Measurement of the Pb-211 half-life using recoil atoms from Rn-219 decay.

The radioactive half-life of 211Pb was measured, by alpha-particle counting of samples of radiochemically pure 211Pb in equilibrium with its alpha-emitting progeny, 211Bi and 211Po. The samples were prepared by the collection of 215Po recoil atoms from the decay of the 219Rn decay progeny produced from a 223Ra sample onto stainless steel discs. The radioactive decay of the 211Pb was measured utilising a 2pi proportional counter operating on the alpha plateau. A half-life of 36.165 (20) min was determined, which is in agreement with currently available literature. A full uncertainty budget is presented. A recommended half-life of T1/2(211Pb) = 36.161 (21) min has been evaluated from the current literature values.