Magnetic Resonance Studies of Gaseous Atomic Hydrogen at Low Temperatures

Magnetic resonance studies are reported for a low-density gas of hydrogen atoms for $4.2<T<\mathrm{}77\mathrm{}$ K. The resonance observed is between the two lowest hyperfine levels in a field of 6.5 kG, where this splitting has its minimum value (765 MHz). Information is obtained about translational diffusion through ${\mathrm{He}}^4$ and ${\mathrm{H}}_2$ buffer gases, frequency shifts and broadening due to wall collisions, and the effects of spin-exchange broadening.