High field solenoids for muon cooling

ABSTRA CT The proposed cooling system for the muon collider will consist of a 200 meter long line of alternating field straight solenoids interspersed with bent solenoids.The muons are cooled in all directions using a 400 mm long section liquid hydrogen at high field .The muons are accelerated in the forward direction by about 900 mm long, 805 MHz RF cavities in a gradient field that goes from 6 T to -6 T in about 300 mm.The high field section in the channel starts out at an induction of about 2 T in the hydrogen.As the muons proceed down the cooling channel, the induction in the liquid hydrogen section increases to inductions as high as 30 T. The diameter of the liquid hydrogen section starts at 750 mm when the induction is 2 T. As the induction in the cooling section goes up, the diameter of the liquid hydrogen section decreases.When the high field induction is 30 T, the diameter of the liquid hydrogen section is about 80 mm.When the high field solenoid induction is below 8.5 T or 9T, niobium titanium coils are proposed for generating .themagnetic field .Above 8.5 T or 9 T to about 20 T, graded niobium tin and niobium titanium coils would be used at temperatures down to 1.8 K. Above 20 T, a graded bybrid magnet system is proposed, where the high field magnet section (above 20 T) is either a conventional water cooled coil section or a water cooled Bitter type coil.Two types of superconducting coils have been studied.They include; epoxy impregnated intrinsically stable coils, and cable in conduit conductor (CICC) coils with helium in the conduit.