Generalized 4π(LS)β—γ tracer method for standardization of pure beta emitters

The basic mathematical relationships, as well as experimental results, are presented for a generalized tracer method, with a multiparameter coincidence and anti-coincidence system, for absolute activity measurements of pure beta-emitters. A liquid scintillation counter, with two photomultipliers working in coincidence, was used for beta-particle detection and two scintillation counters with NaI(Tl) crystals for gamma-photon detection. le extrapolation procedure has been applied: first, extrapolation as a function of tracer counting efficiency, and second, extrapolation as a function of emitter to tracer concentration ratio in the mixed radioactive solution. It should be emphasized that application of the second extrapolation procedure minimizes the counting uncertainty given by the first procedure. perimental results are illustrated by 63Ni and 147Pm activity measurements with the same tracer, 60Co. The uncertainties obtained were within a limit of 1% for a 0.99 confidence level. The radioactive solutions in question (63Ni, 147Pm) were measured afterwards by the TDCR method (triple to double coincidence ratio) and the results compared. Good agreement (within the uncertainties of both methods) was obtained.