Subsoil radioactive gas measuring system

Abstract

Radioactive gas, particularly radon, is measured in the subsoil environment by electrostatically charging one or two electrets and placing the electret(s) within a chamber having openings protected by a filter which permits gas to flow through the openings while preventing particles from flowing through the openings. The chamber with the electrostatically charged electret(s) and the detector is placed in a receiver formed within the hollow wall of an elongated probe. Foam cushions surround the chamber and assist in the filtering. An open material, such as steel wool, holds the foam in place and the next lower section of the probe holds the steel wool in place. When sampling is done at only one level, the next lower section is the soil moving nose of the probe. Holes in the side wall near the nose admit subsoil gas into the receiver. When it is desired to sample radioactive gas at several levels, additional sections of the probe have receivers for holding additional chambers and openings near the bottom of each section admit gas into the receivers. After leaving the probe in the soil for a predetermined period, the probe is removed and disassembled. The chamber is removed from the receiver and the surface charge on the detector is measured. Changes in the surface charge are compared with known relations between changes in surface in radioactive decay in the chamber to give amount of radioactive gas that has decayed in the chamber.