A new measurement of the ¹²²Sb half-life

Following significant discrepancies observed when decay-correcting ¹²²Sb γ-peak count rates to a reference time, we looked at the literature supporting the presently recommended 2.7238(2) d (1σ) ¹²²Sb half-life value as the source of these discrepancies. Investigation revealed that the value was derived from an inconsistent dataset and was published without reporting details of the experiment nor the uncertainty budget. In this work we performed a new measurement of the ¹²²Sb half-life by measuring the ¹²²Sb decay of neutron-activated antimony samples using state-of-the-art γ-detection systems characterized in terms of efficiency drift and random pulse pile-up. The measurement was carried out in two different laboratories with the same method. The resulting 2.69454(39) d and 2.69388(30) d (1σ) ¹²²Sb half-life values are in agreement at the evaluated 10-4 relative combined standard uncertainty level but are significantly lower (1.07% and 1.10% lower, respectively) than the preexisting recommended value. (author)