Modular optical design of the LHC experimental insertions

To optimize the use of space, the LHC insertions combine dispersion matching (arc and ring separation/recombination), beam focalization at the interaction point and betatron phase advance control within a unique optical module. In this paper, we show that the significant dispersion produced by the separation/recombination dipoles can be treated separately, allowing a separation of the optical functions in the insertion. This methodology yields the flexibility and robustness needed to adapt the insertion to a lattice with a variable tune split.