In the present paper we will introduce spallation as an intensive source of neutrons.
Spallation refers to a non-elastic nuclear interaction induced by high energy particles in which several secondary particles are produced.
Two stages are involved in the spallation collision process, the first-collisions of the incident particle with individual nucleons inside the nucleus (particle cascade), and the second - the evaporation and fission phase. Important choices are discused like particle type, (as projectiles protons are preferred to heavier ions) and target materials (tantalum, tungsten and lead are libely to be used due to their properties).
The induced radioactivity, neutron production, and kinetic energy are also taken into cosideration.
Radioactivity produced in the target of a spallation neutron source can be expressed by saturation activity which corresponds to the total decay rate after prolonged irradiation.