On 10Be standards and the half-life of 10Be

Using accelerator mass spectrometry, we have made absolute measurements of the ratios of 10Be to 9Be in the National Institute of Standards and Technology (NIST) standard reference material SRM 4325, and in material produced by ICN. We obtain for SRM 4325 a value that is 14% higher than that claimed by the NIST (30.6 ± 1.4 × 10−12 instead of 26.8 ± 1.4 × 10−12, 2σ uncertainty). Our absolute values for the ratios of 10Be to 9Be, and the activity measurements of the NIST and ICN, yield values for the half-life of 10Be of 1.53 ± 5% and 1.48 ± 5% Ma, respectively.