Mn valence varies from mixed Mn{sup 3+}/Mn{sup 4+} to an enriched Mn{sup 3+} region near the STO interface, resulting in a … more
Date: May 23, 2011
Creator: Kao, Chi-Chang
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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The LCLS Timing Event System

Description: The Linac Coherent Light Source requires precision timing trigger signals for various accelerator diagnostics and controls at SLAC-NAL. A new timing system has been developed that meets these requirements. This system is based on COTS hardware with a mixture of custom-designed units. An added challenge has been the requirement that the LCLS Timing System must co-exist and 'know' about the existing SLC Timing System. This paper describes the architecture, construction and performance of the LCLS… more
Date: July 23, 2012
Creator: Dusatko, John; Allison, S.; Browne, M. & Krejcik, P.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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The LCLS Undulator Beam Loss Monitor Readout System

Description: The LCLS Undulator Beam Loss Monitor System is required to detect any loss radiation seen by the FEL undulators. The undulator segments consist of permanent magnets which are very sensitive to radiation damage. The operational goal is to keep demagnetization below 0.01% over the life of the LCLS. The BLM system is designed to help achieve this goal by detecting any loss radiation and indicating a fault condition if the radiation level exceeds a certain threshold. Upon reception of this fault si… more
Date: July 23, 2012
Creator: Dusatko, John; Browne, M.; Fisher, A. S.; Kotturi, D.; Norum, S. & Olsen, J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Gamma-Ray Pulsar Studies With GLAST

Description: Some pulsars have their maximum observable energy output in the gamma-ray band, offering the possibility of using these high-energy photons as probes of the particle acceleration and interaction processes in pulsar magnetospheres. After an extended hiatus between satellite missions, the recently-launched AGILE mission and the upcoming Gamma-ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT) will allow gamma-ray tests of the theoretical models developed based on past discoveries. … more
Date: November 23, 2011
Creator: Thompson, D. J. & /NASA, Goddard
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Can the Existence of Dark Energy be Directly Detected?

Description: The majority of astronomers and physicists accept the reality of dark energy and also believe that it can only be studied indirectly through observation of the motions of stars and galaxies. In this paper I open the experimental question of whether it is possible to directly detect dark energy through the presence of dark energy density. Two thirds of this paper outlines the major aspects of dark energy density as now comprehended by the astronomical and physics community. The final third summa… more
Date: November 23, 2011
Creator: Perl, Martin L. & /SLAC /KIPAC, Menlo Park
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Searches for Exotic X,Y, and Z- States with BaBar

Description: Recently, several charmonium-like states above D{bar D} threshold have been discovered at the BELLE and BABAR B-factories. Some of these states are produced via Initial State Radiation (e.g. Y (4260) and Y (4350)) and some are observed in B meson decays (e.g. X(3872), Y (3940)). The BELLE observation of the enhancement in the {psi}(2S){pi}{sup -}, i.e. the Z(4430){sup -} state, has generated a great deal of interest, because such a state must have minimum quark content (c{bar c}d{bar u}), so th… more
Date: November 23, 2011
Creator: Mokhtar, Arafat Gabareen
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Preliminary Analysis on Linac Oscillation Data LI05-19 and Wake Field Energy Loss in FACET Commissioning 2012

Description: In this note, preliminary analysis on linac ocsillation data in FACET linac LI05-09 plus LI11-19 is presented. Several quadrupoles are identified to possibly have different strength, compared with their designed strength in the MAD optics model. The beam energy loss due to longitudinal wake fields in the S-band linac is also analytically calculated, also by LITRACK numerical simulations.
Date: July 23, 2012
Creator: Sun, Yipeng
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Undulator Beam Pipe Magnetic Shielding Effect Tests

Description: The proposed stainless steel beampipe for the LCLS undulator has a measurable shielding effect on the magnetic field of the LCLS undulators. This note describes the tests used to determine the magnitude of the shielding effect, as well as deviations in the shielding effect caused by placing different phase shims in the undulator gap. The effect of the proposed Steel strongback which will be used to support the beam pipe, was also studied. A hall probe on a 3 axis movement system was set up to m… more
Date: November 23, 2010
Creator: Fisher, Andrew & Wolf, Zachary
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Generating Ultrashort Coherent Soft X-ray Radiation in Storage Rings Using Angular-modulated Electron Beams

Description: A technique is proposed to generate ultrashort coherent soft x-ray radiation in storage rings using angular-modulated electron beams. In the scheme a laser operating in the TEM01 mode is first used to modulate the angular distribution of the electron beam in an undulator. After passing through a special beam line with non-zero transfer matrix element R{sub 54}, the angular modulation is converted to density modulation which contains considerable higher harmonic contents of the laser. It is foun… more
Date: August 23, 2010
Creator: Xiang, D. & Wan, W.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Optimization of Dynamic Aperture of PEP-X Baseline Design

Description: SLAC is developing a long-range plan to transfer the evolving scientific programs at SSRL from the SPEAR3 light source to a much higher performing photon source. Storage ring design is one of the possibilities that would be housed in the 2.2-km PEP-II tunnel. The design goal of PEPX storage ring is to approach an optimal light source design with horizontal emittance less than 100 pm and vertical emittance of 8 pm to reach the diffraction limit of 1-{angstrom} x-ray. The low emittance design req… more
Date: August 23, 2010
Creator: Wang, Min-Huey; Cai, Yunhai & Nosochkov, Yuri
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Report on Modifications to the BX12 and BX13 BC1 Dipoles

Description: Emittance growth seen during the last commissioning run in the bunch compressor optics section, BC1, was blamed on inadequate dipole field quality. The significant linear and nonlinear field non-uniformities generated large horizontal dispersion errors beyond BC1. The linear dispersion after BC1 was corrected using two small 'corrector' quadrupoles placed in BC1 for this purpose, but the remaining nonlinear field caused growth of the normalized horizontal emittance of 40% or more. At best {gamm… more
Date: November 23, 2010
Creator: Welch, James; DeBarge, S.; Emma, P.; Fisher, A.; Li, N. & Wu, J.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Top Quark Amplitudes with an Anomolous Magnetic Moment

Description: The anomalous magnetic moment of the top quark may be measured during the first run of the LHC at 7 TeV. For these measurements, it will be useful to have available tree amplitudes with t{bar t} and arbitrarily many photons and gluons, including both QED and color anomalous magnetic moments. In this paper, we present a method for computing these amplitudes using the Britto-Cachazo-Feng-Witten recursion formula. Because we deal with an effective theory with higher-dimension couplings, there are … more
Date: June 23, 2011
Creator: Larkoski, Andrew J. & Peskin, Michael E.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Modified Magnetic Ground State in Nimn (2) O (4) Thin Films

Description: The authors demonstrate the stabilization of a magnetic ground state in epitaxial NiMn{sub 2}O{sub 4} (NMO) thin films not observed in their bulk counterpart. Bulk NMO exhibits a magnetic transition from a paramagnetic phase to a collinear ferrimagnetic moment configuration below 110 K and to a canted moment configuration below 70 K. By contrast, as-grown NMO films exhibit a single magnetic transition at 60 K and annealed films exhibit the magnetic behavior found in bulk. Cation inversion and e… more
Date: August 23, 2012
Creator: Nelson-Cheeseman, B. B.; Chopdekar, R. V.; Iwata, J. M.; Toney, M. F.; Arenholz, E. & Suzuki, Y.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Multipacting Analysis for the Half-Wave Spoke Resonator Crab Cavity for LHC

Description: A compact 400-MHz half-wave spoke resonator (HWSR) superconducting crab cavity is being developed for the LHC upgrade. The cavity shape and the LOM/HOM couplers for such a design have been optimized to meet the space and beam dynamics requirements, and satisfactory RF parameters have been obtained. As it is known that multipacting is an issue of concern in a superconducting cavity which may limit the achievable gradient. Thus it is important in the cavity RF design to eliminate the potential MP… more
Date: June 23, 2011
Creator: Ge, Lixin & Li, Zenghai
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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