Chromaticity correction for the SSC collider rings

We address the issue of correcting higher order chromaticities of the collider with one or more low /spl beta/ insertions. The chromaticity contributed by the interaction regions (IRs) depends crucially on the maximum value of /spl beta/ in the two IRs in a cluster, the phase advance between adjacent interaction points (IPs), and the choice of global tune. We propose a correction scheme in which the linear chromaticity is corrected by a global distribution of sextupoles and the second order chromaticity of each IR is corrected by a more local set of sextupoles. Compared to the case where only the linear chromaticity is corrected, this configuration increases the momentum aperture more than three times and also reduces the /spl beta/ heat by this factor. With this scheme, the tune can be chosen to satisfy other constraints and the two IRs in a cluster can be operated independently at different luminosities without affecting the chromatic properties of the ring.<
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