Direct determination of the half-life of 187Re

We have determined the beta-decay half-life of 187Re to be (4.23 ± 0.13) · 1010 y, stated at the 95% confidence level. The method consisted of separating the daughter 187Os atoms from large sources of initially osmium-free rhenium. Yields were measured by the isotope dilution method using inductively coupled plasma mass spectrometry. Precision was gained through the use of two independent spike isotopes on each of five separate, large sources of...