Particle tracks in bubble chamber (A138/0095) Pillow

Bubble chamber particle tracks. Coloured image showing a collection of tracks left by subatomic particles in a bubble chamber. A bubble chamber is a container filled with liquid hydrogen which is superheated - momentarily raised above its normal boiling point by a sudden drop in pressure in the container. Any charged particle passing through the liquid in this state leaves behind a trail of tiny bubbles as the liquid boils in its wake. These bubbles are seen as fine tracks, showing the characteristic paths of different types of particle. The paths are curved due to an intense applied magnetic field. The tightly-wound spiral tracks are due to electrons and positrons.