Abstract
The possibility of applying gamma ray analysis to approximately 50 mg samples of monazite has been investigated. Three ranges of low energy gamma radiation, under 0.3 MeV, were counted with a Gamma Scintillation Spectrometer.
This extremely simple method led to very good results with samples containing only one radioactive component. With monazites containing uranium as well as thorium, the latter component being in excess, results were also good. For uranium contents that were only a few tenths of a per cent, the results did not attain the precision of chemical analysis.
In a leached mineral where the simultaneous contents of uranium, radium in excess and thorium had to be determined, the method failed, due to the smallness of the contribution of UX in the emitted radiation with respect to that of the radium family. In this case we were able to calculate an approximate value for the thorium content and make a rough estimate of the total radium content of the mineral.
With this spectrometer the use of longer counting times gives only a slight improvement in the precision of the counts. The use of somewhat larger samples will however diminish the important background fraction in the low activity countings and hence it will give a corresponding increase in the reliability of the results.