interaction cross section

An interaction cross section is a way to measure how likely a particle, like a proton or neutron, is to collide with another particle or target, such as a nucleus. Think of it as an effective “target size” that quantifies the probability of an interaction occurring. A larger cross section means a higher chance of collision, while a smaller one indicates it's less likely. This concept helps scientists understand and predict behaviors in nuclear reactions, particle physics experiments, and cosmic ray interactions by providing a standardized way to describe interaction likelihoods.