A muon detector system including central and end air-core superconducting toroids and muon detectors enclosing a central calorimeter/detector are described in this paper. Muon detectors are positioned outside of toroids and all muon trajectory measurements are made in a nonmagnetic environment. Internal support for each magnet structure is provided by sheets, located at frequent and regularly spaced azimuthal planes, which interconnect the structural walls of the toroidal magnets. In a preferred embodiment, the shape of the toroidal magnet volume is adjusted to provide constant resolution over a wide range of rapidity.

Disclosed is a method for producing a superconductor of the R-Ba-Cu-O system which comprises of selecting an insulating material of the formula RBa{sub x}Cu{sub y}O{sub z} where R is selected from the group consisting of Y, La, Pr, Nd, Sm, Eu, Gd, Ho, Er, Tm, and Lu, and where x ranges from about 1.7 to about 2.3, y ranges from about 2.7 to about 3.3 and z ranges from about 5.0 to about 6.99, and halogenating said material with a halogen selected from the group consisting of chlorine, bromine, iodine, and mixtures thereof, while maintaining said material at a temperature ranging from about 160 to about 440{degrees}C, for a period of time sufficient to cause incorporation of said halogen into said material. Also, disclosed are the materials produced by the method and articles of manufacture incorporating said materials as electronic circuitry components.