A cloud chamber is a particle detector that makes invisible charged particles visible by capturing the trails they leave as they move through a supersaturated vapor.
How It Works:
- The chamber contains a gas saturated with alcohol vapor or water vapor, cooled to a temperature just below condensation.
- When a charged particle (like an alpha or beta particle) passes through, it ionizes the gas molecules along its path.
- The ions act as condensation nuclei, causing the vapor to condense into tiny droplets around the ions.
- This condensation forms visible tracks or trails that reveal the particle’s path, direction, and sometimes energy.
Key Features:
- The shape and thickness of the trails can help identify the type of particle.
- Different particles produce distinctive track patterns: straight lines, spirals, or zigzags.
- The chamber can be placed in a magnetic field to bend charged particle paths, allowing measurement of their momentum and charge.
Applications:
- Early experimental tool for studying radioactivity and cosmic rays.
- Educational demonstrations of subatomic particles and their behavior.
- Precursor to modern particle detectors like bubble chambers and wire chambers.
The cloud chamber offers a direct and visual way to observe fundamental particles and their interactions, bridging abstract particle physics concepts with tangible observations.