Abstract: A device and method for locating an electret in an electret-type radon gas detector, so it is wrinkle free, uses a sloped pedestal over which the electret sheet is placed. A ring with a beveled interior surface and a minor diameter smaller than the top of the pedestal is forced down over the electret sheet and pedestal, and into a groove surrounding the pedestal formed by a wall projecting from the base of the device. The movement of the ring causes the electret to stretch and eliminates any wrinkles. Also, forcing the ring over the pedestal causes the ring to rotate about its circular centroid axis and to dig into the walls of the groove, thus locking the assembly together.

Abstract: The detector system includes three substantially similar detectors each of which includes an ionization chamber having a pedestal therein mounting a charged electret. Two chambers are completely sealed except for an equalization aperture. The third detector has filtered inlet openings, which permit entry of radon gas, and responds to gamma rays and radon gas. Each detector is a canister including a lid having a round base surrounded by a cylindrical wall. The canister body is a circular base surrounded by a cylindrical wall that nests within the lid with a telescopic fit. A cylindrical pedestal assembly rests on the lid base and concentrically sandwiches the canister body between the pedestal assembly and lid. A press-fit holds these three elements together. The charged electret is mounted on the platform by a retaining collar that holds the electret with a press-fit.

Abstract: The device is a collapsible alpha track registration detector which will cost less to use and which can be used for measuring radon concentration over short and long term exposure times. The device includes a collapsible housing, defining an interior volume, in which is a strip of track registration material which forms damage tracks along paths traversed by alpha particles emitted during radioactive decay. The strip is retained within the housing on a cardboard holder to locate the strip at a predetermined location within the housing. The housing is a combination of a gusseted plastic bag and cardboard such that when collapsed it is a flat container but when in use it appears as a prism. The selected cardboard and plastic bag block particles and radon daughter products while admitting air and radon to the interior of the housing. The plastic bag has a hole to allow air to enter when being placed in use but the hole is sealed to one of the cardboard faces which prevents unwanted leakage.

Abstract: A system for measuring the cumulative amount of radiation received by a person includes a radiation monitoring electret. This electret is supported on a first conductive plate and preferably is positioned within a protective cavity such that it is not discharged by non-radiation sources. Measurement of the charge decrease on the electret over time is achieved by a null method. In particular, a second plate in the monitoring device located over the electret, or the electret itself, is vibrated and an A.C. amplitude modulation detector produces an output signal created by the alternating electric field due to the vibration. A D.C. voltage of opposite charge is then applied to the first conducting plate on which the electret is supported. This field is increased until it cancels the A.C. field above the electret. When this null occurs, the applied D.C. voltage is equal to the charge on the electret. Using this null technique the electret charge can be accurately measured without contacting the electret.