Neutron

Name:
Neutron
Detailed information:
Discovered by Chadwick in 1932, the neutron is a fundamental particle of matter having a mass of 1.009 but no electric charge. It is a constituent of the nucleus of all elements except hydrogen, the number of neutrons present being the difference between the mass number and the atomic number of the element. Neutrons may be liberated from the nucleus by fission of uranium-235, plutonium, and a few other elements, each nucleus yielding an average of 2.5 neutrons; they can also be produced by bombardment of other elements, e.g., beryllium with positively charged particles.Because free neutrons are uncharged they have tremendous penetrating power as a result of their electrical neutrality; hence, they have a highly damaging effect on living tissue, requiring the use of shielding of all equipment in which they are produced. Neutrons directly emitted from atomic nuclei are termed fast; these bring about the chain reaction in the atomic bomb. In a nuclear power reactor, where a less rapid reaction is desired, the energy of fast neutrons is partially absorbed by the moderator, and the neutrons so retarded are called slow or thermal.See Electron; Proton; Fission.

Use:

Nuclear fission; manufacture of plutonium and radioactive isotopes; activation analysis.