Electret ion chambers become gamma monitors when sealed in a radon leak tight enclosures. Usually sealable Mylar bags or any other enclosures are used. These provide integrated gamma exposure over a time, in units of mR or nGy. Dividing such exposure by exposure period leads to the average exposure rate.

Chambers being made of electrically conducting plastic, these provide energy independent response. These have been used in the place of TLDs. certain areas where low energy gamma emitters such as Americium-241, EICs provide superior performance over TLDs. For very low energy applications the EICs with thin windows, such as 7 mg/cm2 thick carbon coated Tyvek, are used. With a choice of different chamber volumes and electrets, a wide variety of sensitivities and ranges are possible. For more information, please contact REI for details. Following publications provide additional information: