Status of correction magnet systems in the main ring at Fermilab

For reducing the chromaticity and suppressing various resonances, several systems composed of trim quadrupoles, skew quadrupoles, regular and skew sextupoles, and octupoles are now used in the main ring. These systems make it possible to achieve the transmission in the main ring of 90 percent or better for routine operation with the intensity in excess of 1013 protons per pulse. In particular, insertion of one-inch plastic spacers in chromaticity correcting sextupoles was very effective in compensating for high-order nonlinear fields in the bending magnets. (auth)