Commissariat a L'energie Atomique

Marc Merelli

Jean Duchene

Patrick Burghoffer

Jean Charuau

Raymond Prigent

Jacques Allain

Francois Cliquet

Pierre Boulay

Process for the detection of atmospheric contamination by alpha particle aerosols eliminating the background noise due to radon daughter nuclei, of the type consisting of collecting, by circulation of the atmospheric air, the alpha particles to be detected on a filter placed in front of a detection and counting system, wherein there is discrimination between the alpha particles present in the atmosphere coming from a polluting source and which it is wished to detect and count and the alpha particles constituting the background noise and which are normally present in the atmosphere, on the basis of their different grain sizes. The invention also relates to a portable detector for performing the aforementioned process. Application to monitoring the ambient air of laboratories, etc.

Process and apparatus for detecting atmospheric contamination by alpha

Ionization chamber making it possible to measure high energy gamma radiation, wherein it comprises a tight cylindrical enclosure containing an ionizable gas, and several coaxial cylindrical electrodes, which are insulated from one another, and are positioned within the enclosure and are raised to different potentials, so as to produce an electrical field in the enclosure, whereby the innermost electrode is formed by a solid cylinder, the outermost electrode is formed by a solid tube and the intermediate electrodes are formed by a perforated tube.

Ionization chamber making it possible to measure high energy gamma

A leak-tight cylindrical metal casing filled with an ionizable gas contains a plurality of modules each having the function of an independent ionization chamber. Electrically insulated resilient means serve to maintain each module in position both radially and longitudinally within the casing. A central cylindrical core within each module serves as a support for two concentric cylindrical electrodes whose opposite faces are coated with boron-10.

Modular ionization chamber of the boron-coating type

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Gif sur Yvette, France

Marc Merelli