Skip to main content
Select Source:

cloud chamber

cloud chamber, device used to detect elementary particles and other ionizing radiation. A cloud chamber consists essentially of a closed container filled with a supersaturated vapor, e.g., water in air. When ionizing radiation passes through the vapor, it leaves a trail of charged particles (ions) that serve as condensation centers for the vapor, which condenses around them. The path of the radiation is thus indicated by tracks of tiny liquid droplets in the supersaturated vapor. The cloud chamber was invented c.1900 by C. T. R. Wilson. In the type devised by him, which is often called the Wilson cloud chamber, air or another gas is saturated with water vapor and enclosed in a cylinder fitted with a transparent window at the top and a piston or other pressure-regulating device at the bottom. When the pressure in the chamber is suddenly reduced, e.g., by lowering the piston, the gas-vapor mixture is cooled, producing supersaturation. Cloud chambers of this design are sometimes called the pulsed type, since they do not maintain a continuous state of supersaturation of the vapor. A more recent design is the diffusion cloud chamber. In this device a large temperature difference is maintained between the top and bottom of the chamber, usually by cooling the bottom of the chamber with dry ice. The gas in the chamber, usually air, is saturated with a vapor, usually alcohol; the air-vapor mixture cools as it diffuses toward the cool bottom, becoming supersaturated. If the gas is kept saturated with a fresh supply of vapor, e.g., by an alcohol-soaked pad inside the top of the chamber, the operation of the chamber can be essentially continuous. One disadvantage of the cloud chamber is the relatively low density of the gas, which limits the number of interactions between ionizing radiation and molecules of the gas. For this reason physicists developed other particle detectors, notably the bubble chamber and the spark chamber.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"cloud chamber." The Columbia Encyclopedia, 6th ed.. . Encyclopedia.com. 19 Jun. 2018 <http://www.encyclopedia.com>.

"cloud chamber." The Columbia Encyclopedia, 6th ed.. . Encyclopedia.com. (June 19, 2018). http://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/cloud-chamber

"cloud chamber." The Columbia Encyclopedia, 6th ed.. . Retrieved June 19, 2018 from Encyclopedia.com: http://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/cloud-chamber

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

cloud chamber

cloud chamber Instrument used to detect and identify charged particles, invented in the 1880s by C. T. R. Wilson to study atomic radiation. The principle is the same as the bubble chamber, except liquefied gas is replaced by air supersaturated with water or alcohol vapour. This is cooled quickly to create droplets whose tracks form around the ionizing particle. The tracks are deflected by a magnetic field and photographed for analysis. In a diffusion cloud chamber, a large temperature difference is maintained between the top and bottom of the chamber.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"cloud chamber." World Encyclopedia. . Encyclopedia.com. 19 Jun. 2018 <http://www.encyclopedia.com>.

"cloud chamber." World Encyclopedia. . Encyclopedia.com. (June 19, 2018). http://www.encyclopedia.com/environment/encyclopedias-almanacs-transcripts-and-maps/cloud-chamber

"cloud chamber." World Encyclopedia. . Retrieved June 19, 2018 from Encyclopedia.com: http://www.encyclopedia.com/environment/encyclopedias-almanacs-transcripts-and-maps/cloud-chamber

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.