Is there equivalence equation between cross section & half life? For beta decay, we usually use half life to describe how fast or slow the decay undergo. For nuclear reaction, we use cross section to describe the possibility of reaction. In a sense, they reflect the same root physics spirit. Is there equation to associate half life and cross section? So as to assess nuclear reaction how fast or slow. For example, Co-60 half life about 5 years, if other reaction can consume half reactants in 5 years, then its cross section can be regarded as equivalent to half life 5 years.