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ISABELLE: Brookhaven intersecting storage accelerators

Description: From seininar on high-energy accelerator science; Tokyo and Tsukuba, Japan (5 Nov 1973). The status of the ISABELLE project is briefly reviewed, and the design parameters are outlined including the lattice configuration, magnets. magnet power supply, injection, rf system, vacuum system, experimental areas and options. (WHK)
Date: January 1, 1973
Creator: Blewett, J.P.
Partner: UNT Libraries Government Documents Department

Wake field produced by a particle in the presence of conductive plates: a vehicle for the excitation of the coupled betatron-synchrotron instabilities

Description: Beam instabilities observed in ADONE were studied. The interaction of a single particle betatron oscillation with conductive plates was analyzed. First, Fourier analysis of the field source was performed, then the usual approach to determine the plate response was used by treating the plates as transmission lines. Finally, with a process of anti-transformation the total response to the oscillation of a single particle was constructed. The wake field decays over a distance which is of the order of magnitude of the length of the plates themselves. Nevertheless, the shape of the wake field depends on the terminating independence. Several cases, for instance matched, open and shorted plates are considered. (auth)
Date: May 22, 1973
Creator: Ruggiero, A.G.
Partner: UNT Libraries Government Documents Department

Report on the measurement of the total cross section and luminosity at Isabelle. A summary of existing CRISP reports

Description: Methods for measuring the total cross section ( sigma /sub T/) are discussed including measurement of sigma from the total interaction rate, measurement of sigma /sub T/ from the forward elastic cross section, measurement of sigma /sub T/ from the beam attenuation rate, and measurement of the nucleon- nucleon total cross section ratio. Several methods for determining the luminosity are considered including the Van der Meer method, using the intersection of a high BETA and low BETA beams, luminosity determination by beam attenuation, measurement of the Coulomb region in p-p collisions, Coulomb dissociation of N*(1236), and electron pair production in p-p collisions. (WHK)
Date: January 1, 1974
Creator: Marx, J.N.
Partner: UNT Libraries Government Documents Department

Correction coil for random magnetic field errors in a superconducting storage accelerator

Description: Some considerations are given on the relative size of the random nonlinear field errors in the magnets of a superconducting storage accelerator and of a conventional warm accelerator. A possible correction coil is presented for the random field errors in the magnets of a superconducting storage accelerator. This correction coil consists of 24 conductors spaced equally around a circle, 12 of which can be independently excited. Each conductor can carry a maximum current of 1000 A, and has the dimensions of 0.32 x 0.008 in. for a 40-kG magnet with a 4-in. aperture. (auth)
Date: November 12, 1973
Creator: Parzen, G.
Partner: UNT Libraries Government Documents Department

Brickwall effect

Description: A quantitative account of the brickwall effect is given. By combining the theory of the resistive wall instability- with the theory of a nonuniform incoherent tune shift, it is shown how the brickwall effect manifests itself as a limit on the current tune density (current/tune spread) at some critical stack width. A description of the effect in the CERN ISR is given. It is also shown, by an example, how the limiting current condition can be used in a certain class of storage ring design. (auth)
Date: September 18, 1973
Creator: Month, M.
Partner: UNT Libraries Government Documents Department

Effect of synchrotron motion on the closed orbit distortion in crossing beams

Description: When beams collide with non-zero crossing angles, there is a dipole component to the beam-beam force, thus introducing a closed orbit distortion. If the force experienced by a particle is antisymmetric about the collision center, then the distorted orbit still passes through the collision center but with a changed slope, resulting in a shift from the nominal crossing angle. This antisymmetry in the force occurs for coasting beams, while for bunched beams, it is the case for particles at the center of the bunches, assuming that the bunches overlap exactly around the collision center. The presence of synchrotron motion means that the beam- beam force experienced by a particle modulates as the particle moves back amd forth within the bunch. Specifically, a symmetric component to the force is introduced. If the synchrotron period is much longer tham the betatron period, the modulation of the force is adiabatic, and so the effect is a modulation of the closed orbit. The symmetric compoment of the dipole force causes; shift in the closed orbit at the collision center. This indicates a tendency for the beams to separate, which in turn changes the mature of the force between the two beams. The closed orbit shift is calculated. Some comments on self-consistency are made. It is indicated how under certain circumstances, a self-consistent solution may not exist. The case of SPEAR is considered. It is shown that for small crossing angles, the orbit shift at the collision center is larger than the beam size, indicating a major effect. Further-more, it is argued that a self-consistent solution cannot exist. For coasting beams, small angle crossings can be designed so that only the antisymmetric component of the dipole force is prcsemt. Thus, the predominant effect is a shift in the nominal crossing angle. (auth)
Date: January 29, 1974
Creator: Month, M.
Partner: UNT Libraries Government Documents Department

Interaction of a coasting beam and a bunched beam with frequency slip

Description: Collisions between a coasting beam and a bunched beam can be so arranged that a particle in the coasting beam collides with the bunched beam only intermittently. A particle thus interacts with a bunch for a given number of revolutions, say q, and then slips away into the interbunch space. The process, with each cycle taking say, n revolutions, then continues. The possible effects of this intermittient type force are considered. The linear stopbands introduced are dealt with in detail. Growth rates are obtained as a function of q, assuming a Gaussian fall-off in the force. The stabilizing influence of an azimuthally constant octupole field component is demonstrated. Isolated nonlinear resonances excited by the intermittent force are discussed. No quantitative treatment is given as far as concerns the stochastic nature of highly nonlinear systems. Also, the influence of feeding mechanisms, such as a time variation of the tune is neglected. If the number of revolutions between kicks, ~n is large, then there is the possibility of loss of correlation betveen kicks. The resulting diffusion is analyzed and diffusion rates are estimated. It was concluded that: (1) growth due to linear instabilities are effectively damped by making q large enough. The perturbation is turned on and off adiabatically and leaves no record of itself from cycle to cycle. The growth rate is linear in DELTA the beam-- beam linear tune shift per interaction and per revolution; (2) the diffusion induced by random processes causing the kicks to be uncorrelated produces a bearm growth rate which is quadratic in DELTA nu . Although it is smaller than the gradient stopband growth (for low q), it is essentially independent of tune (and so occurs for all particles) and it has no drop-off with q. In fact, for large q, it increases like q/sup ...
Date: January 1, 1973
Creator: Month, M. & Ruggiero, A.G.
Partner: UNT Libraries Government Documents Department