A 20 T hybrid solenoid for the collection of pions for a muon collider

In order to generate intense muon beams for a muon collider, intense pion beams must be produced in a stationary proton beam target. The pions produced by the target must be captured before they can go through phase rotation and decay into muons. A 20 T solenoid with a clear bore of 150 mm can capture particles with a transverse momentum of 225 MeV/c or less. As the captured particles leave the capture solenoid, the magnetic induction is decreased to 5 T while the beam pipe diameter increases to 300 mm. Phase rotation of the pions and the decay of the pions to muons will occur at 5 T. The capture solenoid and the solenoids just downstream from the capture solenoid are subject to high heat loads (up to 4.8 MW) and radiation loads from the target. The conventional inner solenoid of the 20 T hybrid magnet system and the water cooled absorber will absorb virtually all of the particle energy from the target thus protecting the superconducting part of the solenoid system from excessive radiation heating. This report also describes the solenoid magnets from the capture zone to the solenoidal beam channel within the phase rotation RF cavities.