Helium-isotope mass-spectrometric method for studying tritium beta decay (idea, experiment, nuclear and molecular physics applications)

Experimental data on the variation of tritium nucleus beta decay constant caused by the interaction of the resulting beta-electron with orbital electrons and shell vacancies are reviewed for free atomic tritium and molecular tritium and used to obtain the half-life of atomic tritium (T_1/2)_a=(12.264±0.018) y, the half-life of the free triton (T_1/2)_t=(12.238±0.020) y, the axial-vector-to-vector weak-interaction coupling constant ratio (G_A/G_V)_t=–1.2646 ± 0.0035 for beta decay of the triton, and an independent estimate of the free neutron lifetime τ_n= (890.3 ± 3.9_stat ± 1.4_syst) s.