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ionization chamber n.
A chamber for detecting ionization of the enclosed gas, used for determining the intensity of ionizing radiation.
radiation detector used for determining the intensity of a beam of radiation or for counting individual charged particles. The device may consist of a gas-filled, cylindrical container in which an electric field is maintained by impressing a voltage that keeps the wall negative relative to a wire extending along the axis. When a photon or a charged particle enters the chamber, it converts some of the gas molecules to positive ions and electrons; under the influence of the electric field, these particles migrate to the wall and the wire, respectively, and cause an observable pulse of current to flow through the circuit joining these elements