[en] As the design energy of new machines increases and the beampipe diameter decreases, the upper limit on the longitudinal and transverse coupling impedances for beam stability requirements become lower. It appears now that for a 20 TeV ring with a b = 2.5 cm beampipe that Z₁₁/n is about 1 ohm and Z/sub T/ is about 10⁸ ohm/m. (These parameters are of course machine design dependent.) The major sources of these impedances are resistive wall, bellows and step discontinuities, rf cavities, Lambertsons and kickers, and position monitor electrodes. In most cases, careful design and selection of materials can minimize the impedance contribution of individual components. In the case of beam position pickup electrodes, however, the basic design objective is to couple energy out of the beam. Since the nature of this coupling is frequency dependent, the real part of the coupling impedance (i.e., signal power) and the imaginary component (longitudinal stability impedance) are related by causality (the Kramer-Kroenig relation). The purpose of this note is to discuss the basic design of the pickup electrodes, the impedance calculations, and estimates for the Superconducting Super Collider

[en] In the SSC, the synchrotron radiation generated by the circulating beam will liberate photoelectrons from the chamber walls, which in turn will desorb the surface molecules. The photoelectron yields depend on the photon energy and the chamber material. Here we calculate the photon energy distribution of the synchrotron radiation for 20 TeV, SSC with 3 Tesla and 8 Tesla magnets. The total number of photoelectrons produced is calculated using the known photoelectron yield of Al and the photon energy distribution

[en] The dynamic aperture of the Tevatron has been calculated using the tracking program TEVLAT written by A. Russell. It is possible within TEVLAT to specify the magnetic coefficients up to b₅ and a₅ for each individual dipole and quadrupole in the lattice. In the case of dipoles the higher moments up to n = 14 are approximated, in calculating the non-linear effects, by the average values over all the dipoles. (This constraint is imposed by the limits on the available memory in the Fermilab Cyber. We do not believe that this approximation affects the results presented here.) Because TEVLAT allows the low order moments to be specified for each magnet individually it is possible to use the MTF measurements on the magnets and study the effect the ordering of the magnets in the lattice has on the dynamic aperture. 4 figs

[en] The discussions of the group covered the following topics: (1) magnetic imperfections in superconducting magnets; (2) theoretical models of single particle dynamics; (3) particle tracking; and (4) experimental studies relevant to the SSC project

[en] The SSC will require two entirely independent vacuum systems. One system will maintain the insulating vacuum for the superconducting magnets at pressures of <10^-5 torr where gas conduction introduces negligible heat load on the cyrogenic system. Similar systems have been successfully operated in 10^-7 and 10^-8 torr ranges at the Tevatron and in CBA full cell tests. No additional problems are envisioned. The second system, known as the Beam Vacuum System, will have to cope with new problems not present in previous proton colliders and its requirements will be treated in some detail in this report. They are: (a) low residual gas molecule density (pressure); (b) low Z/n parameter (low resistivity vacuum chamber with a minimum of discontinuities); and (c) removal of heat due to synchrotron radiation and due to the rf component of the circulating beam (1/2 R/sub s/I²)

[en] High luminosity will be necessary for the study of many of the new phenomena expected in the SSC energy region. Particle detectors, however, are limited in the number of simultaneous interactions which they can handle, and thus need a good duty cycle with collisions spread out in time to the greatest extent possible. To avoid the larger number of stored protons now thought to be required for continuous beams, we have considered bunched beams of protons crossing at a small angle. Plots are given of the dependence on bunch separation of the emittance, number of protons, etc., needed for 10³³cm^-2sec^-1. In order to minimize the number of stored protons (approx. 10¹⁴/ring), an emittance roughly ten times smaller than that presently achieved at high energies is required for a bunch separation of 6 meters (20 nsec)

[en] At the outset of the group's work, presentations and discussions served to introduce participants to the SSC features defining the RF system requirements and to the limited design work done up to that time. Following that, the group: (1) developed example parameters for an rf system; (2) discussed the evaluation of rf noise problems; and (3) considered the nature of feedback systems for control of both longitudinal and transverse beam excursions and instabilities. We acknowledge valuable discussions paricularly with members of the stability group

[en] This note describes a reversible dispersion matching system with arbitrary phase advance per cell. Reversible means that the match is independent of the sign of the quadrupoles. The method includes several well-known missing-magnet and reduced-magnet schemes as special cases

[en] During the workshop, two estimates of the random sextupole components in the SSC dipoles have been presented, one from Berkeley and the other from Brookhaven. In the CERN SPS, beam studies on the anti p lifetime have been performed with p and anti p bunches separated by means of electrostatic separators. We may conclude that, if the beam-beam interaction is comparable in the SPS and SSC (that is, linear tune shift = .003/interaction, total 0.2), the SSC at 20 TeV with the Berkeley sextupole errors seem safe. The Brookhaven sextupole errors may be on the borderline

[en] Two approximations are made, one essential and the other not so essential but convenient to keep the analytical treatment manageable: (1) only one nonlinear resonance is considered at a time so that the treatment is best suited when the tune is close to one resonance only. To improve this approximation, one must go to the next order which involves a canonical transformation of dynamical variables. Analytical treatment of more than one resonance is not possible for general cases; (2) in the formalism using the action-angle variables, the Hamiltonian can have terms which are independent of the angle variables. These terms are called ''phase-independent terms'' or ''shear terms.'' The tune is then a function of the oscillation amplitudes