SORTING STRATEGIES FOR NONLOCAL COMPENSATION OF NONLINEAR ERRORS IN LARGE HADRON COLLIDERS

The problem of sorting the random non-linear errors to improve the dyn amic aperture of a magnetic lattice is considered. We analyse the CERN Super-Proton-Synchrotron whose eight strong extraction sextupoles can be independently powered to simulate random errors. The sorting strat egy based on analytical quality factors derived through one-turn maps and normal forms is applied. This approach is proven to be well suited for non-local compensation. The analysis of the whole configuration s pace of the possible permutations shows that the analytical solution i s very close to be optimal. Good configurations are shown to be rather abundant and simulated annealing techniques do not significantly impr ove the solution. The effectiveness of the ordering procedure is verif ied for long-term six-dimensional motion and different working points.