An inference of high atom densities in solid tritium for nuclear magnetic resonance measurements

At fixed temperature the ortho concentration in solid ${\mathrm{T}}_2$, as monitored by NMR, is found to decay exponentially in time with a time constant that has a minimum at 11.4 K. At 11.4 K the ortho to para conversion in ${\mathrm{T}}_2$ is 200 times larger than in ${\mathrm{H}}_2$. This enhanced conversion rate is attributed to diffusing atoms created by the tritium β decay. A hopping model is used to infer the atom number density and hopping frequency as functions of the temperature.