How does a bubble chamber work?

A bubble chamber works by detecting charged particles that pass through a superheated liquid.

A bubble chamber is a device used to detect charged particles, such as protons and electrons, that pass through a superheated liquid. The liquid is typically a mixture of alcohol and water that is heated to just below its boiling point. When a charged particle enters the chamber, it ionizes the liquid, causing it to boil along the path of the particle. This creates a trail of bubbles that can be photographed and analysed.

The superheated liquid in the chamber is kept at a constant temperature and pressure, which allows it to remain in a metastable state. This means that it is on the verge of boiling, but has not yet reached its boiling point. When a charged particle passes through the liquid, it creates a trail of bubbles that expand and rise to the surface, where they burst and release the gas that was trapped inside. This gas then condenses into a visible cloud that can be photographed and analysed.

Bubble chambers were first developed in the 1950s and were used extensively in particle physics research until the 1980s, when they were largely replaced by more advanced detectors such as the silicon strip detector. However, bubble chambers are still used in some experiments, particularly those that involve low-energy particles or rare events that require high sensitivity.