Standardization of 166mHo and 243Am/239Np by live-timed anti-coincidence counting with extending dead time

► The primary standardization of 166mHo and 243Am/243Np was done. ► The method used was the live-timed 4πβ(LSC)-γ(ΝaI(Tl)) anticoincidence counting. ► The small uncertainties obtained stimulate the use of the applied method. ► The first steps in order to transform 243Am in a standard were done.