Process and apparatus for detecting atmospheric contamination by alpha particle aerosols

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.