The black-and-white photos shown above were taken using a 35mm camera positioned over the dry ice cloud chamber. A small ball of paint containing radium was used as the source for particles. The radium paint was scraped from old glow-in-the-dark watch faces and glued into a small ball on the end of a wire that was then stuck in a small plastic cap. This project demonstrated how cloud chambers functioned and how physicists had used them to study subatomic particles.

The sharp white lines in the photos above were created by alpha particles (two protons and two neutrons--essentially the positively charged nucleus of a helium atom). The fuzzier, softer white lines were created by beta particles negatively-charged free electrons. A beta particle is weaker in charge and mass than the alpha particle--hence the weaker, fuzzier trail it leaves in the mist. Other types of particles and rays leave other distinctive patterns or tracks. By varying the source of the radioactivity, and by using magnets, electrically charged fields and other interventions, early twentieth century physicists were able to use cloud chambers to identify and explore a variety of new subatomic particles, waves, and properties. C.T.R. Wilson was awarded the Nobel Prize in Physics in 1927, for inventing the cloud chamber and for recognizing its use for studying ionization. Another physicist of that era, Ernest Rutherford, described the cloud chamber as "the most original and wonderful instrument in scientific history."