Neutron

A neutron is a subatomic particle, symbol or , that has no electric charge, and a mass slightly greater than that of a proton. The neutron was discovered by James Chadwick in 1932, leading to the discovery of nuclear fission in 1938, the first self-sustaining nuclear reactor (Chicago Pile-1, 1942), and the first nuclear weapon (Trinity, 1945).

thumb|An atomic nucleus is shown here as a compact bundle of the two types of nucleons, [[protons (red) and neutrons (blue). In this picture, the protons and neutrons are shown as distinct, which is the conventional view in chemistry, for example. But in an actual nucleus, as understood by modern nuclear physics, the nucleons are partially delocalized and organize themselves according to the laws of quantum chromodynamics.]] In physics and chemistry, a nucleon is either a proton or a neutron, considered in its role as a component of an atomic nucleus. The number of nucleons in a nucleus define

The antineutron is the antiparticle of the neutron with symbol . It differs from the neutron only in that some of its properties have equal magnitude but opposite sign. It has the same mass as the neutron, and no net electric charge, but has opposite baryon number (+1 for neutron, −1 for the antineutron). This is because the antineutron is composed of antiquarks, while neutrons are composed of quarks. The antineutron consists of one up antiquark and two down antiquarks.

low yield thermonuclear weapon

gives the angles for coherent and incoherent scattering from a crystal lattice

Ionizing radiation that presents as free neutrons

Neutronium (or element zero) is a hypothetical substance made purely of neutrons. The word was coined by scientist Andreas von Antropoff in 1926 (before the 1932 discovery of the neutron) for the hypothetical "element of atomic number zero" (with no protons in its nucleus) that he placed at the head of the periodic table (denoted by -).

atomic nuclear process

decay where a neutron is ejected from the nucleus

The slow neutron-capture process, or '''s-process', is a series of reactions in nuclear astrophysics that occur in stars, particularly asymptotic giant branch stars. The s''-process is responsible for the creation (nucleosynthesis) of approximately half the atomic nuclei heavier than iron.

In nuclear astrophysics, the rapid neutron-capture process, also known as the '''r-process', is a set of nuclear reactions that is responsible for the creation of approximately half of the atomic nuclei heavier than iron, the "heavy elements", with the other half produced largely by the s-process. The r-process synthesizes the more neutron-rich of the stable isotopes of even elements, and those separated from the beta-stable isotopes by those that are not often have very low s-process yields and are considered r-only nuclei; the heaviest isotopes of most even elements from zinc to mercury fall

Material that reflects neutrons

device that emits neutrons

process in which neutron radiation induces radioactivity in materials

nuclear reactors that serve primarily as a neutron source

concept related to neutron kinetic energy

the total length travelled by all free neutrons per unit time and volume

dislocation of atoms in a solid caused by neutron radiation

nonsurgical therapeutic modality for treating locally invasive malignant tumors

probability amplitude in quantum scattering theory

The tetraneutron is considered an unbound isotope with a lifetime around 10−22 seconds. The stability of this cluster of four neutrons is not supported by current models of nuclear forces. Recent empirical evidence is "consistent with a quasi-bound tetraneutron state existing for a very short time".

study of motions and interactions of neutrons with materials

physical phenomenon

intrinsic magnetic dipole moment of neutrons

scalar physical quantity

neutron emitted after a nuclear fission event, as a fission product daughter after beta decay, any time from a few milliseconds to a few minutes after the fission event

Scientific background leading to the discovery of the neutron and other subatomic particles

unit of reactivity for a nuclear reactor

neutron immediately emitted by a nuclear fission event

medical intervention

decay of a neutron when outside a nucleus

materials made radioactive by neutron activation

imaging process

free neutron stored in very small traps