Multipole compensation of long-range beam-beam interactions with minimization of nonlinearities in Poincaré maps of a storage-ring collider.

In cases of multibunch operation in storage-ring colliders, serious long-range beam-beam effects could be due to many parasitic collisions that are localized inside interaction regions or/and distributed around the ring. To reduce the long-range beam-beam effects, the compensation of long-range beam-beam interaction with magnetic multipole correctors based on minimizations of nonlinearities in one-turn or sectional maps of a collider has been proposed. With Large Hadron Collider as a test model, the effectiveness of the multipole compensation of long-range beam-beam interactions was studied in terms of improvement of dynamic aperture and reduction of emittance growth. The emittance growth was studied with a self-consistent beam-beam simulation. The study showed that both the local and global compensation of long-range beam-beam interactions with magnetic multipole correctors are very effective in increasing the dynamic aperture and improving the linearity of the phase-space region relevant to the beams.