Alignment of the high beta magnets in the RHIC interaction regions

The betatron functions inside the triplet quadrupoles in the Relativistic Heavy Ion Collider-RHIC are of the order of 1500 m, necessitating additional attention in the alignment procedure. On each side of the interaction regions eight cryogenic elements (six quadrupoles and two horizontal bending dipoles) are placed inside large cryostats. The quadrupole magnetic centers are obtained by “antenna” measurements with an accuracy of ±60 μm. The signals from the “antenna” were cross calibrated with the colloidal cell measurements of the same magnet. The positions of the fiducials are related to the magnet centers during the “antenna” measurements. Elements are positioned warm inside the cryostats, with offsets to account for shrinkage during the cool down. The supports at the middle of the two central quadrupoles are fixed, while every other element slides longitudinally inside the cryostat during cool down or warm up