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The cloud chamber, also known as the Wilson chamber, was invented in 1911 by a Scottish physicist Charles Thompson Rees Wilson. It serves as a particle detector for ionizing radiation by utilizing a sealed environment containing a supersaturated vapor of water alcohol. When a charged particle enters the chamber, it interacts with the gas molecule, knocking off electrons via electrostatic forces. This process leaves a trail of ionized gas particles that act as condensation nuclei, forming visible liquid droplets that reveal the particle’s trajectory.
The spark chamber is another type of detector that visualizes the paths of subatomic particles, but it operates using high-voltage electricity rather than vapor. It consists of stack of metal plates immersed in an inert gas, such as neon. When a charged particle, such as cosmic ray, passes through the plates, it leaves a trail of ions that triggers a series of bright, visible along its path.
While both instruments make invisible particles visible to the naked eye mechanisms differ: the cloud chamber relies on the condensation of supersaturated vapor, whereas the spark chamber uses an intense electric field to create luminous discharges. Eventually, these visual methods were replaced by electronic detectors, such as the multi-wire proportional chamber used in the OMEGA spectrometer, which allowed for faster data collection and more precise digital analysis.