Cloud Chamber

Published: March 10, 2023

I built a cloud chamber to watch particle tracks form in vapor. The particle itself is invisible; the trail it leaves is large enough to see.

Inside an alcohol cloud chamber, a charged particle ionizes gas along its path. Supersaturated vapor condenses around those ions, forming a line of tiny droplets. Lighting makes those droplets stand out against the dark background. Harvard’s demonstration explains the mechanism; ICTS’s experiments cover the setup and illumination.

A track is a temporary record of something passing through the chamber. Its shape, length, and width give you something to examine before it disappears.