Measurement and simulation of beam-beam effects in the weak/strong regime

In an effort to gain insight into the beam-beam interaction and its effect on beam distributions, the authors explored the weak/strong colliding-beam regime both experimentally and via simulation. In machine experiments, the weak beam, because it is just a collection of test particles which do not perturb the strong beam, may be repeatedly sacrificed and replaced during the course of measurements. Diagnostic techniques which exploit this fact were developed. They made it possible to make beam-profile measurements in the core, the skirt, and the remote tails of the distribution. The authors describe these techniques and report on some beam distribution surveys performed on the Cornell Electron-Positron Storage Ring (CESR). Results of a computer simulation designed to duplicate the weak/strong measurements are also presented. Simulation results overlapping with actual machine measurements are available only in the core and near-skirt regions