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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 .
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.
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 .
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 .
Part of the Chart of Nuclides showing some stable or nearly-stable s-, r-, and p-nuclei. The classical, ground-breaking works of Burbidge, Burbidge, Fowler and Hoyle (1957) [1] and of A. G. W. Cameron (1957) [2] showed how the majority of naturally occurring nuclides beyond the element iron can be made in two kinds of neutron capture processes, the s- and the r-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]
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.
Plutonium-241 (241 Pu or Pu-241) is an isotope of plutonium formed when plutonium-240 captures a neutron.Like some other plutonium isotopes (especially 239 Pu), 241 Pu is fissile, with a neutron absorption cross section about one-third greater than that of 239 Pu, and a similar probability of fissioning on neutron absorption, around 73%.