Neutron:

Neutrons have no electrical charge and have nearly the similar mass as a proton (a hydrogen atom nucleus). The neutron is hundreds of times larger compare to an electron, other than one quarter the size of an alpha particle.  A source of neutrons is primarily nuclear reactions, like as fission, but they are also generates from the decay of radioactive elements.  Since of its size and lack of charge, the neutron is fairly hard to stop, and has an associatively high penetrating power.

Neutrons might collide with nuclei causing one of the following reactions: elastic scattering, inelastic scattering, fission or radiative capture,.

Inelastic scattering causes a few of the neutron's kinetic energy to be transferred to the target nucleus in the form of kinetic energy and a few internal energy. That transfer of energy slows the neutron, other than leaves the nucleus in an excited state. The excitation energy is emitted as a gamma ray photon. The interaction among the neutron and the nucleus is best elaborate through the compound nucleus mode; the neutron is captured, and then re-emitted from the nucleus along within a gamma ray photon. This re-emission is measured the threshold phenomenon. Neutron threshold energy varies from infinity for hydrogen, to about 6 MeV for oxygen and to less than 1 MeV for uranium.