The Brookhaven muon storage ring magnet

The muon g-2 experiment at Brookhaven National Laboratory has the goal of d etermining 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 magne t with great stability and homogeniety. A superferric storage ring with a r adius of 7.11 m and a magnetic held 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 st orage ring has been constructed with maximum attention to azimuthal symmetr y and to tight mechanical tolerances and with many features to allow obtain ing a homogenous magnetic field. The fabrication of the storage ring, its c ryogenics and quench protection systems, and its initial testing and operat ion are described. (C) 2001 Elsevier Science B.V. All rights reserved.