The ratio of the nuclear magnetic moments of ${\mathrm{He}}^3$ and ${\mathrm{H}}^1$ has been measured by NMR techniques using a gaseous sample. The result is $-\frac{{\mu }_{{\mathrm{He}}^3}\left(\mathrm{He}\right)}{{\mu }_p\left({\mathrm{H}}_2\right)}=0.76178685\mathrm{}$ (±0.1 ppm), uncorrected for magnetic shielding in He and ${\mathrm{H}}_2$, and with these shielding corrections, $-\frac{{\mu }_{{\mathrm{He}}^3}}{{\mu }_p}=0.76181237\mathrm{}\pm 0.6$ ppm. With this new value for the magnetic moment ratio the hfs anomaly is found to be ${\delta }_{{\mathrm{He}}^3}=+(217\mathrm{}\pm 3)\times {10}^{-6\mathrm{}}$. By comparison with the theory for ${\delta }_{{\mathrm{He}}^3}$ the contribution of exchange currents to ${\delta }_{{\mathrm{He}}^3}$ is calculated to be +(15±15)×${10}^{-6\mathrm{}}$.

• Received 2 January 1969

DOI:https://doi.org/10.1103/PhysRev.185.1251