secular equilibrium
A type of radioactive equilibrium in which the half-life of the precursor (parent) radioisotope is so much longer than that of the product (daughter) that the radioactivity of the daughter becomes equal to that of the parent with time.
stable equilibrium, equilibrium in which, after every small perturbation, the original state will tend to be restored.
transient equilibrium, a type of radioactive equilibrium in which the half-life of the parent radioisotope is longer than that of the daughter so that the ratio of activities of parent and daughter become constant as they decrease with time.
Unstable equilibrium, equilibrium in which the response to a small perturbation will tend to make the perturbation greater (e.g., a logged feedback process of zero order).
Dictionary > Secular equilibrium
