We shall find circumstances and conditions in which this rule is not true. In all the examples given we assume that the number of protons and the number of neutrons is separately conserved.
We have accepted conservation of energy and momentum. Certain of these laws are obeyed under all circumstances, others are not. Additional conservation laws, not anticipated by classical physics, are are electric charge, lepton number and baryon number. Nuclear reactions are subject to classical conservation laws for charge, momentum, angular momentum, and energy (including rest energies). In analyzing nuclear reactions, we apply the many conservation laws.
Sometimes if a nucleus interacts with another nucleus or particle without changing the nature of any nuclide, the process is referred to a nuclear scattering, rather than a nuclear reaction.
Thus, a nuclear reaction must cause a transformation of at least one nuclide to another. A nuclear reaction is considered to be the process in which two nuclear particles (two nuclei or a nucleus and a nucleon) interact to produce two or more nuclear particles or ˠ-rays ( gamma rays).
