Luminosity optimization and leveling in the Super Proton-Proton Collider

摘要

Purpose The design luminosity and the beam energy scale in the future Super Proton-Proton Collider (SPPC) are unprecedented. In this article, different luminosity and leveling scenarios are studied to see if the luminosity design goal is feasible. Methods The luminosity in a collider can be optimized by a group of machine parameters including beam emittance, number of bunches, bunch population, beta functions at the interaction point (IP), colliding mode (such as head-on or crossing, round or flat optics) and their changes during the colliding process. The beam-beam effects, event pileup and machine turnaround time have direct impact on the luminosity. Different measures or scenarios by taking the above factors are studied. When crab cavities are not available, the flat optics is studied to recover the luminosity lost due to a large crossing angle. Results The luminosity patterns during the physics run and averaged luminosities are given for different luminosity schemes. One can compare the performance potential and the technical difficulties among the schemes. The difference between the round optics and flat optics in the case of no crab cavities is presented. Conclusions SPPC has a very high performance in the averaged luminosity. Flexible luminosity optimization and leveling schemes are available to enhance the physics performance. The flat optics as a backup plan in the case of no crab cavities does help to improve the luminosity compared with the round optics.