A cloud chamber allows the observation of the tracks of high-speed particles as they pass through a saturated vapor that condenses to form drop around ions left in the particle's wake. Cloud chambers were an early type particle detector that provided the prototype for many modern particle detectors. The cloud chamber was designed and first constructed by British physicist Charles T. R. Wilson (1869-1959) in 1896. Wilson's scientific curiosity and ability to see beyond the immediate experiment gave scientists their first look at the world of particle physics as represented in a cloud chamber.

The vapor in a cloud chamber cools via adiabatic expansion. Accordingly, cloud chamber trails left by particles look somewhat like the vapor trails of jet aircraft. Just as these atmospheric vapor trails can remain in the sky for several minutes after the plane has passed and thereby provide a record of the plane's...