A note on the half-life of 209Po

The widely adopted value of (102±5) a for the 209Po half-life, which is based on a single determination reported in 1956, appears to be in error by a large factor. Decay data from two separate primary standardizations of a 209Po solution standard, conducted approximately 12 years apart, are inconsistent with the adopted value and its assigned uncertainty. An estimated half-life, larger than the adopted value by about 25%, is more consistent with the standardization data. A longer half-life is also supported by measurements on a recently standardized 210Pb solution standard.