Standardization of 152Eu

152Eu was standardized within the frame of a BIPM international comparison. The solution was prepared and bottled by PTB. The ampoules were measured at BIPM in the SIR ionization chambers and then dispatched to the participating laboratories. In the Radionuclide Metrology Laboratory of IFIN-HH, the solution was standardized using a coincidence method with “beta–efficiency extrapolation” by foil absorption. A simple 4π beta–gamma-coincidence system was used, with NaI(Tl) and 4πPC detectors. No significant impurities were found apart for 0.5% 154Eu. To obtain linear extrapolation plots, a “gamma-window” of 180–1500 keV was chosen. Dead-times of 10 μs were used. A combined uncertainty of 0.24% was obtained, mainly from the extrapolation procedure component.