Evidence for revision of the evaluated half-life of 207 Bi.

The National Institute of Standards and Technology (NIST) compared the measured full-energy peak efficiency obtained from a large set of sources to that of a 207 Bi source obtained using three different half-life values. The values of the half-life used for this comparison are published in the Decay Data Evaluation Project (32.9 ± 1.4) years and the Evaluated Nuclear Structure Data File (31.55 ± 0.04) years, and in a recent NIST publication (31.20 ± 0.05) years (or (11395 ± 18) days).