Does anybody know of any good references that explain the concepts/mathematics behind cross sections particularly well? Websites, textbooks, whatever...
The Wikipedia article on ''cross section'' discusses some of the concepts regarding cross sections. Basically you can see it as some sort of ''effective'' area of the particle that is being scattered from. If the scattering particle gets within this ''effective'' area, there is a reaction. The Wiki article links among others to this page, which I found to be quite good: http://hyperphysics.phy-astr.gsu.edu/Hbase/nuclear/crosec.html#c2