Practical correction method for impurities on activity measurements using isotope calibrators

Radioactive impurities might cause significant error in the activity determination of a target nuclide using ionization chambers. In the present study, an impurity correction technique for 201Tl sources was performed by applying two different responses of an IG12A20 and IG11N20 ionization chamber. This technique can be extended to another method in which an attenuation filter made of tin was used to obtain different responses of an argon filled IG12A20. The results obtained with these techniques were very consistent with each other and with the reference value within their uncertainty after making the impurity correction. Examples of 64Cu activity determination were also shown.