Tiny Particles Collide with Vapour Molecules

They are tinier than the tiniest of atoms, but they can change the world. Fill a box with cold vapour and see the tiny particles with your own eyes.

You are constantly bombarded with trillions of particles, but you cannot see them, as they are tinier than an atom. Some of the particles, such as muons and positrons, are produced when high- energy radiation from space collides with atoms in Earth’s upper atmosphere. Others, such as alpha particles, appear as radioactive substances decay.

In the world’s leading particle physics lab, CERN, scientists use vapourfilled chambers to detect the invisible particles. And you can do the same thing (with a little less detail but a LOT less electricity) in your own home.

Isopropanol evaporates at room temperature, and felt soaked in the stuff can quickly fill a closed chamber with the vapour. Cool the base with dry ice, and the air will be so saturated with vapour that it only takes slight external influence to make the vapour condense into small, visible droplets.

When the invisible particles pass through the chamber, they use their high energy to force electrons out of air molecules. The air becomes positively charged, and this charge attracts isopropanol molecules, which unite to form droplets. The invisible particles produce clear traces of small droplets, which you can see with the naked eye. And you can even tell which type of particle you see based on the shapes and sizes of the traces.