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Implications of beam phase and RFSUM measured near transition

Description: A technique using RF bucket reduction for acquiring information about the particle distribution in longitudinal phase space has been applied in the Fermilab Booster. Data sets were obtained at six important time intervals of a Booster cycle for three different beam intensities. Controlled RF bucket reduction also provides other opportunities for beam manipulation.
Date: April 7, 2004
Creator: Yang, Xi & MacLachlan, James
Partner: UNT Libraries Government Documents Department

The velocity peaks in the cold dark matter spectrum on earth

Description: The cold dark matter spectrum on earth is expected to have peaks in velocity space. We obtain estimates for the sizes and locations of these peaks. To this end we have generalized the secondary infall model of galactic halo formation to include angular momentum of the dark matter particles. This new model is still spherically symmetric and it has self-similar solutions. Our results are relevant to direct dark matter search experiments.
Date: April 13, 1995
Creator: Sikivie, P.; Tkachev, I.I. & Wang, Y.
Partner: UNT Libraries Government Documents Department

Betatron motion with coupling of horizontal and vertical degrees of freedom

Description: The Courant-Snyder parameterization of one-dimensional linear betatron motion is generalized to two-dimensional coupled linear motion. To represent the 4 x 4 symplectic transfer matrix the following ten parameters were chosen: four beta-functions, four alpha-functions and two betatron phase advances which have a meaning similar to the Courant-Snyder parameterization. Such a parameterization works equally well for weak and strong coupling and can be useful for analysis of coupled betatron motion in circular accelerators as well as in transfer lines. Similarly, the transfer matrix, the bilinear form describing the phase space ellipsoid and the second order moments are related to the eigen-vectors. Corresponding equations can be useful in interpreting tracking results and experimental data.
Date: November 21, 2002
Creator: Bogacz, S. A. & Lebedev, V. A.
Partner: UNT Libraries Government Documents Department

Hybrid Ray/Wave Optics for Laser-Plasma Interaction

Description: This aim of this FY 1998 LDRD project was to create a computational tool which bridges the gap between wave and ray optical regimes, important for application areas such as laser propagation in plasma and multimode photonics. We used phase space methods, where a set of rays distributed in a particular way in position and angle retain many essential features of wave optics. To characterize and enhance our understanding of the method, we developed a GUI-based photonics tool which can analyze light propagation in systems with a variety of axial and transverse refractive index distributions.
Date: February 18, 1999
Creator: Ratowsky, R.P.; Kallman, J.S.; Afeyan, B.B. & Feit, M.D.
Partner: UNT Libraries Government Documents Department


Description: In recent years, longitudinal phase-space tomography has become a useful diagnostic tool in the domain of particle accelerators. A computer code has been developed to visualize and quantify dynamic effects in longitudinal phase space, like transition crossing and rebucketing. This code is capable of reconstructing the longitudinal phase space distribution during turn-by-turn parameter changes such as RF phase and voltage jumps. This paper describes the reconstruction code as well as recent applications at the Relativistic Heavy Ion Collider (RHIC).
Date: June 2, 2002
Partner: UNT Libraries Government Documents Department

Flash X-Ray Injector Study

Description: The study described in this report1 models the FXR injector from the cathode to the exit of the injector. The calculations are compared to actual experimental measurements, table 1. In these measurements the anode voltage was varied by changing the Marks-Bank charging voltage. The anode-cathode spacing was varied by adjusting the location of the cathode in hopes of finding an island of minimum emittance (none found). The bucking coil current was set for zero field on the cathode. In these measurements, a pepper-pot mask was inserted into FXR at beam bug 135 and viewed downstream via a wiggle probe diagnostic at cell gap J21, figure 1. The observed expansion of the beamlets passing through the mask of known geometric layout and hole size allow a calculation of the phase space beam properties.
Date: March 26, 2004
Creator: Paul, A C
Partner: UNT Libraries Government Documents Department

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.
Partner: UNT Libraries Government Documents Department

J/psi Production in Quark-Gluon Plasma

Description: We study J/{psi} production at RHIC and LHC energies with both initial production and regeneration. We solve the coupled set of transport equation for the J/{psi} distribution in phase space and the hydrodynamic equation for evolution of quark-gluon plasma. At RHIC, continuous regeneration is crucial for the J/{psi} momentum distribution while the elliptic flow is still dominated by initial production. At LHC energy, almost all the initially created J/{psi}s are dissociated in the medium and regeneration dominates the J/{psi} properties.
Date: October 30, 2006
Creator: Yan, Li; Zhuang, Pengfei & Xu, Nu
Partner: UNT Libraries Government Documents Department

Real time correlation function in a single phase spaceintegral--beyond the linearized semiclassical initial valuerepresentation

Description: It is shown how quantum mechanical time correlation functions [defined, e.g., in Eq. (1.1)] can be expressed, without approximation, in the same form as the linearized approximation of the semiclassical initial value representation (LSC-IVR), or classical Wigner model, for the correlation function [cf. Eq. (2.1)], i.e., as a phase space average (over initial conditions for trajectories) of the Wigner functions corresponding to the two operators. The difference is that the trajectories involved in the LSC-IVR evolve classically, i.e., according to the classical equations of motion, while in the exact theory they evolve according to generalized equations of motion that are derived here. Approximations to the exact equations of motion are then introduced to achieve practical methods that are applicable to complex (i.e., large) molecular systems. Four such methods are proposed in the paper--the full Wigner dynamics (full WD) and the 2nd order WD based on 'Winger trajectories', and the full Donoso-Martens dynamics (full DMD) and the 2nd order DMD based on 'Donoso-Martens trajectories'--all of which can be viewed as generalizations of the original LSC-IVR method. Numerical tests of these four versions of this new approach are made for two anharmonic model problems, and for each the momentum autocorrelation function (i.e., operators linear in coordinate or momentum operators) and the force autocorrelation function (non-linear operators) have been calculated. These four new approximate treatments are indeed seen to be significant improvements to the original LSC-IVR approximation.
Date: July 10, 2007
Creator: Liu, Jian & Miller, William H.
Partner: UNT Libraries Government Documents Department

Recirculation in multiple wave conversions

Description: A one-dimensional multiple wave-conversion model is constructed that allows energy recirculation in ray phase space. Using a modular eikonal approach, the connection coefficients for this model are calculated by ray phase-space methods. Analytical results (confirmed numerically) show that all connection coefficients exhibit interference effects that depend on an interference phase, calculated from the coupling constants and the area enclosed by the intersecting rays. This conceptual model, which focuses on the topology of intersecting rays in phase space, is used to investigate how mode conversion between primary and secondary waves is modified by the presence of a tertiary wave.
Date: July 30, 2008
Creator: Kaufman, A. N.; Brizard, A.J.; Kaufman, A.N. & Tracy, E.R.
Partner: UNT Libraries Government Documents Department

Phase Space Dissimilarity Measures for Structural Health Monitoring

Description: A novel method for structural health monitoring (SHM), known as the Phase Space Dissimilarity Measures (PSDM) approach, is proposed and developed. The patented PSDM approach has already been developed and demonstrated for a variety of equipment and biomedical applications. Here, we investigate SHM of bridges via analysis of time serial accelerometer measurements. This work has four aspects. The first is algorithm scalability, which was found to scale linearly from one processing core to four cores. Second, the same data are analyzed to determine how the use of the PSDM approach affects sensor placement. We found that a relatively low-density placement sufficiently captures the dynamics of the structure. Third, the same data are analyzed by unique combinations of accelerometer axes (vertical, longitudinal, and lateral with respect to the bridge) to determine how the choice of axes affects the analysis. The vertical axis is found to provide satisfactory SHM data. Fourth, statistical methods were investigated to validate the PSDM approach for this application, yielding statistically significant results.
Date: November 1, 2011
Creator: Bubacz, Jacob A; Chmielewski, Hana T; Pape, Alexander E; Depersio, Andrew J; Hively, Lee M; Abercrombie, Robert K et al.
Partner: UNT Libraries Government Documents Department

Lattice Modeling and Calibration with Turn-by-Turn Orbit Data

Description: A new method that explores turn-by-turn BPM data to calibrate lattice models of accelerators is proposed. The turn-by-turn phase space coordinates at one location of the ring are first established using data from two BPMs separated by a simple section with a known transfer matrix, such as a drift space. The phase space coordinates are then tracked with the model to predict positions at other BPMs, which can be compared to measurements. The model is adjusted to minimize the difference between the measured and predicted orbit data. BPM gains and rolls are included as fitting variables. This technique can be applied to either the entire or a section of the ring. We have tested the method experimentally on a part of the SPEAR3 ring.
Date: April 5, 2011
Creator: Huang, X.; Sebek, J.; Martin, D. & /SLAC
Partner: UNT Libraries Government Documents Department

Gyrokinetics Simulation of Energetic Particle Turbulence and Transport

Description: Progress in research during this year elucidated the physics of precession resonance and its interaction with radial scattering to form phase space density granulations. Momentum theorems for drift wave-zonal flow systems involving precession resonance were derived. These are directly generalizable to energetic particle modes. A novel nonlinear, subcritical growth mechanism was identified, which has now been verified by simulation. These results strengthen the foundation of our understanding of transport in burning plasmas
Date: September 21, 2011
Creator: Diamond, Patrick H.
Partner: UNT Libraries Government Documents Department

Diffusion in phase space

Description: In order to study diffusion in any region of phase space containing nested closed curves we choose action-angle variables, {gamma}, J. the action J labels each closed phase curve and is equal to its area divided by 2{pi}. We can introduce rectangular variables Q,P by the equations Q=(2J){sup 1/2}sin{gamma}, P=(2J){sup 1/2}cos{gamma}, where the angle variable {gamma} is measured clockwise from the P-axis. The phase curves are circles in the Q,P plane with radius (2J){sup 1/2}. We assume that the motion consists of a Hamiltonian motion along a curve of fixed J (in the original coordinate system and in the system Q,P) plus a diffusion and a damping which can change the value of J. Now consider a system of particles described by a density {rho}(J,t), so that the number of particles between the curves J and J+dJ is dN={rho}(J,t)dJ. These cN particles are distributed uniformly in the phase space between the curves J and J+dJ.
Date: April 5, 1993
Creator: Symon, K.
Partner: UNT Libraries Government Documents Department

Introduction to collective instabilities----longitudinal and transverse

Description: These topics are covered: 1 Wakes and impedances 1.1 Wake functions 1.2 Coupling impedances 2 Longitudinal phase space 2.1 Equations of motion 2.2 Vlasov equation 3 Potential-well distortion 4 Longitudinal microwave instability 4.1 Dispersion relation 4.2 Landau damping 4.3 Self-bunching 4.4 Overshoot and bunch lengthening 4.5 Observation 5 Longitudinal coupled-bunch instabilities 5.1 Sacherer integral equation 5.2 Time domain 5.3 Rf-detuning and Robinson's stability criteria 6 Transverse instabilities 6.1 Sacherer integral equation 6.2 Solution of Sacherer integral equations 6.1 Sacherer sinusoidal modes of excitation 6.2 Chromaticity frequency shift 7 Transverse coupled-bunch instabilities 7.1 Resistive wall 7.2 Narrow resonances 8 Head-tail instabilities 9 Mode-mixing 9.1 Transverse 9.2 Longitudinal. Exercises are included.
Date: October 1, 1998
Creator: Ng, King-Yuen
Partner: UNT Libraries Government Documents Department

The Quest for a High Performance Boltzmann Transport Solver

Description: A 3-d Boltzmann transport code developed at Lawrence Livermore National Laboratory exploits concurrency (problem permitting) with respect to all phase space variables represented by direction, position and energy. To demonstrate the capabilities of the code, a highly resolved Boltzmann transport calculation with 27.6 billion unknowns (332 billion discretization points) was performed on 4992 processors of the IBM RS/6000 SP ASCI Blue machine at Lawrence Livermore National Laboratory. Detailed performance measurements were collected during this calculation. Analyzing the timing data revealed a relatively modest performance, i.e. obtained fraction of peak performance. A detailed study of the performance data confirmed that this modest performance was caused by low utilization of local processor performance, as well as low parallel efficiency of the intrinsically sequential sweep procedure. Both issues and their ramifications will be addressed in this paper.
Date: September 1, 1999
Creator: Brown, P.N.; Chang, B.; Hanebutte, U.R. & Woodward, C.S.
Partner: UNT Libraries Government Documents Department

Particle motion in the stable region near the edge of a linear sum resonance stopband

Description: This paper studies the particle motion when the tune is in the stable region close to the edge of linear sum resonance stopband. Results are found for the tune and the beta functions. Results are also found for the two solutions of the equations of motion. The results found are shown to be also valid for small accelerators where the large accelerator approximation may not be used.
Date: December 1, 1995
Creator: Parzen, G.
Partner: UNT Libraries Government Documents Department

Spectral analysis of reltivistic bunched beams

Description: Particles in a storage ring are oscillating in the longitudinal and transverse dimensions, and therefore, the frequency domain is natural for analyzing many beam generated signals. Information ranging from oscillation frequencies to beam phase space distributions can be extracted from the spectral content of these signals. The spectrum of a single particle is like a Green`s function, and it is the key to understanding the spectrum produced by a beam. Three separate cases are consider in an order of increasing complexity: (1) constant revolution frequency, (2) Frequency Modulation introduced by synchrotron oscillations, and (3) Amplitude Modulation introduced by betatron oscillations.
Date: May 1, 1996
Creator: Siemann, R.H.
Partner: UNT Libraries Government Documents Department

A study of betatron and momentum collimators in RHIC

Description: The Relativistic Heavy Ion Collider (RHIC) has two interaction regions where {beta}* = 1--2m, with large detectors PHENIX and STAR. The transverse and longitudinal emittances are expected to double in size between one to two hours due to intra-beam scattering which may lead to transverse beam loss. Primary betatron collimators are positioned in the ring to allow efficient removal of particles with large betatron amplitudes. The authors have investigated distributions and losses coming from the out-scattered particles from the primary collimators, as well as the best positions for the secondary momentum and betatron collimators.
Date: July 1, 1997
Creator: Trbojevic, D.; Stevens, A.J.; Harrison, M.A.; Dell, F. & Peggs, S.
Partner: UNT Libraries Government Documents Department