Activity standardisation of 223Ra

Youcef Nedjadi; Laurent Desorgher; Frédéric Juget; Thierry Buchillier; François Bochud; Claude Bailat

doi:10.1016/j.apradiso.2021.109788

Activity standardisation of ²²³Ra

Appl Radiat Isot. 2021 Aug:174:109788. doi: 10.1016/j.apradiso.2021.109788. Epub 2021 May 24.

Authors

Youcef Nedjadi¹, Laurent Desorgher², Frédéric Juget², Thierry Buchillier², François Bochud², Claude Bailat²

Affiliations

¹ Institut de Radiophysique, Lausanne, Switzerland. Electronic address: youcef.nedjadi@chuv.ch.
² Institut de Radiophysique, Lausanne, Switzerland.

PMID: 34051527
DOI: 10.1016/j.apradiso.2021.109788

Abstract

We report here on the primary activity standardisation of a²²³Ra dichloride solution in equilibrium with its decay daughters. Both the triple-to-double-coincidence-ratio (TDCR) method with an in-house TDCR detector and the CIEMAT-NIST efficiency tracing (CNET) technique with a commercial counter were used. The liquid scintillation efficiencies for both methods are about 6 while the activities they predict with about 0.4% relative standard uncertainty agree within 0.15%. For backup, the solution was also standardised with 4πγ NaI(Tl) integral counting with a well-type NaI(Tl) detector, and efficiencies computed by Monte Carlo simulations using the GEANT code. This simple technique, unused previously for this nuclide, yielded an activity concentration compatible with, but 1% lower than, the one determined by liquid scintillation counting.

Keywords: (223)Ra; 4πγ counting; Activity standardisation; CNET; Liquid scintillation; TDCR.