Design study for 20 T 15 cm bore hybrid magnet with radiation-resistant insert for pion capture

To capture pions the Neutrino Factory and Muon Collider Collaboration needs a field of ~20 T throughout a cylinder 15 cm in diameter and 60 cm long, falling over the next 18 m to 1.25 T, while the bore increases fourfold inversely as the square root of the field. We propose a hybrid system. The superconducting magnet is of world-class parameters, storing 600 MJ and including a coil to generate 14 T in a bore of ~1.3 m. Intercoil forces reach 100 MN. For high radiation resistance, the insert coil is of mineral-insulated hollow conductor, as developed for the Japan Hadron Facility; it would require 12 MW to generate 6 T. Needed is research to develop a more efficient hollow conductor or radiation-resistant insulator for a Bitter coil