| 摘要 |
PURPOSE: To obtain an installation-type radon and thoron discrimination and concentration measuring apparatus by which the concentration of outdoor radon can be measured by a method wherein the concentration of radon can be measured with high accuracy by excluding the influence of thoron and the electrochemical etching time and the shape of a container are designed optimally with a view to enhancing a measuring sensitivity. CONSTITUTION: In an installation-type radon and thoron discrimination and concentration measuring apparatus, a plastic film detector 7 which detectsα-rays on the surface and the rear surface is supported by a through-hole part 32 in a fixation stand 3, two kinds of hollow hemispheres, i.e., an upper bowl part 1 and a lower bowl part 4 whose diameter is smaller than that of the upper bowl part, are arranged and installed respectively so as to cover the plastic film detector 7 at the upper part and the lower part of the fixation stand 3, the air in the hollow hemisphere as the upper bowl part 1 is replaced by the open air, and the hollow hemispheres as the upper bowl part 1 and the lower bowl part 4 are ventilated via ventilation holes.
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