A liquid-scintillation-based primary standardization of 210Pb

Abstract

A new radioactivity solution standard of 210Pb has been developed and will be disseminated by the National Institute of Standards and Technology (NIST) as standard reference material (SRM) 4337. This new 210Pb solution standard is contained in a 5 mL flame-sealed borosilicate glass ampoule, consists of (5.133±0.002) g of a nominal 1 mol L −1 nitric acid solution, has a density of (1.028±0.002) g mL −1 at 20 °C, has carrier ion concentrations of about 11 μg Pb 2+ and 21 μg Bi 3+ per gram of solution, and is certified to contain a massic activity (9.037±0.22) kBq g −1 as of the reference time 1200 EST, 15 June 2006. All of the uncertainties cited above correspond to standard uncertainties multiplied by a coverage factor k=2. The standardization for the 210Pb content of the solution was based on 4 παβ liquid scintillation (LS) measurements using CIEMAT/NIST 3H-standard efficiency tracing (CNET). Confirmatory determinations were also performed by high-resolution HPGe γ-ray spectrometry, by 2 πα spectrometry with a Si surface barrier detector of separated 210Po, and by 4 πβ(LS)– γ(NaI) anticoincidence counting.