Beta-beating and amplitude detuning from corrector misalignments in the LHC and HL-LHC

There are correctors in the insertion regions (IRs) of the LHC, known as MCX, which could be misaligned in the transversal plane by up to about 1 mm. This could cause several unwanted effects such as β-beating and changes to the amplitude detuning. The High Luminosity LHC (HL-LHC) upgrade will introduce many changes to the accelerator lattice and will depend on even lower values of β∗. The effects of MCX misalignments are therefore studied for both LHC and HL-LHC. MCS is another type of corrector designed to compensate for the b3 error of the main dipoles. It has been observed that there is an offset of the MCS with respect to the reference orbit, which causes feed-down to coupling. A previously developed model for the transversal coupling pattern along the LHC is further developed by adjusting multipole parameters. The results show that the expected MCX misalignments cause a β-beating below 1 % and a change in first order amplitude detuning of up to 2 · 104 m−1 for LHC. It is found that that the coupling pattern can be explained very well by MCS misalignments, while it is very hard to improve the agreement between model and measurements using changes in skew quadrupole strengths and s-rotations of regular quadrupoles.