Cloud Chamber
A historic particle detector consisting of a sealed chamber containing supersaturated vapor where passing ionizing radiation forms visible condensation trails.
Governing formula
Condensation droplets forming along ion trails
SI unit
Visual Particle Tracks
In depth
Invented by Charles Wilson in 1911. Fast charged particles ionize gas atoms along their path; these ions act as condensation nuclei for alcohol vapor, creating visible white droplet trails revealing particle trajectories.
Examples in the real world
Carl Anderson discovering the positron in 1932 by observing curved particle tracks in a magnetic cloud chamber.