Permanent gradient magnets for the 8 GeV transfer line at FNAL

The 8 GeV transfer line feeding protons into the new Fermilab Main Injector has been built using strontium ferrite permanent magnets. This article addresses the design and manufacture of the 67 combined function magnets; permanent horizontal and vertical bend dipoles and quadrupoles were also built. The combined function magnets were built with a mean integrated strength at midaperture of 0.56953 T-m (central field nominally 0.15 T), and a gradient of 3.23% per cm relative to the dipole strength (nominal gradient=0.48 T/m). Thermal compensation of these bricks was effected by use of a nickel-iron alloy. The magnets were thermally cycled from 20°C to 0°C to condition the ferrite against irreversible thermal losses; the compensation was measured with a flipcoil and verified with a rotating harmonics coil. We present details of the magnet assembly process and also summarize the magnetic measurements