Cloud Chamber
From UO Physics Demonstration Catalog
Return to Nuclear Physics
Description:
The cloud chamber makes it possible to view the tracks left by particles emitted by a radioactive source. The cloud chamber consists of a lower chamber that can be filled with Liquid Nitrogen. An upper chamber sits on top of the Liquid Nitrogen chamber. The Upper Chamber has a small amount of ethanol on the bottom, on the small shelf on the side and the felt pads on the top. This creates a saturated alcohol vapor indie the chamber. The alcohol can easily condense on the cold metal plate on the bottom if a charged particle is encountered. A high voltage power supply is connected to the chamber plates.
To enhance visibility, a bright light source from a projector shines into lower of the upper chamber. Once the plate at the bottom of the observation chamber cools down, due top the Liquid nitrogen in the bottom and the high voltage is initiated, the area near the plate becomes supersaturated with alcohol vapor and tracks will become visible as the particles from background radiation cause the alcohol to condense. Add the radioactive rod that is a Thorium source into the chamber, and you will see tracks coming from the rod. It is possible to distinguish between alpha and beta due to the length and paths of different tracks.
SAFETY NOTE: DO NOT TOUCH THE METAL PART OF THE RADIOACTIVE ROD. YOU CAN WEAR LATEX GLOVES AND BE SURE TO WASH HANDS IF CONTACT WITH THE ROD OCCURRED.
Location:
- Cloud Chamber: Shelf L-1
- High Voltage Power Supply: Shelf K-3
- liquid N2 dewars: Shelf E-4
- Ethanol: Chem Hood
