The chromaticity correction system, including the nonlinear correction, for the Relativistic Heavy Ion Collider (RHIC) is presented. Expected multipoles in the superconducting magnets have shown that the octupole and decapole might be large enough to reduce the momentum aperture and introduce undesirable nonlinear chromatic behavior of the machine. Simulations of these conditions have been performed with the accelerator physics tracking code TEAPOT. The chromatic dependence curves were obtained by the least square fitting. A correction to the first and the second order terms were applied by using two sextupole and two octupole circuits. The decapole correction system has been applied to correct for the third order dependence on momentum. The long term tracking studies at injection did not include the decapole correction. The studies showed that the octupole correction system significantly improves the dynamical aperture at the injection. The decapole system would not be necessary at commissioning of the machine but the correction magnets will be available. At the top energy, as to be expected, the low beta quadrupoles are the dominant source of the nonlinear momentum dependence.
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