Ionization chamber for monitoring radioactive gas

Abstract From the Canadian patent

Abstract of the Disclosure, A small enclosed chamber with an electrostatically charged electret attached to the inner chamber wall. A filtered hole in the chamber permits radon or other radioactive gas to enter by diffusion. Positive or negative ions (depending on the polarity of the electret charge) formed in the chamber air by the decay of the radioactive gas move to and collect on the electret surface by virtue of its electrostatic attraction to ions of opposite polarity. These ions accumulate and cause a measurable reduction in the surface voltage of the electret which reduction is proportional to the time integrated concentration of the radioactive gas in the chamber. The electret …