Results of a measurement of the half-life of tritium by absolute counting are presented. The method consisted of the mass spectrometric analysis of a hydrogen-tritium mixture enriched in tritium, the dilution of some of this material with hydrogen in a known way to a countable level of activity, and the counting of a portion of the diluted gas in a Geiger counter of known effective volume. The half-life was found to be 12.41 with uncertainties of plus 0.15 and minus 0.25 year.

• Received 2 April 1951

DOI:https://doi.org/10.1103/PhysRev.83.537