activation cross-section

Activation cross-section refers to the measure of the probability that a specific nuclear reaction will occur when a target nucleus is hit by a particle, such as a neutron or proton. It’s like the effective "target area" that determines how likely the particle is to cause a reaction, such as creating a new isotope or activating the material. The larger the cross-section, the higher the chance of activation happening under given conditions. This concept is important in nuclear physics and engineering, for instance, when designing reactors or managing radiation safety.