In its simplest form, a cloud chamber consists of a chamber containing saturated vapor and some liquid, one wall of the chamber (the window) being transparent, another retractable. Sudden retraction of this wall lowers the temperature, and the gas becomes supersaturated (and thus metastable). The passage of subatomic particles through the gas leaves a trail of ions that serve as seeds for condensation of the gas into droplets. These fog trails (condensation trails) may be illuminated by a beam of light against a black background photographed through the window.
The cloud chamber was further developed by Patrick Blackett for the observation of cosmic rays.
Related entry bubble chamber
Related category PARTICLE PHYSICS
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