Wilson's Cloud Chamber is the classical pattern where alcohol saturates a pad in the chamber and a vacuum pump (reversed tyre pump) is used to draw a partial vacuum to super saturate the remaining air with alcohol vapour.

An Alpha 'pin source' in the chamber emanates particles that ionise the air particles along the path. The alcohol vapour condenses on these ionised paths to display miniature foggy tracks inside the chamber. These tracks indicate the path the Alpha particles took.

A light source is required (microscope lamp) to illuminate the cell and a 'pin source' of Alpha material is required.  

Instruction Sheet