The new muon (g−2) experiment at Brookhaven

Abstract

A new measurement of the muon anomalous magnetic moment (BNL E821) aims to obtain a factor of 20 in precision over the previous CERN measurement which had an accuracy of 7.3ppm. This increase in precision will provide a sensitivity to virtual particles into the TeV mass range and opens a substantial window for the discovery of new physics beyond the standard model. The CERN measurements established the muon as a point-like lepton obeying QED with additional corrections from virtual pions. It also provided constraints on the virtual production of new particles with masses on the order of tens of GeV. By increasing the precision of this measurement by a factor of 20, the experiment will be sensitive to the single-loop radiative contribution from the W and Z bosons with an experimental error ∼ 20% of the magnitude of the effect predicted by the standard model. In addition to experimentally testing electroweak renormalization, this measurement will be sensitive to the presence of “new physics” such as muon substructure to several TeV, supersymmetric particles, an anomalous W-boson magnetic moment, aCP violating muon electric dipole moment, and other physics beyond the standard model. In several cases, the sensitivity of E821 goes well beyond that which will be available at Fermilab, LEPII or the SSC. The construction and preparation of the precision storage ring has begun at Brookhaven. Storage ring completion is anticipated in 1993 and data collection will commence in late 1994.