A Computer Simulation Study of e+ e- Storage Ring Performance as a Function of Sextupole Distribution

Operational experience at CESR has shown that sextupoles are important factors in the observed beam-beam behavior. A computer program to simulate colliding beam dynamics in e+ e- Storage rings has been written. The first version of the program which does not incorporate sextupoles shows some of the characteristics measured in various machines in the past. The focus or the present work is the understanding of the effects of sextupoles on these results. To do this thin sextupoles are added in two ways. The first employs a linear-transfer/nonlinearkick algorithm for each lattice cell. The second method is to create a symplectic second-order transfer map for the entire machine. While the first method is exact, it is slow for machine lattices with many sextupoles. The luminosities, beam sizes, and tune shifts from these programs are compared. In addition, the shapes of the time-averaged transverse distributions are studied.