Die Zählung von Pm-147 mit Hilfe eines Flüssig- Szintillationsdetektors unter Anwendung der Kanalverhältnismethode zur Korrektur von Löscheffekten

A method for the stabilization of liquid scintillation solutions by addition of tri-n-octylphosphinoxide, which had originally been developed for solutions containing actinide elements has been successfully applied to the counting of Pm-147 samples containing a high concentration of non-active salts and non-volatile organic substances. The channel-ratio method was used for the correction ofquenching effects. The correction curves for the quenching effects due to water, nitric acid, lithium nitrate, trilaurylamine, and tri-n-octylphosphinoxide proved to be identical within 1 to 2 %. Experiments to investigate the stability of the counting results with time gave values constant to within better than 1 % over a period of 30 days, when up to 1 volume % of 7 n HNO$_{3}$ was added to the scintillator solution. The method of stabilization described should be applicable to other nuclides of the rare earth series as well