Magnetic Moment of the Positive Muon

The magnetic moment of the positive muon has been measured relative to that of the proton by determining its precession frequency in a magnetic field measured by proton NMR. With both protons and muons bound in a spherical sample of water, the result is ω_μ^'ω_p^'=3.183362±0.000030 (9.4 ppm). Including uncertainties due to the chemical environment of the muon, the result for free muons and protons is ω_μωₚ=3.183330±0.000044 (14 ppm) which is consistent with recent measurements of the hyperfine splitting of muonium.