New Measurement of the Anomalous Magnetic Moment of the Positive Muon

The muon anomalous magnetic moment has been measured in a new experiment at Brookhaven. Polarized muons were stored in a superferric ring, and the angular frequency difference, {omega}{sub a} , between the spin precession and orbital frequencies was determined by measuring the time distribution of high-energy decay positrons. The ratio R of {omega}{sub a} to the Larmor precession frequency of free protons, {omega}{sub p} , in the storage-ring magnetic field was measured. We find R=3.707thinsp220(48){times}10{sup {minus}3} . With {mu}{sub {mu}}/{mu}{sub p}=3.183thinsp 345thinsp47(47) this gives a{sub {mu}{sup +}}=1thinsp165thinsp 925(15){times}10{sup {minus}9} ({plus_minus}13 ppm ), in good agreement with the previous CERN measurements for {mu}{sup +} and {mu}{sup {minus}} and of approximately the same precision. {copyright} {ital 1999} {ital The American Physical Society}