The kinetic energy is the energy of motion, the energy an object possessed, e.g. a nucleon, a nucleus, an atom or another particle, because of its motion.

Lifetime is the mean life of a particle or in case of a radioactive nucleus equal to its decay time.

See also Half-Life, Decay.

The mass number is the total number of protons and neutrons (also total nucleon) in the nucleus.

See also Atomic Mass Unit, Atomic Mass.

Metastable isomers are produced through nuclear reactions. The excited state of the nucleus will de-excite by emission of gamma rays until the nuclear ground state is reached.
Isotopes in a metastable condition are designated with a 'm', for example 99mTc.

Nuclear reaction in which a neutron enters the nucleus and a proton is emitted.