The only thing better than watching an entertaining science project and learning something new is watching and learning it from someone a quarter of my age. Samatha, 6, explains in the video below how to quickly and easily build a “cloud chamber,” otherwise known as a cosmic ray detector, with some dry ice and household items.
Cosmic rays are very high-energy radioactive particles, mostly made up of electrons and muons. Humans cannot detect these cosmic rays with our five senses, but by setting up a cosmic ray detector, it is possible to create an environment in which the tiny rays are visible, resembling streams of light or trails behind an airplane.
Before digging into this cosmic ray detector project, some safety warnings are in order: This is a fairly safe project, but definitely be sure to protect your skin from the dry ice with insulated gloves. While this is a kid-friendly project, young ones should be aided by an adult when setting up the dry ice and supervised at all times. As Samatha shows us, you’ll need some rubbing alcohol, dry ice, a piece of felt, a plastic cup, Play-Doh, a metal pan, a flashlight, two magnets, and a styrofoam cooler lid. In addition to insulated gloves, it’s also a good idea to wear safety goggles and a protective apron.
This experiment works due to the electrical charge of cosmic rays. When an electrically charged particle moves through the space of the plastic cup, it comes into contact with vaporized rubbing alcohol and ionizes the vapor atoms. This causes a process of condensation, which then renders the trail of the cosmic ray visible to human eyes.
Samatha identifies three main types of visible trails in her cloud chamber: alpha particles, which have thick, small tracks; muons, which have thin and long tracks; and electrons, which have wiggly tracks.
Check out the video below, and for more detailed instructions, Samatha’s dad, Kranti Gunthoti, has posted this science experiment on Instructables.