Lattice and Aperture Considerations in the Cold Magnet Synchrotron (CMS)

With either superconducting or cold aluminum coils the optimum design of bending magnets for a synchrotron tends to have approximately equal horizontal and vertical apertures. It is therefore advantageous to tailor the lattice and beam parameters so that horizontal and vertical requirements are equal; this imposes the severest constraints on the horizontal aperture, and the vertical tune vz may be allowed to be less than vx. A lattice has been designed with 48 focusing periods, six magnet superperiods each containing an 8-m straight section, vz = 7-1/ 3, vx = 10.45. This choice avoids low-order superperiod resonances and facilitates resonant vertical beam extraction. With 30-GeV injection from the AGS, a gross semiaperture of 20 mm accommodates all requirements, provided field error corrections are obtained from beam position measurements.