First results from the new muon (g-2) experiment

A new and improved experiment for measuring the muon magnetic anomaly at the Brookhaven National Laboratory (BNL) was successfully started and has yielded first results. New major components of the experiment include a superferric storage ring, a superconducting inflector, electrostatic quadrupoles, lead-scintillating fiber electron calorimeters and a high precision NMR magnetic field measurement and control system. The first measurement of the ratio R of the spin precession frequency of the positive muon relative to that of a free proton gives R=(3.707 219±0.000 048)×10−3. It is similar in accuracy and in good agreement with previous CERN measurements for μ+ and μ−. A muon kicker has been installed to boost the number of stored particles in the storage ring magnet and was successfully commissioned recently. The data acquired so far is expected to lower significantly the uncertainty in R. First extensive data-taking will start soon.