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The first step of the proton-proton chain is a two-stage process: first, two protons fuse to form a diproton: 1 H + 1 H + 1.25 MeV → 2 He; then the diproton immediately beta-plus decays into deuterium: 2 He → 2 H + e + + ν e + 1.67 MeV; with the overall formula 1 H + 1 H → 2 H + e + + ν e + 0.42 MeV.
It is the reaction which occurs when a neutron enters a nucleus and a proton leaves the nucleus simultaneously. [1] For example, sulfur-32 (32 S) undergoes an (n,p) nuclear reaction when bombarded with neutrons, thus forming phosphorus-32 (32 P). The nuclide nitrogen-14 (14 N) can also undergo an (n,p) nuclear reaction to produce carbon-14 (14 C).
Protein folding problem: Is it possible to predict the secondary, tertiary and quaternary structure of a polypeptide sequence based solely on the sequence and environmental information? Inverse protein-folding problem: Is it possible to design a polypeptide sequence which will adopt a given structure under certain environmental conditions?
A fixed source calculation involves imposing a known neutron source on a medium and determining the resulting neutron distribution throughout the problem. This type of problem is particularly useful for shielding calculations, where a designer would like to minimize the neutron dose outside of a shield while using the least amount of shielding ...
A neutron in free state is an unstable particle, with a half-life around ten minutes. It undergoes β − decay (a type of radioactive decay) by turning into a proton while emitting an electron and an electron antineutrino. This reaction can occur because the mass of the neutron is slightly greater than that of the proton.
An animation of the strong interaction between a proton and a neutron, mediated by pions. The colored small double circles inside are gluons . In nuclear physics and particle physics , the strong interaction , also called the strong force or strong nuclear force , is a fundamental interaction that confines quarks into protons , neutrons , and ...
The boundaries of the valley of stability, that is, the upper limits of the valley walls, are the neutron drip line on the neutron-rich side, and the proton drip line on the proton-rich side. The nucleon drip lines are at the extremes of the neutron-proton ratio. At neutron–proton ratios beyond the drip lines, no nuclei can exist.
The liquid drop model is one of the first models of nuclear structure, proposed by Carl Friedrich von Weizsäcker in 1935. [5] It describes the nucleus as a semiclassical fluid made up of neutrons and protons, with an internal repulsive electrostatic force proportional to the number of protons.