The Anomalous Magnetic Moment of the Electron

The ratio of the electron spin $g$ value and the proton $g$ value has been measured with high precision. It is found that $\frac{g_s}{g_p}=658.2288\mathrm{}\pm 0.0006$, where $g_p$ is the $g$ value of the proton measured in a spherical sample of mineral oil. This result, when combined with the measurement by Gardner and Purcell of the ratio of the electron orbital $g$ value and the proton $g$ value, yields for the experimental value of the magnetic moment of the electron ${\mu }_s=(1.001146\mathrm{}\pm 0.000012){\mu }_0.$ The result is in excellent agreement with the theoretical value recently calculated by Karplus and Kroll: ${\mu }_s=\left(1.0011454\right)\mathrm{}{\mu }_0.$