A new method is described for radioanalysis by alpha counting of the radium content of natural and drinking water. A series of different specific chemical separations permits the isolation of radium from those impurities usually carried down by the BaSO4-RaSO4 complex. The precipitate finally obtained is thoroughly mixed with ZnS(Ag). A photomultiplier tube is used for the counting. The method is independent of the number of SO4 ions present. It is possible to operate with thin layer samples in order to obtain a better efficiency. A particular electronic device which required special attention is described. For routine work, efficiency of 52 per cent was obtained. The background can be reduced to 0.4 counts/min, and concentrations of radium as low as 10-16-10-17 c/ml can be detected. A critical study of the decay and of the increase of the alpha activity indicates the relative abundance of Ra226, Ra223 and Ra224.
©1963Health Physics Society