Fully experiment request driven beta* and separation luminosity levelling at the LHC

During the third run period (2022-2026) of the CERN Large Hadron Collider (LHC), as well as for the future High-Luminosity LHC era, luminosity levelling is key to control the event pile-up in the experiments as well as the heat load to the cryogenic system of the superconducting magnets close to the interaction points. During 2024 proton physics operation, a new luminosity levelling scheme was introduced for the high-luminosity experiments, ATLAS and CMS. Combining levelling by optical squeeze (beta*) with small transverse separation changes gives the beam stability benefits of beta* levelling (head-on tune spread and landau damping) while keeping the flexibility of separation levelling (independent levelling for each experiment in arbitrary steps of luminosity). This not only allowed each experiment to set their luminosity target independently, but also reduced the luminosity spread during levelling from 5%, when using just beta* levelling, to less than 3%, resulting in a more homogeneous data set.