Determination of the production rate of low intensity isomeric transitions

Abstract

Flat 2π and cylindrical 4π multiwire proportional counters were built for counting low energy internal conversion electrons from the nuclear isomers 83mKr, 103mRh and 189mOs, induced by irradiation with high intensity 60Co and 4 MeV bremsstrahlung sources. The β-decay of 176mLu was recorded by a plastic scinillator. In this way higher sensitivities were attained than by detecting γ-rays or characteristic X-rays associated with the isomeric transitions, and the excitation of 189mOs by low energy 137Cs and 300 kV X-ray sources also became detectable. Comparatively large isomeric activities produced by linac irradiation were standardized by a Ge spectrometer for calibrating proportional and scintillation counting.