Originally just an offshoot of nuclear physics, neutron physics soon became a branch of physics in its own right. It deals with the movement of neutrons in nuclear reactors and all the nuclear reactions they trigger there, particularly the fission of heavy nuclei which starts a chain reaction to produce energy. Neutron Physics covers the whole range of knowledge of this complex science, discussing the basics of neutron physics and some principles of neutron physics calculations. Because neutron physics is the essential part of reactor physics, it is the main subject taught to students of Nuclear Engineering. This book takes an instructional approach for that purpose. Neutron Physics is also intended for all physicists and engineers involved in development or operational aspects of nuclear power.