Influence of self-absorption corrections in the quantification of ²¹⁰Pb and ²⁴¹Am for sediment dating

The nuclides ²¹⁰Pb and ²⁴¹Am are used in geochronological studies. In this work, we examine the influence of the sediment chemical composition on the self-attenuation corrections needed for the accurate determination of specific activities for ²¹⁰Pb and ²⁴¹Am used for sediment dating. A theoretical exercise was carried out evaluating the relative bias obtained by four different analytical laboratories in the quantification of the ²¹⁰Pb and ²⁴¹Am activity concentration by gamma-ray spectrometry. The laboratories considered the same density for the sediment sample, but each one used a different chemical composition in the Monte Carlo calculations, and six different HPGe detectors (including n and p-types). An estimate of the impact that would have the relative biases found in the estimation of the ²¹⁰Pb sediment ages, applying the Constant Rate of Supply (CRS) dating model, is also given. In addition, the performance scores that the laboratories would have obtained in a hypothetical IAEA proficiency test are also presented. - Highlights: • Inaccuracies in sediment dating can be associated to self-attenuation corrections. • Deviations in the estimation of ²¹⁰Pb sediment ages (CRS model) are presented. • The performance of laboratories in an IAEA proficiency test is evaluated.