The two Tesla superconducting solenoid for the Fermilab DO detector

Procurement has been initiated for a thin 2 Tesla superconducting magnet for the upgrade tracking system for the DO detector at the Fermilab Tevatron. The magnet is 2.75 long, 1.2 m diameter, and stores 5.6 MJoules magnetic energy. Among the many detailed technical specifications prepared for the magnet were those pertaining to the cold mass support system. Some issues that affected the specifications of the cold mass support system for the magnet were those of magnet alignment, and system safety in the event of an unexpected electrical short in the coil. Considerations of closed-orbit distortions in the Fermilab Tevatron yield limits on the precision with which the magnet must be aligned with the machine; the worst case occurs at beam injection and we show that the limits do not impose severe design constraints on the magnet cold mass support system. Considerations of multiple scattering and momentum resolution of the tracking system yield limits on the precision with which the tracking system must be aligned with the magnet; from realistic estimates of the resolution expected from the tracking devices we find that the magnet alignment required also imposes modest constraints on the magnet cold mass support system. Considerations of the relationship between the magnet coil and the iron yoke of the DO muon system made it possible to characterize the worst-case loadings to be expected in the event of an unexpected electrical short in the magnet. We show that it is reasonable to require that the cold mass support system be designed to support such an accident.<
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