ASSEMBLY FOR MEASURING AIRBORNE .alpha. ACTIVITY COLLECTED ON A FILTER BY COUNTING .alpha. RADIATION FROM THE FILTER BACK

摘要

Devices are known for measuring .alpha.-radiation produced by airborne particles, but in these devices the detectors are upstream of a filter used to collect the particles which means that the detectors are subject to dirt buildup from airborne particles. The present invention avoids this problem in that the detector is on the downstream side of the filter. The device includes a chamber into which air is sucked through the filter covering one end of the chamber. The filter is of a type through which .alpha.-particles may penetrate. The .alpha.-particles are detected by a scintillation screen and photodetector at the other end of the chamber.