Studies of PACMAN effects in the HL-LHC

This note summarises the status of the studies on PACMAN beam-beam effects in the HL-LHC project. It is shown that the orbit, tune and chromaticity effects due to head-on and long-range beam-beam interactions are tolerable without dedicated mitigations in the nominal scenario. Nevertheless, the orbit effects are not negligible when considering the tolerance for the asynchronous beam dump. Thus, an adjustment of the required apertures is suggested. The luminosity loss due to the PACMAN orbit effects is shown to be negligible in the high luminosity experiments and tolerable in the low luminosity ones. The single particle stability is also briefly discussed, showing that it would be interesting to perform further studies on dynamic aperture taking into account the offsets at the IPs induced by orbit effects due to the strong chromaticity introduced in the presence of residual dispersion at the interaction point. The concept of PACMAN linear coupling is introduced and implemented in the code TRAIN. This effects imposes tight tolerance on the alignment of the crossing angles, thus a procedure for experimental validation at the LHC is proposed.