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EVIDENCE FOR A T = 0 RESONANCE IN THE V * SYSTEM

Description: In previous letters the authors have reported a {Sigma}{pi} resonance observed through the study of the interaction of 1.15-Bev/c K{sup -} meons in hydrogen in the Lawrence Radiation Laboratory 15-in. bubble chamber. They now wish to report the results of the study of the three reactions: (1) K{sup -} + p {yields} {Sigma}{sup +} + {pi}{sup -} + {pi}{sup -} + {pi}{sup +}; (2) K{sup -} + p {yields} {Sigma}{sup -} + {pi}{sup +} + {pi}{sup +} + {pi}{sup -}; and (3) K{sup -} + p {yields} {Sigma}{sup… more
Date: April 28, 1961
Creator: Alston, Margaret H.; Alvarez, Luis W.; Eberhard, Philippe; Good,Myron L.; Graziano, William; Ticho, Harold K. et al.
Partner: UNT Libraries Government Documents Department
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Use beam steering dipoles to minimize aberrations associated with off-centered transit through the induction bunching module. Design an improved NDCX-I drift compression section to make best use of the new bunching module to optimize planned initial NDCX-I target experiments

Description: This milestone has been met by: (1) calculating steering solutions and implementing them in the experiment using the three pairs of crossed magnetic dipoles installed in between the matching solenoids, S1-S4. We have demonstrated the ability to center the beam position and angle to<1 mm and<1 mrad upstream of the induction bunching module (IBM) gap, compared to uncorrected beam offsets of several millimeters and milli-radians. (2) Based on LSP and analytic study, the new IBM, which has tw… more
Date: March 28, 2008
Creator: HIFS-VNL; Seidl, Peter; Seidl, P.; Barnard, J.; Bieniosek, F.; Coleman, J. et al.
Partner: UNT Libraries Government Documents Department
open access

An Iterative Phase-Space Explicit Discontinuous Galerkin Method for Stellar Radiative Transfer in Extended Atmospheres

Description: A phase-space discontinuous Galerkin (PSDG) method is presented for the solution of stellar radiative transfer problems. It allows for greater adaptivity than competing methods without sacrificing generality. The method is extensively tested on a spherically symmetric, static, inverse-power-law scattering atmosphere. Results for different sizes of atmospheres and intensities of scattering agreed with asymptotic values. The exponentially decaying behavior of the radiative field in the diffusive-… more
Date: January 28, 2004
Creator: de Almeida, V.F.
Partner: UNT Libraries Government Documents Department
open access

Meshless Solution of the Vlasov Equation Using a Low Discrepancy Sequence

Description: A good method for solving the nonlinear Vlasov equation is the semi-Lagrangian algorithm, in which the phase space density is represented by its values on a fixed Cartesian grid with interpolation to off-grid points. At each time step, orbits are followed backward from grid points. Since this method is expensive with phase space dimension D > 2, we seek a more efficient discretization of the density. Taking a cue from the theory of numerical quadrature in high dimensions, we explore the idea… more
Date: January 28, 2009
Creator: Warnock, R. L.; Ellison, J. A.; Heinemann, K. & Zhang, G. Q.
Partner: UNT Libraries Government Documents Department
open access

Amplification of current density modulation in a FEL with an infinite electron beam

Description: We show that the paraxial field equation for a free electron laser (FEL) in an infinitely wide electron beam with {kappa}-2 energy distribution can be reduced to a fourth ordinary differential equation (ODE). Its solution for arbitrary initial phase space density modulation has been derived in the wave-vector domain. For initial current modulation with Gaussian profile, close form solutions are obtained in space-time domain. In developing an analytical model for a FEL-based coherent electron co… more
Date: March 28, 2011
Creator: Wang, G.; Litvinenko, V. N. & Webb, S. D.
Partner: UNT Libraries Government Documents Department
open access

Charge Separation for Muon Collider Cooling

Description: Most schemes for six dimensional muon ionization cooling work for only one sign. It is then necessary to have charge separation prior to that cooling. Schemes of charge separation using bent solenoids are described, and their simulated performances reported. It is found that for efficient separation, it should take place at somewhat higher momenta than commonly used for the cooling. Charge separation using bent solenoids can be effective if carefully designed. Bent solenoids can generate disper… more
Date: March 28, 2011
Creator: Palmer, R. B.
Partner: UNT Libraries Government Documents Department
open access

Comparison of 1D and 2D CSR Models with Application to the FERMI@ELETTRA Bunch Compressors

Description: We compare our 2D mean field (Vlasov-Maxwell) treatment of coherent synchrotron radiation (CSR) effects with 1D approximations of the CSR force which are commonly implemented in CSR codes. In our model we track particles in 4D phase space and calculate 2D forces [1]. The major cost in our calculation is the computation of the 2D force. To speed up the computation and improve 1D models we also investigate approximations to our exact 2D force. As an application, we present numerical results for t… more
Date: March 28, 2011
Creator: Bassi, G.; Ellison, J. A. & Heinemann, K.
Partner: UNT Libraries Government Documents Department
open access

Tapered Six-Dimensional Cooling Channel for a Muon Collider

Description: A high-luminosity muon collider requires a reduction of the six-dimensional emittance of the captured muon beam by a factor of {approx} 10{sup 6}. Most of this cooling takes place in a dispersive channel that simultaneously reduces all six phase space dimensions. We describe a tapered 6D cooling channel that should meet the requirements of a muon collider. The parameters of the channel are given and preliminary simulations are shown of the expected performance. A complete scheme for cooling a m… more
Date: March 28, 2011
Creator: Palmer, R. B. & Fernow, R. C.
Partner: UNT Libraries Government Documents Department
open access

APPLYING CASCADED PARAMETER SCAN TO STUDY TOP-OFF SAFETY IN NSLS-II STORAGE RING

Description: In this paper we introduce a new algorithm, the cascaded parameter scan method, to efficiently carry out the scan over magnet parameters in the safety analysis for storage ring top-off injection. In top-off safety analysis, one must track particles populating phase space through a beamline containing magnets and apertures and clearly demonstrate that for all possible magnet settings and errors, all particles are lost on scrapers within the properly shielded region. In the usual approach, the nu… more
Date: March 28, 2011
Creator: Li, Y.
Partner: UNT Libraries Government Documents Department
open access

Seeding Coherent Radiation Sources with Sawtooth Modulation

Description: Seed radiation sources have the ability to increase longitudinal coherence, decrease saturation lengths, and improve performance of tapering, polarization control and other FEL features. Typically, seeding schemes start with a simple sinusoidal modulation, which is manipulated to provide bunching at a high harmonic of the original wavelength. In this paper, we consider seeding from sawtooth modulations. The sawtooth creates a clean phase space structure, providing a maximal bunching factor with… more
Date: March 28, 2012
Creator: Ratner, Daniel & Chao, Alex
Partner: UNT Libraries Government Documents Department
open access

Plasma-Based Studies on 4th Generation Light Sources

Description: The construction of a short pulse tunable x-ray laser source will be a watershed for plasma-based and warm dense matter research. The areas we will discuss below can be separated broadly into warn dense matter (WDM) research, laser probing of near solid density plasmas, and laser-plasma spectroscopy of ions in plasmas. The area of WDM refers to that part of the density-temperature phase space where the standard theories of condensed matter physics and/or plasma statistical physics are invalid. … more
Date: November 28, 2000
Creator: Lee, R. W.; Baldis, H. A.; Cauble, R. C.; Landen, O. L.; Wark, J. S.; Ng, A. et al.
Partner: UNT Libraries Government Documents Department
open access

Six Dimensional Bunch Merging for Muon Collider Cooling

Description: A muon collider requires single, intense, muon bunches with small emittances in all six dimensions. It is most efficient to initally phase-rotate the muons into many separate bunches, cool these bunches in six dimensions (6D), and, when cool enough, merge them into single bunches (one of each sign). Previous studies only merged in longitudinal phase space (2D). In this paper we describe merging in all six dimensions (6D). The scheme uses rf for longitudinal merging, and kickers and transports w… more
Date: March 28, 2011
Creator: Palmer, R. B. & Fernow, R. C.
Partner: UNT Libraries Government Documents Department
open access

Case A Binary Evolution

Description: We undertake a comparison of observed Algol-type binaries with a library of computed Case A binary evolution tracks. The library consists of 5500 binary tracks with various values of initial primary mass M{sub 10}, mass ratio q{sub 0}, and period P{sub 0}, designed to sample the phase-space of Case A binaries in the range -0.10 {le} log M{sub 10} {le} 1.7. Each binary is evolved using a standard code with the assumption that both total mass and orbital angular momentum are conserved. This code … more
Date: March 28, 2001
Creator: Nelson, C A & Eggleton, P P
Partner: UNT Libraries Government Documents Department
open access

A core-particle model for periodically focused ion beams withintense space-charge

Description: A core-particle model is derived to analyze transverse orbits of test particles evolving in the presence of a core ion beam that has uniform density within an elliptical cross-section. The model can be applied to both quadrupole and solenoidal focused beams in periodic or aperiodic lattices. Efficient analytical descriptions of electrostatic space-charge fields external to the beam core are derived to simplify model equations. Image charge effects are analyzed for an elliptical beam centered in… more
Date: August 28, 2006
Creator: Lund, Steven M.; Barnard, John J.; Bukh, Boris; Chawla, SurgreevR. & Chilton, Sven H.
Partner: UNT Libraries Government Documents Department
open access

Experimental Studies of Temporal Electron Beam Shaping at the DUV-FEL Accelerator

Description: The photoinjectors for future short wavelength high brightness accelerator driven light sources need to produce an electron beam with ultra-low emittance. At the DUVFEL facility at BNL, we studied the effect of longitudinally shaping the photocathode laser pulses on the electron beam dynamics. We report on measurements of the longitudinal phase space distributions and the time-resolved transverse beam parameters for both a Gaussian and a flat-top temporal laser pulse profile.
Date: September 28, 2005
Creator: Loos, H.; Doweel, D.; Sheehy, B.; Shen, Y.; Tsang, T.; Wang, X. et al.
Partner: UNT Libraries Government Documents Department
open access

Measurements of the Decays B0->D0barppbar, B0->D*0ppbar, B0->D-ppbar\pi+, and B0->D*-ppbar\pi+

Description: The authors present measurements of branching fractions of B{sup 0} decays to multi-body final states containing protons, based on 232 million {Upsilon}(4S) {yields} B{bar B} decays collected with the BABAR detector at the SLAC PEP-II asymmetric-energy B factory. They measure the branching fractions {Beta}(B{sup 0} {yields} {bar D}{sup 0} p{bar p}) = (1.13 {+-} 0.06 {+-} 0.08) x 10{sup -4} {Beta}(B{sup 0} {yields} {bar D}*{sup 0} p{bar p}) = (1.01 {+-} 0.10 {+-} 0.09) x 10{sup -4}, {Beta}(B{sup… more
Date: July 28, 2006
Creator: Aubert, B.
Partner: UNT Libraries Government Documents Department
open access

Analysis of a third-order sum resonance

Description: It is worth considering an experiment on a sum resonance. I will give an analytic treatment of a third-order sum resonance. The treatment parallels that in LS-132 for the Walkinshaw difference resonance. Although the algebra is essentially the same as for the difference resonance, the sum resonance appears to have a richer structure.
Date: June 28, 1990
Creator: Symon, K.
Partner: UNT Libraries Government Documents Department
open access

Report of the SSC impedance workshop

Description: This workshop focused attention on the transverse, single-bunch instability and the detailed analysis of the broadband impedance which would drive it. Issues discussed included: (1) single bunch stability -- impact of impedance frequency shape, coupled-mode vs. fast blowup regimes, possible stopband structure; (2) numerical estimates of transverse impedance of inner bellows and sliding contact shielded bellows; (3) analytic estimates of pickup and kicker impedance contributions; and (4) feasibi… more
Date: October 28, 1985
Partner: UNT Libraries Government Documents Department
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