Decay chain
In nuclear science, the
decay chain refers to the radioactive decay of different discrete radioactive decay products as a chained series of transformations. Most radioactive isotopes do not decay directly to a stable state, but rather undergo a series of decays until eventually a stable isotope is reached. Decay stages are referred to by their relationship to previous or subsequent stages. A
parent isotope is one that undergoes decay to form a
daughter isotope. The daughter isotope may be stable or it may decay to form a daughter isotope of its own. The daughter of a daughter isotope is sometimes called a
granddaughter isotope. The time it takes for a single parent atom to decay to an atom of its daughter isotope can vary widely, not only for different parent-daughter chains, but also for identical pairings of parent and daughter isotopes. While the decay of a single atom occurs spontaneously, the decay of an initial population of identical atoms over time
t, follows a decaying exponential distribution,
e−λt, where λ is called a decay constant.