The ironless Costheta magnet option for the SSC

The Fermilab design of a 5 T, 5 cm aperture superconducting dipole is described, that attempts to integrate essential cryogenic details with a low cold mass, low heat leak magnet containing a coil surrounded by aluminum collars. Operating characteristics of coils made with aluminum collars are presented along with harmonic data obtained from 1 meter long 5 cm aperture collard coils. A summary of results obtained from cold tests of a 7.6 cm aperture, 6 m long aluminum collared coil in an iron vacuum vessel cryostat are reviewed. Results from the measurement of heat leak to 4.5K, 10K, and 80K are discussed for a 12 m prototype cryostat. Calculations are summarized for passively correcting the persistent current sextupole fields