Cloud chamber facts
- Invented when: 1911
- Invented by who: Charles Thomson Rees Wilson
- What it does: detects charged particles moving through the detector
Cloud chambers are some of the most satisfying particle detectors. You can observe particles in real time with your own eyes, how cool is that? Since their invention they have been overtaken by other types of detectors that have better performance and aren’t used in modern high energy physics experiments.
What is most fun, you can make a cloud chamber yourself. Lots of people have made it for themselves. Here is one set of instructions. These instructions are the easiest I could find, the trickiest part is to get dry ice.
How does it work? A sealed chamber contains a supersaturated vaper of (most commonly) alcohol. When a charged particle traverses this gas, it separates the charges (electrons and ions) of the gas (process called ionization). The ions create condensation and we see a cloud like trail of the particle. This is how the positron was first discovered in 1932. Muons and kaons were also discovered thanks to cloud chambers.
These days, cloud chambers are mostly used in teaching physics, not so much in active research anymore. The negative of this technology is the precision and recording of particle tracks. The only way to record particle tracks with cloud chamber is to take a photograph of the trail and then analyze it visually. Modern detectors can record the electronic signal and store it with much better precision. However, cloud chambers served to a great advancement of particle physics and are a very cool technology.
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