MINIMIZING SELF-ABSORPTION IN 4$pi$ /cap beta/-COUNTING
MINIMIZING SELF-ABSORPTION IN 4$pi$ /cap beta/-COUNTING The incorporation of small Teflon particles into a solution of a weak BETA emitter, which is dried and 4 pi BETA -counted, was found to reduce self- absorption markedly. Sources of S/sup 35/, Pm/sup 147/, and Ni/sup 63/ were studied with and without the Teflon treatment. In the case of S/sup 35/, self- absorption can be reduced from 28 to 5.1 per cent if the mass of the source is about 0.5 mu g and 5 mu g of Teflon particles are added. Promethium-147 self- absorption can be reduced from 17 to 2.4 per cent for carrier masses of <1 mu g, and if as much as 10 mu g of carrier is present Pm/sup 147/ selfabsorption can be reduced from 54 to 4.3 per cent. Nickel63 self-absorption was reduced from 76 to 41.5 per cent but the original value of the Ni/sup 63/ standard source was not known accurately. (auth)
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