Direct determination of half-life of 214Pb by gamma spectrometry and comparison with previous indirect measurements

A new value of half-life of 214Pb was determined using 214Pb-enriched radioactive sources made of polyurethane foam filters treated with Rn-enriched water. Measurements based on cumulative gamma rays countings yielded a value of 27.06 (7) min. This result is 0.17 min longer than the most recent value measured by indirect methods reported in the scientific literature (Martz et al., 1991). The difference between these two measurements is caused by beta recoil whose effects in glass substrates had been neglected.