The Brookhaven muon storage ring magnet

The muon g-2 experiment at Brookhaven National Laboratory has the goal of determining the muon anomalous g-value a(mu) ( = (g - 2)/2) to the very high precision of 0.35 parts per million and thus requires a storage ring magnet with great stability and homogeniety. A superferric storage ring with a radius of 7.11 m and a magnetic field of 1.45 T has been constructed in which the field quality is largely determined by the iron, and the excitation is provided by superconducting coils operating at a current of 5200 A. The storage ring has been constructed with maximum attention to azimuthal symmetry and to tight mechanical tolerances and with many features to allow obtaining a homogenous magnetic field. The fabrication of the storage ring, its cryogenics and quench protection systems, and its initial testing and operation are described. (C) 2001 Elsevier Science B.V. All rights reserved.