The cloud chamber, also known as the Wilson chamber, is used for detecting particles of ionizing radiation.

Invention

Charles Thomson Rees Wilson (1869-1959), a Scottish physicist, is credited with inventing the cloud chamber in 1900. In Wilson's original cloud chamber the air inside the sealed device was saturated with water vapor, then a diaphragm is used to expand the air inside the chamber. This cools the air and water vapor starts to condense. When an ionizing particle passes through the chamber, the water vapor condenses on the resulting ions and the trail of the particle is visible in the vapor cloud. Wilson, along with Arthur Compton, received the Nobel Prize for Physics in 1927 for his work on the cloud chamber.

Other chambers

The diffusion cloud chamber was later developed in 1936 by Alexander Langsdorf. This chamber differs from the expansion cloud chamber in that it is continuously sensitised to ratiation and that the bottom must be cooled to a rather low temperature, generally as cold as or colder than dry ice.

A refinement of the design is the bubble chamber.

External references

• How to Build a Cloud Chamber http://www.lns.cornell.edu/~adf4/cloud.html