Electrostatic capture type radon measuring apparatus

• US 5,029,248 A
• Filed: 05/08/1989
• Issued: 07/02/1991
• Est. Priority Date: 05/10/1988
• Status: Expired due to Term

• Current Assignee: Okano Works Limited
• Original Assignee: Okano Works Limited
• Inventors: Miyake, Hiroshi
• Primary Examiner(s): Westin, Edward P.
• Assistant Examiner(s): CHU, KIM KWOK
• Application Number:
  US07/348,835
• Time in Patent Office: 785 Days
• Field of Search: 250/482.1, 250/472.1, 250/473.1, 250/393, 250/370.02, 250/255, 250/253, 313/93
• US Class Current: 250/253
• CPC Class Codes: G01T 5/10 Plates or blocks in which tracks of nuclear particles are made visible by after-treatment, e.g. using photographic emulsion, using mica
• CPC Class Codes: Y10S 250/02 Radon detection

Abstract

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 α 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.

Claims

1. An electrostatic capture type radon-measuring apparatus comprising:

a supporting circular cylinder supported on a supporting table with an axis of the supporting circular cylinder extending substantially vertically;

an upper positive electrode having a curved surface extending convexly upward from an upper end of the supporting circular cylinder;

a lower positive electrode of a truncated cone shape having open upper and lower ends and extending as narrowed downward from the upper end of the supporting circular cylinder;

p1 a negative electrode with an upper end thereof located in a vicinity of the lower end opening of the lower positive electrode;

a solid track detector covered with an electro-conductive thin film having α

ray permeability and mounted on the negative electrode; and

a cover provided on the supporting table and enclosing the supporting circular cylinder, upper and lower positive electrodes, negative electrode and solid track detector, the cover having an air-ventilating portion provided with a filter which does not permit passage of daughter nuclides of radon and thoron.

2. An electrostatic capture type radon-measuring apparatus according to claim 1 in which the upper positive electrode has a semispherical shape.

3. An electrostatic capture type radon-measuring apparatus according to claim 1 in which the lower positive electrode has a funnel shape.