¹⁰⁹Pd and ¹⁰⁹Cd activity standardization and decay data

Two basic measurement techniques were used to establish the activity of solutions of ¹⁰⁹Cd. In one, the activity was derived from the sum of conversion-electron and γ-ray emission rates from the 88.034-keV state of ^109mAg through which all decays pass. Conversion electrons were measured by both a liquid-scintillation counter and a 4π Si(Li) spectrometer. Gamma rays were measured with a NaI(Tl) well crystal with a high and calculable efficiency. In the other method, liquid-scintillation counting was used to measure the activity of the analogue β-particle-emitting radionuclide ¹⁰⁹Pd to ±0.41%, and γ-ray spectrometers were used to compare the emission rates from quantitative samples of ¹⁰⁹Pd and ¹⁰⁹Cd. The half life of ¹⁰⁹Pd was measured as (13.404 ± 0.008) h, in agreement with an earlier result. For the 88.034-keV transition of ^109mAg, a total internal-conversion coefficient of 26.21 ± 0.14 and a γ-ray emission probability of (3.675 ± 0.018)% were deduced.