A unit of cross section used in particle physics; it is used to indicate the probability of a reaction between nuclear particles and atomic nuclei or other nuclear particles. One barn is equal to 10-28 m2 (10-24 cm2 ).
Many interesting cross sections are measured in pb (picobarns), which are equal to 10-12 barns. The physical cross sectional area of the nucleus of an atom is approximately 1 barn but depending on the reaction involved the actual reaction cross sectional area can vary over many decades of barns in size and are very dependent on particle energy.
Related categories PARTICLE PHYSICS
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