Adaptation of PTB’s analytical modelling for TDCR–Cherenkov activity measurements at LNHB

Designed for triple to double coincidence ratio measurements based on liquid scintillation, the three-photomultipliers detection system can also be applied for Cherenkov counting using aqueous solutions. For activity determination, a specific modelling of Cherenkov light emission has to be constructed. For that purpose, the analytical modelling first developed at PTB was adapted to account for the physical features of the detection system used at LNHB. The first results are presented in the case of activity measurements of two high-energy β^?-emitters (⁹⁰Y and ⁸⁹Sr). The analytical modelling was also tested for the standardization of ⁶⁸Ge in a solution of ⁶⁸Ge/⁶⁸Ga in equilibrium in the framework of a BIPM international comparison in 2014.