Stellar collision triggers supernova explosion

Astronomers have found dramatic evidence that a black hole or neutron star spiraled its way into the core of a companion star and caused that companion to explode as a supernova. The astronomers were tipped off by data from ...

Photovoltaic perovskites can detect neutrons

A simple and cheap device for detecting neutrons has been developed by a team of EPFL researchers and their collaborators. The device, based on a special class of crystalline compounds called perovskites, could be used to ...

Nature of fast radio bursts clarified

By connecting two of the biggest radio telescopes in the world, astronomers have discovered that a simple binary wind cannot cause the puzzling periodicity of a fast radio burst after all. The bursts may come from a highly ...

Lasers light up neutron generation for radiography

Getting snapshots of systems and processes at precise time points is important to research and development in many fields, including biology, materials science, and engineering. Firing a neutron beam at a material is one ...


The neutron is a subatomic particle with no net electric charge and a mass slightly larger than that of a proton.

Neutrons are usually found in atomic nuclei. The nuclei of most atoms consist of protons and neutrons, which are therefore collectively referred to as nucleons. The number of protons in a nucleus is the atomic number and defines the type of element the atom forms. The number of neutrons determines the isotope of an element. For example, the carbon-12 isotope has 6 protons and 6 neutrons, while the carbon-14 isotope has 6 protons and 8 neutrons.

While bound neutrons in stable nuclei are stable, free neutrons are unstable; they undergo beta decay with a lifetime of just under 15 minutes (885.7 ± 0.8 s). Free neutrons are produced in nuclear fission and fusion. Dedicated neutron sources like research reactors and spallation sources produce free neutrons for the use in irradiation and in neutron scattering experiments.

Even though it is not a chemical element, the free neutron is sometimes included in tables of nuclides. It is then considered to have an atomic number of zero and a mass number of one.

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