A rapid low-background assay of ²¹⁰Pb in archaeological lead

In this work, we present a fast and highly efficient method for the measurement of ²¹⁰ 210 Pb in metallic archaeological lead using the commercial low-background liquid scintillation counter Wallac Quantulus 1220 installed at the University of Milano–Bicocca (Italy). By combining an optimized chemical preparation with pulse-shape analysis (PSA), the technique achieves sensitivities at the level of a few 10² 10 2 mBq/kg within one week of measurement, using sample masses below 1 g. The method enables the simultaneous identification of the β β decays of ²¹⁰ 210 Pb and ²¹⁰ 210 Bi and the α α decay of ²¹⁰ 210 Po, allowing a direct verification of secular equilibrium within the decay chain. With extended acquisition times, detection limits below 100 mBq/kg are reached after approximately 40 days. This approach provides a rapid, accessible, and reliable tool for the radiopurity screening of lead, and is well suited for quality control and R&D activities in next-generation low-background and rare-event physics experiments. Moreover, the method has the potential to be extended to other materials relevant for low-background applications.