Expansion cloud chamber for observing the paths of α-rays. Cover and sidewall are of plexiglas. With threaded hole for inserting the 226Ra, 4 kBq radiation cartridge (1006797), hinged absorption foil for opening and closing the beam outlet and carrying handle at the side.
By compressing the attached rubber ball and then allowing it to expand, a supersaturated isopropanol-water mixture is produced in the cloud chamber. Following that, the paths of the α-rays revealed by droplet formation are visible for 1 – 2 seconds in the light of an optical lamp.