(1) A station in a penetrant inspection processing line where the developer is applied by creating a cloud of developer that envelops the test component. (2) A device for detecting and measuring radioactivity and radiation. The cloud chamber was invented by Charles Wilson in 1911 and it makes it possible to visually see and photograph the path of ionizing radiation.(Basic Science/Radiography/detectionmeasurement/cloudchamber_popup.htm)

apparatus that detects high-energy particles passing through a supersaturated vapor; each particle ionizes molecules along its path and small droplets condense on them to produce a visible track

a device that makes it possible to track the movements of fundamental particles