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 {ital 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.