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A particle detector used for detecting ionizing radiation. In its most basic form, it is a sealed environment containing a supersaturated vapor of water or alcohol, in which a mist can be seen where a charged particle interacts with the mixture and it ionizes it.

The original cloud chamber of C. T. R. Wilson at the Cavendish Lab, Cambridge, England.

A particle detector used for detecting ionizing radiation. In its most basic form, it is a sealed environment containing a supersaturated vapor of water or alcohol, in which a mist can be seen where a charged particle interacts with the mixture and it ionizes it.

Fig. 3: A diffusion-type cloud chamber. Alcohol (typically isopropanol) is evaporated by a heater in a duct in the upper part of the chamber. Cooling vapor descends to the black refrigerated plate, where it condenses. Due to the temperature gradient, a layer of supersaturated vapor is formed above the bottom plate. In this region, radiation particles induce condensation and create cloud tracks.

A particle detector used for detecting ionizing radiation. In its most basic form, it is a sealed environment containing a supersaturated vapor of water or alcohol, in which a mist can be seen where a charged particle interacts with the mixture and it ionizes it.

Fig. 4: How condensation trails are formed in a diffusion cloud chamber.