Standardization of 110mAg and 75Se by the beta-efficiency extrapolation method

The complex beta–gamma emitter 110mAg and the electron-capture radionuclide 75Se were standardized, using the “beta-efficiency extrapolation method”. The coincidence equipment was a NE modular type. The detectors were a NaI (Tl) counter and a 4π proportional counter. For 110mAg, one tried to fulfil the “linearity conditions”. For 75Se one tried to minimize errors arising from an isomeric state and strong internal conversion; an “equivalent scheme” was used. Combined uncertainties of ≈1% were obtained.