Question

The figure below shows the cross-section of a diffusion cloud chamber used to detect radiation from radioactive sources.

1. State the function of the following:
   1. Alcohol.
   2. Solid CO₂.
2. Explain briefly how the diffusion cloud chamber can be used to detect and identify alpha particles. 

Answer 1

1. Alcohol. - Alcohol condenses around the ions formed by the radiation to form the narrow tracks
2. Solid CO₂. - Cools the bottom of the chamber and also condenses alcohol below its normal temperature
3. Explain briefly how the diffusion cloud chamber can be used to detect and identify alpha particles. 
   • Sold CO₂ cools the bottom of the chamber alcohol vapourises and spreads through the chamber. It is cooled below its normal temperature in case of a radiation, air around the path of the radiation is ionized. Alcohol condenses around these ions to form a narrow cloud.