Svar:
Engelska Wikipedia (Radioactive_decay ):

There are many types of radioactive decay. A decay, or loss of energy, results when an atom with one type of nucleus, called the parent radionuclide (or parent radioisotope), transforms into an atom with a nucleus in a different state, or with a nucleus containing a different number of protons and neutrons. The product is called the daughter nuclide. In some decays, the parent and the daughter nuclides are different chemical elements, and thus the decay process results in the creation of an atom of a different element. This is known as a nuclear transmutation.

Man kan använda beteckningarna start- och slutnuklid men modernuklid och dotternuklid är bättre definierade. Modernuklid är alltså en kärna som sönderfaller och dotternuklid är sönderfallsprodukten.

Se fråga 17148 för en definition av nuklid.
/Peter E

Nyckelord: radioaktivt sönderfall [38];