The Magnetic Moment of the Helium Atom in the Metastable Triplet State

The atomic beam magnetic resonance method has been used to measure the ratio of the $g$ value of the two-electron system in helium in the metastable $1s2s$, ${}_{}{}^3{}_{}{}^{}S_1^{}{}_{}{}^{}$ state to the $g$ value of the one-electron system in atomic hydrogen in the ground $1s$, ${}_{}{}^2{}_{}{}^{}S_{\frac{1}{2}}^{}{}_{}{}^{}$ state. The metastable helium and the atomic hydrogen were alternately produced in a dc discharge tube. The helium beam was detected by measurement of the current of electrons ejected when the metastable atoms strike a wolfram wire. The hydrogen beam was detected by a Pirani gauge.