Demonstration of the "Cloudylabs" cloud chamber with some low activity radioactive sources. It works with 8 thermoelectric modules with a closed loop liquid cooler, so it can display the first particles within 1 min.
A magnet is put inside the machine, under the interaction surface, so during the whole video, a magnetic field is present and deflect the lightly charged particles (electrons).
More infos on http://www.cloudylabs.fr/