Establishment of a Tolerance Budget for the Advanced Photon Source Storage Ring*

The limitations on the dynamic aperture of the Advanced Photon Source storage ring due to magnet misalignments and fabrication errors are presented. The reduction of the dynamic aperture is analyzed first for each enor considered individually, and then for combined ettor multipole fields in dipole, quadru-pole, and scxtupole magnets, excluding and including magnet misalignments. Since misalignments of the strong quadrupoles in the ring induce large orbit distortions, the effects on the dy-naraic aperture are investigated before and after orbit correc-tion. Effects of off-momentum particles and the tune depen-dence with momentum are also presented. This extensive analysis leads to the establishment of a tolerance budget. With all the errors set at the tolerance level, and with the orbit distor-tions corrected, the dynamic aperture reduction is no greater than 50 % of that of the ideal machine. I