Cloud chamber

The cloud chamber, also known as the Wilson chamber, is used for detecting particles of condensation nuclei, around which a mist will form (because the mixture is on the point of condensation). The high energies of alpha and beta particles mean that a trail is left, due to many ions being produced along the path of the charged particle. These tracks have distinctive shapes (for example, an alpha particle's track is broad and straight, while an electron's is thinner and shows more evidence of deflection). When a vertical magnetic field is applied, positively and negatively charged particles will curve in opposite directions. For more detailed track-shape information, see bubble chamber.

Invention

Arthur Compton, received the Nobel Prize for Physics in 1927 for his work on the cloud chamber. This kind of chamber is also called a pulsed chamber, because the conditions for operation are not continuously maintained.

Other chambers

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

The bubble chamber similarly reveals the tracks of subatomic particles, but as trails of bubbles in superheated liquid. Bubble chambers can be made physically larger than cloud chambers, and since they are filled with much denser material, they reveal the tracks of much more energetic particles. These factors rapidly made the bubble chamber the particle detector of choice, so that cloud chambers were effectively superseded in fundamental research by the start of the 1960s.

References

Das Gupta, N. N.; Ghosh S. K. (1946). "A Report on the Wilson Cloud Chamber and its Applications in Physics". Reviews of Modern Physics 18: 225-365.