The Coupling Correction System at Rhic: Results for the Run 2000 and Plans for 2001*

The RHIC coupling correction system has been commissioned during the Year 2000 run, which marked the successful first year of operation of the machine. The RHIC coupling correction system is described with particular emphasis on its flexibility, which allows using both global and local coupling compensation techniques. Coupling measurements and correction data are presented for the RHIC Blue and Yellow rings, together with the procedure used to reduce the minimum tune separation to 0.001, the typical resolution for tune measurements during run 2000. We further demonstrate how local coupling compensation in the interaction regions substantially reduces the strength of the skew quadrupole families used for global coupling compensation. Figure 1: Schematic view of the skew quadrupole correction system in the RHIC Blue ring. 1 THE CORRECTION SYSTEM The RHIC coupling correction system is schematically described in Figure 1 for the Blue ring, the system for the Yellow ring being an exact copy of this. A total of 48 skew quadrupoles per ring are wired up in 3 families to allow global coupling corrections, and 12 independently powered skew quadrupoles are located in the Interaction Region (IR) triplets to allow for local correction of coupling sources in the IR’s. Every skew family includes 16 skew quadrupoles, located in regions adjacent to the IR’s; four power supplies per family power the skew quadrupoles in strings of three to five magnets. This powering scheme optimizes the logistics of power supply positioning in the ring service building and adds degrees of freedom to the system. The 4 power supplies in the family are set to the same current in software. By powering with opposite currents skew quadrupoles in the same family but opposite positions in the ring (see Figure 1), their effect adds up, given the 0-7803-7191-7/01/$10.00 ©2001 IEEE. 3212 Proceedings of the 2001 Particle Accelerator Conference, Chicago