Editing Mean free path (section)

===Nuclear and particle physics===
In particle physics the concept of the mean free path is not commonly used, being replaced by the similar concept of [[attenuation length]].  In particular, for high-energy photons, which mostly interact by electron–positron [[pair production]], the [[radiation length]] is used much like the mean free path in radiography.

Independent-particle models in nuclear physics require the undisturbed orbiting of [[nucleon]]s within the [[Atomic nucleus|nucleus]] before they interact with other nucleons.<ref>{{cite book|chapter-url=http://www.res.kutc.kansai-u.ac.jp/~cook/NVSIndex.html|title=Models of the Atomic Nucleus|last=Cook|first=Norman D.|date=2010|publisher=[[Springer Science+Business Media|Springer]]|isbn=978-3-642-14736-4|edition=2|location=Heidelberg|page=324|chapter=The Mean Free Path of Nucleons in Nuclei}}</ref>

{{Quote|text=The effective mean free path of a nucleon in nuclear matter must be somewhat larger than the nuclear dimensions in order to allow the use of the independent particle model. This requirement seems to be in contradiction to the assumptions made in the theory ... We are facing here one of the fundamental problems of nuclear structure physics which has yet to be solved.|sign=John Markus Blatt and [[Victor Weisskopf]]|source=''Theoretical nuclear physics'' (1952)<ref>{{Cite book|last=Blatt|first=John M.|last2=Weisskopf|first2=Victor F.|date=1979|title=Theoretical Nuclear Physics|language=en-gb|doi=10.1007/978-1-4612-9959-2|isbn=978-1-4612-9961-5|url=https://digital.library.unt.edu/ark:/67531/metadc1067172/}}</ref>}}