Build your own particle detector to make ionising particles visible and study the properties of different particle tracks.

Although we can't see them, ionising particles are part of our everyday life. For example, cosmic particles interacting with the upper layers of the Earth’s atmosphere produce showers of new particles, some of which reach ground level. Naturally occurring radioactive elements in the air emit alpha particles. Through interaction with certain detector materials, we can make tracks of ionising particles visible. 

In this workshop, participants build their own particle detector, a so-called cloud chamber, using dry ice and isopropanol to make cosmic particles and natural radiation visible. They study the properties of the different particle tracks before presenting and discussing their observations.

The cloud chamber was one of the first particle detectors and was used to discover the positron (Nobel Prize 1932) and the muon (Nobel Prize 1936). Today, cloud chambers are only used in education. Modern particle detectors at CERN use similar principles of particle detection as cloud chambers (though different techniques) to explore the properties of particles.