Neutrons Definition and 10 Discussions

The neutron is a subatomic particle, symbol n or n0, which has a neutral (not positive or negative) charge, and a mass slightly greater than that of a proton. Protons and neutrons constitute the nuclei of atoms. Since protons and neutrons behave similarly within the nucleus, and each has a mass of approximately one atomic mass unit, they are both referred to as nucleons. Their properties and interactions are described by nuclear physics.
The chemical properties of an atom are mostly determined by the configuration of electrons that orbit the atom's heavy nucleus. The electron configuration is determined by the charge of the nucleus, which is determined by the number of protons, or atomic number. The number of neutrons is the neutron number. Neutrons do not affect the electron configuration, but the sum of atomic and neutron numbers is the mass of the nucleus.
Atoms of a chemical element that differ only in neutron number are called isotopes. For example, carbon, with atomic number 6, has an abundant isotope carbon-12 with 6 neutrons and a rare isotope carbon-13 with 7 neutrons. Some elements occur in nature with only one stable isotope, such as fluorine. Other elements occur with many stable isotopes, such as tin with ten stable isotopes.
The properties of an atomic nucleus depend on both atomic and neutron numbers. With their positive charge, the protons within the nucleus are repelled by the long-range electromagnetic force, but the much stronger, but short-range, nuclear force binds the nucleons closely together. Neutrons are required for the stability of nuclei, with the exception of the single-proton hydrogen nucleus. Neutrons are produced copiously in nuclear fission and fusion. They are a primary contributor to the nucleosynthesis of chemical elements within stars through fission, fusion, and neutron capture processes.
The neutron is essential to the production of nuclear power. In the decade after the neutron was discovered by James Chadwick in 1932, neutrons were used to induce many different types of nuclear transmutations. With the discovery of nuclear fission in 1938, it was quickly realized that, if a fission event produced neutrons, each of these neutrons might cause further fission events, in a cascade known as a nuclear chain reaction. These events and findings led to the first self-sustaining nuclear reactor (Chicago Pile-1, 1942) and the first nuclear weapon (Trinity, 1945).
Free neutrons, while not directly ionizing atoms, cause ionizing radiation. So they can be a biological hazard, depending on dose. A small natural "neutron background" flux of free neutrons exists on Earth, caused by cosmic ray showers, and by the natural radioactivity of spontaneously fissionable elements in the Earth's crust. Dedicated neutron sources like neutron generators, research reactors and spallation sources produce free neutrons for use in irradiation and in neutron scattering experiments.

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  1. R

    A Need help with the reaction of neutrons and electrons

    Please let me know if the following reaction is possible for high energy electrons colliding with neutrons or neutron-rich nuclei: n+e^{-}\to \Delta^{-}+\nu_e.\tag{1} If it is forbidden for some conservation law or for some other reason, please give me an explanation why. This reaction is...
  2. J

    I If we teleport 1mm^3 of a neutron star outside it what hapens?

    if we teleport a small amount of millimeter cube of a neutron star outside it, will it remain still as a very dense heavy neutron clump or will it revert back into its components (iron) or will the neutron destabilize and turn into cosmic radiation of neutrons which then turn back into hydrogen?
  3. O

    I Number of fission neutrons in ENSDF

    I use ENSDF to get information about gamma energies and emission abundances for various nuclides. Now I need to know data about Cf-252, in particular the abundance of spontaneous fission and the average number of emitted neutrons per fission. Where can I find this information there? Just as a...
  4. Pickled_Gorilla

    Neutrons Falling on a Detector

    Homework Statement A collection of neutrons, nominally at rest, are confined in a region 1.0 nm wide on the x-axis at a height of 50 cm above a neutron detector. The neutrons are released and fall under the influence of gravity towards the detector which records the horizontal position of the...
  5. gennarakis

    I Quantum Kinetic Energy of Neutrons, Protons and Electrons

    Hi there, I have a problem to solve in Cosmology which says: "Write the formulas for the quantum kinetic energy of neutrons, protons and electrons as well as the formula for the gravitational energy for a neutron star that is comprised of free neutrons, protons and electrons in a ratio of Nn ...
  6. P

    A Liquid Scintillation Counter using U-238 to detect neutrons

    I'm trying to make a LSC with U-238 (non-aqueous form) dipped in the scintillating cocktail to detect fast neutrons (no thermals or epithermals, only fast) from a Cf-252 source. How do I calculate the wavelength emerging from the cocktail (assuming U-238 does not react with the cocktail)? Also...
  7. G

    Fission reaction

    a certain fission reaction releases 3 neutrons. how many of these neutrons must go on to produce a subsequent fission if a chain reaction is to be sustained?
  8. O

    What happens to neutrons in plasma state?

    Let's say we have a mol of hellium-3 and we heat it up until it becomes plasma. What happens to the neutrons? Wikipedia does not mention anything about them. It only says that "Plasma is loosely described as an electrically neutral medium of unbound positive and negative particles". Just to...
  9. Phaeous

    Of Lost Neutrons Within Reactors

    How is a continuous chain reaction maintained within a moderator if it is not fissile material? Are the fissile materials mixed with the moderator or are they coalesced at the center of the surrounding moderator? If it is the latter, how would the surrounding moderator allow fissile material to...
  10. TerranIV

    Could Dark Matter be composed of neutrons?

    I was thinking about the properties of dark matter - how it doesn't seem to interact with any of the forces of the universe except gravity and I was thinking about how neutrinos also don't have any charge and they don't interact with any other forces except the weak force and gravity. I thought...