In
nuclear physics and
nuclear chemistry, a
nuclear reaction is semantically considered to be the process in which two
nuclei, or else a nucleus of an atom and a
subatomic particle (such as a proton,
neutron, or high
energy electron) from outside the atom, collide to produce one or more
nuclides that are different from the nuclide(s) that began the process. Thus, a nuclear reaction must cause a transformation of at least one
nuclide to another. If a nucleus interacts with another nucleus or particle and they then separate without changing the nature of any nuclide, the process is simply referred to as a type of nuclear
scattering, rather than a nuclear reaction.