| 摘要 |
Disclosed is an electrostatic capture type radon-measuring apparatus, which includes a supporting circular cylinder supported on a supporting table with an axis of the cylinder extending substantially vertically. A positive electrode has a curved surface extending convexly upward from the upper end of the supporting cylinder. A lower positive electrode of a truncated cone shape has open upper and lower ends and extends as narrowed downward from the upper end of the supporting cylinder. A negative electrode has an upper end thereof located in the vicinity of the lower end opening of the lower positive electrode. A solid track detector is covered with an electro-conductive thin film having alpha ray permeability and is mounted on the negative electrode. A cover is provided on the supporting table and encloses the supporting cylinder, upper and lower positive electrodes, negative electrode and solid track detector. The cover has an air-ventilating portion provided with a filter which does not permit the passage of daughter nuclides of radon and thoron.
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