A cloud chamber shows tracks of alpha radiation particles. Dry ice (frozen carbon dioxide) and propan-2-ol (isopropanol) are used to create a supercooled and supersaturated vapour of alcohol. Alpha particles emitted from an alpha source are extremely ionising, and ionise air molecules. (Ionising in this case means removing an electron from an air molecule). The positively charged air molecule then attracts a propan-2-ol molecule. A dipole (or charge imbalance between the two ends of the molecule) is induced in the propan-2-ol molecule which then attracts another propan-2-ol molecule and so on creating a white track as the alpha particle travels along, ionising many air molecules.
A video of the tracks is available by clicking here.
Notice that the tracks (i.e the alpha particles) travel in a straight line (as no magnetic field is present).
© 2016 Dr Matthew French All rights reserved.