Difference between revisions of "Cross section"

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[[Category:Basic concept]]
 
[[Category:Basic concept]]
 
[[Category:Wikipedia]]
 
[[Category:Wikipedia]]
The '''cross section''' for a given process is a measure for the rate of interactions that originate from the process that can be quoted independently of the experimental set-up of the scattering experiment itself. In a hypothetical experiment in which a flux of particles ''F'' (particles per square area per unit time) scatter at a rate ''R'' (scattered particles per unit time), the cross section is 𝜎 = ''R''/''F''.
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The '''cross section''' for a given process is a measure for the rate of interactions that originate from the process that can be quoted independently of the experimental set-up of the scattering experiment itself. It is denoted <math>\sigma</math>. In a hypothetical experiment in which a flux of particles <math>F</math> (incident particles per unit area per unit time) scatter at a rate <math>R</math> (scattered particles per unit time), the cross section is <math>\sigma = R/F</math>.
  
 
Cross sections are measured in units of area, where the special unit ''barn'' (b) is used with prefixes. A barn is 10<sup>−28</sup> m<sup>2</sup> (100 fm<sup>2</sup>). Cross sections at the [[LHC]] can range from hundreds of millibarns (the total cross section of proton-proton collisions) down to fb or smaller for rare processes that are still considered to be measurable.  
 
Cross sections are measured in units of area, where the special unit ''barn'' (b) is used with prefixes. A barn is 10<sup>−28</sup> m<sup>2</sup> (100 fm<sup>2</sup>). Cross sections at the [[LHC]] can range from hundreds of millibarns (the total cross section of proton-proton collisions) down to fb or smaller for rare processes that are still considered to be measurable.  
  
In calculations using natural units (with ''ħ''=''c''=1) area has dimensions of 1/energy-squared, so units of GeV<sup>-2</sup>. The conversion is 1 GeV<sup>-2</sup> = 0.389 mb.
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In calculations using [[natural units]] (with <math>\hbar = c = 1</math>), area has dimensions of 1/energy-squared, so units of [[GeV]]<sup>-2</sup> may be used. The conversion is 1 GeV<sup>-2</sup> = 0.389 mb.
  
 
== Learn more ==
 
== Learn more ==
 
* [https://en.wikipedia.org/wiki/Cross_section_(physics) Wikipedia article]
 
* [https://en.wikipedia.org/wiki/Cross_section_(physics) Wikipedia article]

Latest revision as of 08:24, 7 April 2017

The cross section for a given process is a measure for the rate of interactions that originate from the process that can be quoted independently of the experimental set-up of the scattering experiment itself. It is denoted \sigma. In a hypothetical experiment in which a flux of particles F (incident particles per unit area per unit time) scatter at a rate R (scattered particles per unit time), the cross section is \sigma = R/F.

Cross sections are measured in units of area, where the special unit barn (b) is used with prefixes. A barn is 10−28 m2 (100 fm2). Cross sections at the LHC can range from hundreds of millibarns (the total cross section of proton-proton collisions) down to fb or smaller for rare processes that are still considered to be measurable.

In calculations using natural units (with \hbar = c = 1), area has dimensions of 1/energy-squared, so units of GeV-2 may be used. The conversion is 1 GeV-2 = 0.389 mb.

Learn more