How does a cloud chamber work?

A cloud chamber works by detecting the presence of charged particles through the formation of visible trails.

A cloud chamber is a device used to detect the presence of charged particles, such as electrons, protons, and alpha particles. It consists of a sealed container filled with a supersaturated vapour, typically a mixture of alcohol and water. When a charged particle passes through the vapour, it ionizes the molecules along its path, causing them to release electrons. These electrons then attach themselves to other molecules, forming a trail of ions.

As the trail of ions moves through the vapour, it causes a chain reaction of ionization, creating a visible cloud of tiny droplets. The droplets condense around the ions, making the trail visible to the naked eye. The trail can be photographed or recorded using a camera, allowing scientists to analyse the properties of the charged particle that caused it.

Cloud chambers are used in particle physics research to study the properties of subatomic particles, such as their mass, charge, and energy. They are also used in education to demonstrate the behaviour of charged particles and the principles of radiation detection. However, modern particle accelerators have largely replaced cloud chambers as a tool for particle physics research, due to their greater sensitivity and precision.