The cloud chamber is one of the earliest particle detectors ever created. It was invented by Scottish Physicist, Charles Wilson, who was attempting to study cloud formation when he discovered that he’d accidentally invented a particle detector! He went on to win a Nobel Prize for this discovery. Cloud chambers detect charged subatomic particles, like muons, electrons, and alphas. SNOLAB experiments are seeking interactions of other types of particles, namely neutrinos and dark matter.

Cosmic rays are subatomic particles coming from space that strike the Earth’s atmosphere and create a shower of secondary particles. These invisible particles constantly bombard the Earth’s surface and would interact with our detector at such a volume that it would mask the signal the detectors are looking for. In order to detect neutrinos or dark matter, it’s important to shield the experiments from cosmic radiation and other sorts of particles. This is why SNOLAB is located two kilometres underground.

For for information on how to build your own cloud chamber, visit our Education & outreach resources page: https://www.snolab.ca/outreach/resour...