Spin relaxation of hydrogen-atom isotopes via electron spin exchange with paramagnetic gases

The mathematical form of the observables for spin relaxation of hydrogen-atom isotopes by electron spin exchange with unpolarized paramagnetic dopant gases is presented using a Boltzmann-equation approach. Hydrogen-maser, muon-spin-rotation, and stored atomic beam experiments are considered. Depending on the experimental technique, different relaxation rates are experimentally observed, but these are all related to the same intrinsic collision rate. In particular, for an unpolarized dopant, all relaxation rates are proportional to the same spin-flip cross section, and all H-atom experimental results appear to be consistent with each other, contrary to past statements in the literature