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Neutron capture is a nuclear reaction in which an atomic nucleus and one or more neutrons collide and merge to form a heavier nucleus. [1] Since neutrons have no electric charge, they can enter a nucleus more easily than positively charged protons , which are repelled electrostatically .
Neutron capture nucleosynthesis describes two nucleosynthesis pathways: the r-process and the s-process, for rapid and slow neutron captures, respectively. R-process describes neutron capture in a region of high neutron flux , such as during supernova nucleosynthesis after core-collapse, and yields neutron-rich nuclides .
Neutron capture therapy was first proposed in the literature in 1936 by Gordon L. Locher, who observed that isotopes with large neutron capture cross sections, such as boron-10, could be accumulated in cancerous tissue and bombarded with thermal neutrons to induce destruction of the cancerous cells. [4]
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 by the p-process and s-process.
An example of a nucleogenic nuclide is neon-21 produced from neon-20 that absorbs a thermal neutron (though some neon-21 is also primordial). [1] Other nucleogenic reactions that produce heavy neon isotopes are (fast neutron capture, alpha emission) reactions, starting with magnesium-24 and magnesium-25, respectively. [2]
The boundaries of this valley are the neutron drip line on the neutron-rich side, and the proton drip line on the proton-rich side. [2] These limits exist because of particle decay, whereby an exothermic nuclear transition can occur by the emission of one or more nucleons (not to be confused with particle decay in particle physics).
The term p-process (p for proton) is used in two ways in the scientific literature concerning the astrophysical origin of the elements (nucleosynthesis).Originally it referred to a proton capture process which was proposed to be the source of certain, naturally occurring, neutron-deficient isotopes of the elements from selenium to mercury.
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