The Hyperfine Structure of Tritium

The hyperfine structure of the ground state of tritium was measured by the atomic beam magnetic resonance method. The frequency of the field independent central Zeeman component of the transition F=1↔F=0 gives the h.f.s. almost exactly with a field correction of less than 0.001 Mc. The mean of three independent determinations of the h.f.s. in different weak magnetic fields is 1516.702±{}0.010 Mc. The probable error is caused by the uncertainty in the Doppler correction and possible asymmetry in the resonance lines causing a shift in the center of the line. The reproducibility of determining the center of the resonance line was ±{}0.002 Mc. The theoretical value of the h.f.s. based on the triton-proton moment ratio and the value of the h.f.s. of hydrogen is 1516.709±{}0.015 Mc. The theoretical and experimental values agree within the probable error of the moment ratio, 1 part in 10⁵, which also proves that the spin of the triton is {}.