R. Littauer

Beam Diagnostic Instrumentation at CESR

We discribe various beam diagnostic devices in use at CESR, an 8 GeV electron-positron storage ring operating primarily in the 4.7 to 5.5 GeV beam energy range. Getting the last 20% of performance depends to some extent on empirical tuning and appropriate presentation of various parameters is very important. Several devices are most useful in machine studies and we describe their operation. The individually regulated quadrupoles in CESR provide unique opportunities for lattice measurements and calibration of beam position monitors.

CESR status and performance

Machine performance for the running period is reviewed with an emphasis on phenomena associated with the large number of parasitic crossings peculiar to a single ring collider with multi-bunch beams.

Pulse-Height Analyzer for Neuro-Physiological Applications

A five‐channel differential pulse‐height analyzer is described, designed specifically for the observation of action potentials in nerve fibers. By measurement of the pulse amplitudes, it is possible to follow the activity of one or more single nerve fibers continuously.

An Ion Current Integrator

An electronic integrator suitable for measuring ionization currents down to 10−11 ampere is described. The instrument simultaneously displays both the instantaneous value of the current and the total charge received. Automatic recycling is achieved with the aid of a contact mounted on the movement of a standard meter. Substantial lengths of coaxial cable with standard connectors may be connected to the input without producing unduly large leakage currents or changing the calibration, so that remote operation of the integrator is feasible.

Single Bunch Current Dependent Phenomena in CESR

Single bunch current dependent phenomena have been examined in CESR, the Cornell Electron Storage Ring. These measurements are described and their results compared with predictions using the broad band resonator model of vacuum chamber impedance. A transient anti-damping effect in the vertical plane has been observed. The influence of various machine parameters on this effect will be described and a possible mechanism suggested.

Improvements to the CESR injector and injection process

It is essential that the storage-ring beam injection time be minimized at an e/sup +/e/sup -/ collider factory in order to maximize the integrated luminosity output of the facility. We describe a program of improvements to the CESR injector chain and injection process which have resulted in a reduction in the CESR fill time of /spl sim/40%. This has in turn allowed shorter high-energy-physics run lengths so that a higher average luminosity is maintained. Shorter fill times have resulted from increased linac beam intensity, stability and reliability, improved synchrotron transmission, faster machine condition switching time, improved CESR injection efficiency and a change to the CESR filling cycle in which both the positron and electron beam currents are topped up at the end of a run.

Interaction of CESR vacuum pumps with stored beam

The anomalous antidamping of some multibunch modes in the Cornell Electron Storage Ring (CESR) has been shown to depend on the distributed ion pumps being powered. The pumps also modify some other aspects of beam dynamics. These effects were observed in connection with studies of the behavior of the pumps themselves, which is affected in a complicated manner by the circulating beams. The results of some preliminary observations are reported.<<ETX>>

The CESR Control System

Computer control of CESR, the Cornell (8 + 8)GeV e+e- colliding-beam facility, places special emphasis on response speed, operator convenience, and economy of programming effort. Individual subsystem computers (PDP-11/34@) run autonomously under standard operating systems. Each has its own high-speed data bus network through which it controls accelerator components and accepts operator commands. Message traffic between computers is restricted to links which give a central DECsystem-1070 direct memory access to each of the PDP-11s. The 1070 can control higher-level operations by using slave tasks running in the PDP-11s; it also makes its resources available for data storage and manipulation, editing of program source files (mostly FORTRAN), and preprocessing by the FLECS translator.

The Multiplex Control System for the Cornell 10-GeV Synchrotron

The outlines of a time-sharing multiplex control system for the Cornell 10-GeV electron synchrotron were presented at the First National Particle Accelerator Conference, March 19651. The synchrotron is now nearing completion; injection studies involving more than half the guide-field ring were carried out in 1966. At that time, the multiplex control system was working for most of the needed parameters: we report below on the results of this operating experience. We also present an outline of the steps which are being taken to use a computer for supervision and control of many of the accelerator components.

Investigation of the Mobius accelerator at CESR

We present a status report on the investigation of the Mobius scheme for producing equal-emittance round beams at CESR. An insert has been constructed with six 45/spl deg/ rotated quadrupoles which interchange horizontal and vertical betatron oscillations on each passage. We describe the single-beam dynamics and the limitations introduced by the chromaticity correcting sextupoles. We also report on our two-beam experience.