Reduction of Sextupole Distortion by Shuffling Magnets in Small Groups

A method is given for reducing the most troublesome sextupole harmonics in a ring by measuring the sextupole field in groups of magnets, and ordering them according to a predetermined prescription. The predicted result is a decrease in sextupole related distortions by a factor [2/(J + 1)]¿ where J magnets, covering one or more betatron periods, are measured at one time. Simulations performed for typical SSC lattices confirm the expected improvements.