Electret ion chamber for radon monitoring

摘要

An electret ion chamber for monitoring radon comprises a housing having an electret holder and a cover. The cover is attached to a plunger which closes over the electret when the cover is in place and is removed from the electret when the cover is opened. The plunger effectively turns "on" and "off" the radon monitor with the opening and closing of the cap. In very short term and very long term radon monitors, this turn on and off feature is not needed.