Precise and accurate determination of the half-life of the α-decay nuclide 243Am using 241Am as the reference isotope

A re-determination of the half-life of the α-decay nuclide 243Am is reported using the relative activity method. Different synthetic mixtures were prepared by mixing solutions of isotopically pure 241Am and enriched 243Am isotopes, with 241Am/243Am α activity ratios in the range of 0.2–2. The 241Am/243Am atom ratios in these mixtures were determined by thermal ionization mass spectrometry and the α activity ratios were obtained by α spectrometry. A value of 17.022±0.027 was obtained for the half-life ratio of 243Am to that of 241Am. Using a value of 432.2±(0.15%) a for the 241Am half-life, a value of 7357±23 a (1σ) was obtained for the half-life of 243Am. This is the value with highest precision and accuracy reported so far.