Cloud Chamber
[Can detect: Alpha, Beta and Gamma]
- Figure above shows a simple form of cloud chamber, a device which enables the tracks of charged particles to be seen.
- The felt ring round the top of the chamber is soaked in alcohol. The bottom of the chamber is cooled by 'dry ice' (solid carbon dioxide) to around -80 °C.
- As the alcohol vapour spreads downward through the chamber, it is cooled beyond the point at which it would normally condense.
| Alpha-particle tracks: |
Beta-particle tracks: |
Gamma-ray: |
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| Thick and straight, with the occasional deflection if an alpha particle collides with an air molecule. |
Thin and crooked. The particles cause much less ionization and, being light, are continually being pushed off; caused by air molecules nearby. |
Don't produce tracks as such. The tracks seen are those caused by electrons which have absorbed energy from photons and have escaped from atoms. |
