barn
barn, unit of area used to measure the reaction cross section (generally different from the geometric cross section) of atomic nuclei and subatomic particles in the study of their interactions with other nuclei or particles. It is equal to 10β24 square cm. The name, coined by U.S. scientists, is derived from the proverbial phrase βside of a barn,β something easy to hit. See cross section.
This article was most recently revised and updated by William L. Hosch.
Citation Information
Article Title:
barn
Website Name:
Encyclopaedia Britannica
Publisher:
Encyclopaedia Britannica, Inc.
Date Published:
13 January 2015
Access Date:
November 13, 2026