Determination of disintegration rates and γ-ray emission probabilities of 65Zn and 241Am

Radioactive solutions of 65Zn and 241Am were standardized within the frame of the CCRI (II)/BIPM key comparisons carried out recently in 2003. The activity concentrations (in Bq g−1) were determined using the 4π(proportional counter)-γ coincidence counting method with efficiency extrapolation. Liquid scintillation methods were also used for 241Am activity determination. The 1115.5 keV of 65Zn and the 26.35 and 59.54 keV of 241Am γ-ray emission probabilities were determined as 0.4971, 0.0206 and 0.3587, respectively, using a planar germanium detector. The associated relative uncertainties were 0.33%, 1.56% and 0.47%, respectively.