Magnetic measurement, fiducialization and alignment of large dipoles for the MIT-Bates SHR

The South Hall Ring (SHR) lattice uses sixteen large dipoles originally designed for the Princeton-Pennsylvania Accelerator. These 3.6 m long, 30 ton dipoles have bend radii of over 9 meters and gaps of only 7.6 cm. The requirement that the four dipoles be powered in series, as well as other restrictions, resulted in magnetic and mechanical alignment tolerances which are very demanding for magnets of this size and shape. Two independent methods were used for measurement of the field integral along the design orbit. Field integrals were measured on all dipoles using a long coil excited by ramping the field. On four dipoles, the integrals were also measured using Hall probes moving along the design orbit. The techniques and results will be presented. The fiducialization of these dipoles was accomplished using precision-machined fixtures and the SLAC computer-aided Industrial Measurement System. Position corrections due to different measured effective lengths of these magnets will be discussed, and details of fiducialization and alignment will be presented