A new measurement of the positive muon's anomalous magnetic moment has been made at the Brookhaven Alternating Gradient Synchrotron using the direct injection of polarized muons into the superferric storage ring. The angular frequency difference omega_{a} between the angular spin precession frequency omega_{s} and the angular orbital frequency omega_{c} is measured as well as the free proton NMR frequency omega_{p}. These determine R = omega_{a} / omega_{p} = 3.707~201(19) times 10^{-3}. With mu_{mu} / mu_{p} = 3.183~345~39(10) this gives a_{mu^+} = 11~659~191(59) times 10^{-10} (pm 5 ppm), in good agreement with the previous CERN and BNL measurements for mu^+ and mu^-, and with the standard model prediction.
The anomalous g value is related to the gyromagnetic ratio by MOM(NAME=ANOMALOUS MAGNETIC) = (G-2)/2. The beam momentum spread is about 1 PCT.
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, ωa, between the spin precession and orbital frequencies was determined by measuring the time distribution of high-energy decay positrons. The ratio R of ωa to the Larmor precession frequency of free protons, ωp, in the storage-ring magnetic field was measured. We find R=3.707220(48)×10−3. With μμ/μp=3.18334547(47) this gives aμ+=1165925(15)×10−9 ( ±13ppm), in good agreement with the previous CERN measurements for μ+ and μ− and of approximately the same precision.
The anomalous g value is related to the gyromagnetic ratio by MOM(NAME=ANOMALOUS MAGNETIC) = (G-2)/2. The beam momentum spread is about 1 PCT.
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