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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.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Accelerator and Ion Beam Tradeoffs for Studies of Warm Dense Matter

Description: One approach for heating a target to ''Warm Dense Matter'' conditions (similar, for example, to the interiors of giant planets or certain stages in Inertial Confinement Fusion targets), is to use intense ion beams as the heating source (see refs.[6] and [7] and references therein for motivation and accelerator concepts). By consideration of ion beam phase space constraints, both at the injector, and at the final focus, and consideration of simple equations of state and relations for ion stoppin… more
Date: May 13, 2005
Creator: Barnard, J. J.; Briggs, R. J.; Callahan, D. A.; Davidson, R. C.; Friedman, A.; Grisham, L. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Final Report 02-ERD-033: Rapid Resolidification of Metals using Dynamic Compression

Description: The purpose of this project is to develop a greater understanding of the kinetics involved during a liquid-solid phase transition occurring at high pressure and temperature. Kinetic limitations are known to play a large role in the dynamics of solidification at low temperatures, determining, e.g., whether a material crystallizes upon freezing or becomes an amorphous solid. The role of kinetics is not at all understood in transitions at high temperature when extreme pressures are involved. In or… more
Date: February 11, 2005
Creator: Streitz, F. H.; Nguyen, J. H.; Orlikowski, D.; Minich, R.; Moriarty, J. A. & Holmes, N. C.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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The Limits of Quintessence

Description: We present evidence that the simplest particle-physics scalar-field models of dynamical dark energy can be separated into distinct behaviors based on the acceleration or deceleration of the field as it evolves down its potential towards a zero minimum. We show that these models occupy narrow regions in the phase-plane of w and w', the dark energy equation-of-state and its time-derivative in units of the Hubble time. Restricting an energy scale of the dark energy microphysics limits how closely … more
Date: May 24, 2005
Creator: Caldwell, R.R. & Linder, Eric V.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Determination of Longitudinal Phase Space in SLAC Main Accelerator Beams

Description: In the E164 Experiment at that Stanford Linear Accelerator Center (SLAC), we drive plasma wakes for electron acceleration using 28.5 GeV bunches from the main accelerator. These bunches can now be made with an RMS length of 12 microns, and accurate direct measurement of their lengths is not feasible shot by shot. Instead, we use an indirect technique, measuring the energy spectrum at the end of the linac and comparing with detailed simulations of the entire machine. We simulate with LiTrack, a … more
Date: June 7, 2005
Creator: Barnes, C.; Decker, F. J.; Emma, P.; Hogan, M. J.; Iverson, R.; Krejcik, P. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Luminosity Loss due to Beam Distortion and the Beam-Beam Instability

Description: In a linear collider, sources of emittance dilution such as transverse wakefields or dispersive errors will couple the vertical phase space to the longitudinal position within the beam (the so-called ''banana effect''). When the Intersection Point (IP) disruption parameter is large, these beam distortions will be amplified by a single bunch kink instability which will lead to luminosity loss. We study this phenomena both analytically using linear theory and via numerical simulation. In particul… more
Date: June 30, 2005
Creator: Wu, Juhao; Raubenheimer, T. O.; Chao, A. W.; Seryi, A. & Sramek, C. K.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Computer Algorithm for Longitudinal Single Bunch Stability Study in a Storage Ring

Description: We propose a new method for simulation study of the nonlinear interaction of a single bunch and accelerator vacuum chamber elements. We numerically solve the Fokker-Planck time-domain equation for the phase-space distribution function. Original implicit finite-difference scheme is used. The method is very stable and free of the ''numerical'' diffusion, distortion, or modulation. We introduce quasi-Green function to describe the wake field potentials of bunches of any shape. This allows to get h… more
Date: June 22, 2005
Creator: Novokhatski, Sasha
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Phase-Space Density Analysis of the AE-8 Traped Electron and the AP-8 Trapped Proton Model Environments

Description: The AE-8 trapped electron and the AP-8 trapped proton models are used to examine the L-shell variation of phase-space densities for sets of transverse (or 1st) invariants, {mu}, and geometrical invariants, K (related to the first two adiabatic invariants). The motivation for this study is twofold: first, to discover the functional dependence of the phase-space density upon the invariants; and, second, to explore the global structure of the radiation belts within this context. Variation due to p… more
Date: August 2005
Creator: Cayton, Thomas E.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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''Atomic Optics'': Nonimaging Optics on the Nanoscale

Description: This is the final report for a one year close out extension of our basic research program that was established at the University of Chicago more than sixteen years ago to explore and develop the optical sub-discipline that has come to be known as ''nonimaging optics''. This program has been extremely fruitful, having both broadened the range of formalism available for workers in this field and led to the discovery of many new families of optical devices. These devices and techniques have applic… more
Date: January 15, 2005
Creator: O'Gallagher, Roland Winston Joseph
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Theory for dynamical self arrest and gelation in microemulsions and the block copolymer systems

Description: The main purpose of this work is to investigate the glassy behavior of microemulsions and block copolymers. The origin of glassy behavior in microemulsions and block copolymers is frustration due to a competition between short-range interaction and long range interaction. According to the charge frustrated Ising model, the competition between ferromagnetic interaction and antiferromagnetic interaction is the origin of frustration in microemulsions. The competition between entropic effects and s… more
Date: May 1, 2005
Creator: Wu, Sangwook
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
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Simulating Electron Clouds in Heavy-Ion Accelerators

Description: Contaminating clouds of electrons are a concern for most accelerators of positive-charged particles, but there are some unique aspects of heavy-ion accelerators for fusion and high-energy density physics which make modeling such clouds especially challenging. In particular, self-consistent electron and ion simulation is required, including a particle advance scheme which can follow electrons in regions where electrons are strongly-, weakly-, and un-magnetized. They describe their approach to su… more
Date: April 7, 2005
Creator: Cohen, R. H.; Friedman, A.; Kireeff Covo, M.; Lund, S. M.; Molvik, A. W.; Bieniosek, F. M. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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A Short Introduction to General Gyrokinetic Theory

Description: Interesting plasmas in the laboratory and space are magnetized. General gyrokinetic theory is about a symmetry, gyro-symmetry, in the Vlasov-Maxwell system for magnetized plasmas. The most general gyrokinetic theory can be geometrically formulated. First, the coordinate-free, geometric Vlasov-Maxwell equations are developed in the 7-D phase space, which is defined as a fiber bundle over the space-time. The Poincar{copyright}-Cartan-Einstein 1-form pullbacked onto the 7-D phase space determines … more
Date: February 14, 2005
Creator: Qin, H.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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On the Existence of Our Metals-Based Civilization: I. Phase Space Analysis

Description: The stability of the barrier layers of bilayer passive films that form on metal and alloy surfaces, when in contact with oxidizing aqueous environments, is explored within the framework of the Point Defect Model (PDM) using phase-space analysis (PSA), in which the rate of growth of the barrier layer into the metal, (dL{sup +}/dt), and the barrier layer dissolution rate, (dL{sup -}/dt), are plotted simultaneously against the barrier layer thickness. A point of intersection of dL{sup -}/dt with d… more
Date: June 22, 2005
Creator: Macdonald, D.D.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Phase-Space Density Analyses of the AE-8 Trapped Electron and the AP-8 Trapped Proton Model Environments

Description: The AE-8 trapped electron and the AP-8 trapped proton models are used to examine the L-shell variation of phase-space densities for sets of transverse (or 1st) invariants, {mu}, and geometrical invariants, K (related to the first two adiabatic invariants). The motivation for this study is twofold: first, to discover the functional dependence of the phase-space density upon the invariants; and, second, to explore the global structure of the radiation belts within this context. Variation due to p… more
Date: August 12, 2005
Creator: Cayton, T. E.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Space-Charge Transport Limits in Periodic Channels

Description: It has been empirically observed in both experiments and particle-in-cell simulations that space-charge-dominated beams suffer strong emittance growth and particle losses in alternating gradient quadrupole transport channels when the undepressed phase advance {sigma}{sub 0} increases beyond about 85{sup o} per lattice period. Although this criteria has been used extensively in practical designs of intense beam transport lattices, no theory exists that explains the limit. We propose a mechanism … more
Date: May 16, 2005
Creator: Lund, S M & Chawla, S R
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Tomographic Measurement of Longitudinal Emittance Growth Due to Stripping Foils.

Description: During beam acceleration in the Brookhaven accelerator complex, heavy ions are stripped of their electrons in several steps. Depending on the properties of the stripping foils, this process results in an increased energy spread and longitudinal emittance growth. A tomographic phase space reconstruction technique has been applied to measure the associated emittance growth for different stripping foil materials.
Date: May 16, 2005
Creator: Montag, C.; Ahrens, L. & Thieberger, P.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Angular correlations in beauty production at the Tevatron at sqrt(s) = 1.96 TeV

Description: Measurements of the b quark production cross section at the Tevatron and at Hera in the final decades of the 20th century have consistently yielded higher values than predicted by Next-to-Leading Order (NLO) QCD. This discrepancy has led to a large efforts by theorists to improve theoretical calculations of the cross sections and simulations of b quark production. As a result, the difference between theory and experiment has been much reduced. New measurements are needed to test the development… more
Date: June 1, 2005
Creator: Wijngaarden, Daniel A. & Nijmegen, /Radboud U.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
open access

Bunch Length Measurements at the ATF Damping Ring in April 2000

Description: We want to accurately know the energy spread and bunch length dependence on current in the ATF damping ring. One reason is to know the strength of the impedance: From the energy spread measurements we know whether or not we are above the threshold to the microwave instability, and from the energy spread and bunch length measurements we find out the extent of potential-well bunch lengthening (PWBL). Another reason for these measurements is to help in our understanding of the intra-beam scatterin… more
Date: December 19, 2005
Creator: Bane, K. L. F.; Naito, T.; Okugi, T. & Urakawa, J.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Computation of the Longitudinal Space Charge Effect in Photoinjectors

Description: The LCLS Photoinjector produces a 100A, 10 ps long electron bunch which is later compressed down to 230 fs to produce the peak current required for generating SASE radiation. SASE saturation will be reached in the LCLS only if the emittance and uncorrelated energy spread remain respectively below 1.2 mm.mrad and 5.10{sup -4}. This high beam quality will not be met if the Longitudinal Space Charge (LSC) instability develops in the injector and gets amplified in the compressors. The LSC instabili… more
Date: May 9, 2005
Creator: Emma, P.; Huang, Z.; Limborg-Deprey, C.; Welch, J. J. & Wu, J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Uncorrelated Energy Spread and Longitudinal Emittance of a Photo injector Beam

Description: Longitudinal phase space properties of a photoinjector beam are important in many areas of high-brightness beam applications such as bunch compression, transverse-to-longitudinal emittance exchange, and high-gain free-electron lasers. In this paper, we discuss both the rf and the space charge contributions to the uncorrelated energy spread of the beam generated from a laser-driven rf gun. We compare analytical expressions for the uncorrelated energy spread and the longitudinal emittance with nu… more
Date: May 25, 2005
Creator: Huang, Z; Dowell, D.; Emma, P.; Limborg-Deprey, C.; Stupakov, G. & Wu, J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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The modeling of RF stacking of protons in the Accumulator

Description: When the Run2 collider program is terminated in 2009, the present pbar source will be available for other usages. One possible application is to convert the Antiproton Accumulator to a proton accumulator so that the beam power from the Main Injector could be greatly enhanced [1]. The Accumulator has the unique feature of very large momentum acceptance. It is possible to stack 3-4 Booster batches in the longitudinal phase space before transferring them to the Main Injector or Recycler. This note… more
Date: June 1, 2005
Creator: Yoon, Phil S.; McGinnis, David P. & Chou, Weiren
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Discrete Particle Noise in Particle-in-Cell Simulations of Plasma Microturbulence

Description: Recent gyrokinetic simulations of electron temperature gradient (ETG) turbulence with flux-tube continuum codes vs. the global particle-in-cell (PIC) code GTC yielded different results despite similar plasma parameters. Differences between the simulations results were attributed to insufficient phase-space resolution and novel physics associated with toroidicity and/or global simulations. We have reproduced the results of the global PIC code using the flux-tube PIC code PG3EQ, thereby eliminati… more
Date: May 24, 2005
Creator: Nevins, W M; Dimits, A & Hammett, G
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Status of Continuum Edge Gyrokinetic Code Physics Development

Description: We are developing an edge gyro-kinetic continuum simulation code to study the boundary plasma over a region extending from inside the H-mode pedestal across the separatrix to the divertor plates. A 4-D ({psi}, {theta}, {epsilon}, {mu}) version of this code is presently being implemented, en route to a full 5-D version. A set of gyrokinetic equations[1] are discretized on computational grid which incorporates X-point divertor geometry. The present implementation is a Method of Lines approach whe… more
Date: May 31, 2005
Creator: Xu, X Q; Xiong, Z; Dorr, M R; Hittinger, J A; Kerbel, G D; Nevins, W M et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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