THE EFFECT OF ACTINON AND RADON ON THE DETERMINATION OF THORON BY THE EMANATION METHOD

The problem of the influence of Ra/sup 226/and Ra/sup 223/ on Rn/sup 220/ measurements was investigated with an ionization chamber. It was found that an increase of Ra/sup 226/ and of the Ra/sup 223/ in relative equilibrium with it cause a nearly directly proportional increase in the activity recorded by the ionization chamber. No effect was noted if the Ra/sup 226/ concentration was kept below 1 x 10/sup -9/ g. An equlibrium solution containing 4 x 10/sup -8/ g Ra and a solution containing 3.52 x 10/sup -3/g Th/sup 232/ were used for the emanation tests, passing the gas through a 1-liter chamber at flow rates ranging from 0.35 to 1.10 liter/min. Changing the flow rates between 0.6 to 0.8 liter/ min did not cause a noticeable effect, although the activity changed noticeably. Thus, if the effect of actinon and radon must be taken into account, the flow rate must be kept constant. An increase of the Ra/sup 223/ and Ra/sup 226/ concentrations resulted in the decrease of the accuracy of the measurements which became dependent on the amount of Ra/sup 224/ present.