放射性気体及び放射性エアロゾル濃度の精密測定 (I)

抄録

A new type radon meter is devised. Double wire netting is used for the external walls of the ionization chamber, and a vibrating reed electrometer and a self-recording ammeter measure the ionization current. Natural leak is very small and ions in flowing gas do not affect the ionization current density, which makes direct measurement of quickly decaying radioactive gases, thoron for example, and continuous observation of atmospheric radioactivity possible.
Comparison between the bubbling method and the boiling method for measuring the concentration of radon gas from standard radium solution is made, for thorough exhaustion of the gas is of great importance. In principle, the boiling method is superior, but as to the reproducibility, no difference is found so far.
Absorption of activated charcoal is applied for obtaining non-radioctive air. The charcoal proved to be almost perfect in trapping radon gas.
Brief description is given of the results of atmospheric radioactive observations made with the author's radon meter and an ordinary electrostatic precipitator.