Optics and field error compensation in the FNAL permanent magnet 8.9 GeV/c proton transfer line

Protons are transported 760 m from the Booster extraction point to injection into the Fermilab Main Injector. Apart from two, comparatively short, specialized optical matching sections the transfer lattice is described by 90° betatron phase advance arc cells and missing-dipole dispersion suppressing cells. This repetitive structure, combined with the small average bend per cell makes it feasible to construct this section exclusively from low-field permanent dipoles and gradient magnets. The permanent magnet section is nearly devoid of powered correctors: trajectory control and momentum error compensation is accomplished instead by moving select gradient magnets transversely. Permanent magnets are being used in the transfer line primarily to acquire the manufacturing and operational experience necessary to ensure success of the future FNAL Recycler Ring