How To Build Cloud Chamber (Particle Detector)

Cloud Chamber is the earliest and the easiest particle detector that can be build by everybody.
If you are interested only how it works, scroll to bottom to see videos.

The first version of this device has been invented by Charles Thomson Rees Wilson. He has been awarded Nobel prize for his discovery in 1927.

Device opened door to literally seeing radioactive decay of unstable isotopes. It was used to discover many unknown new particles: positron, muon, pion and kaon to name a few.

Diffusion Cloud Chamber requires gradient of temperature inside of chamber. At the top of chamber there must be hot, and on the bottom of chamber cold.
To cool down usually there is used dry ice (which has temperature -78.5 °C). More expensive to build, but cheaper in usage, version uses Peltier Cooler.

To create Cloud Chamber we will need aquarium, plate of Styrofoam, clean sheet of Aluminum (size of the bottom of chamber or slightly higher to bend around chamber), black electrical tape, isopropyl alcohol (it's easy to buy in electronic equipment shop, sold as IPA cleaner), felt.

In below photos of Cloud Chamber there was used:

Cut Styrofoam to two equal pieces with size 500 mm x 350 mm. It will be bottom of device.

Cut hole in second piece of Styrofoam, enough for aquarium. It will be place where we will put dry ice.

Cover one side of Aluminum sheet by black electrical tape. Because of contrast it'll be easier to see particle traces.

Put layer of dry ice and cover it by sheet of Aluminum.

Attach piece of felt to inside of aquarium, and fill it by a bit of isopropyl alcohol.

Cover it by aquarium up side down.

Illuminate top of chamber by strong light to create temperature gradient. The rest should be in darkness. After a while we should start seeing traces leaved by cosmic rays.

You can also attach pipe with syringe with isopropyl alcohol. It will allow further filling felt by IPA without having to wait for de-encapsulation of chamber.