Caption

Bubble chamber particle tracks. Coloured bubble chamber view of an electromagnetic shower (centre). This has been produced by a muon neutrino (entering from the left) interacting with a neutron at the border of the large circle. The tracks are caused by particles moving through superheated liquid, which will not boil until it is disturbed. The passage of sub-atomic particles provides this disturbance, and they leave tracks of minute bubbles in their wake. These tracks can be photographed and studied. The "electromagnetic shower" occurs when by-products of the interaction disturb the surrounding liquid. Data from the Big European Bubble Chamber (BEBC) at CERN.