How to reenact a famous particle physics experiment with nothing but party supplies

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One of the first ways physicists ever "saw" charged particles was using a cloud chamber. It was a chamber full of gas so close to condensing into liquid that the movement of charged particles through it caused the liquid to condense and trace the trail of the particles. Pretty fancy, huh? You can make one with party supplies.

With a few leftover party supplies you can make a cloud chamber, one of the most amazing tools in all of physics. Yes, really. First, you'll need to grab one of those clear plastic cups. Didn't use a clear plastic cup in your last party? Have another party. Or just get the cup. You can also use a terrarium, a big clear glass, or any clear, smooth, enclosed container. Grab some cloth, either the kind you used to make welcome signs, or the jacket that someone left behind, and cut a piece of cloth to fit one end of the container. The best cloth is felt. Use tape or some kind of sticky stuff (there's always that after parties) to stick the cloth to the container. Next? Soak that cloth with alcohol. (Technically isopropyl alcohol is best, but try it with vodka to be sure.)

Only a few steps left. Grab some dry ice and the nonstick metal pan you used to make the cake. (What do you mean you don't have dry ice and cake at your parties? Miss Manners would weep for you.) Shovel the dry ice under the pan, and invert the cup over the pan. Kill the lights (except for a small light source pointing right at the chamber) and wait.

What is happening? The warm alcohol at the top evaporates and drifts down. The dry ice cools it considerably, and it is just waiting for a chance to condense. The smooth plastic gives it very little to condense onto. As charged particles move through the chamber, they often knock some charge off the molecules inside, creating ions. These newly-charged ions attract alcohol particles and create tiny wisps of cloud.


Image: NASA/GRC/Bill Bowles
Via The Naked Scientists and Dr. Suzie Sheehy.