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The free neutron has a mass of 939 565 413.3 eV/c 2, or 939.565 4133 MeV/c 2. This mass is equal to 1.674 927 471 × 10 −27 kg, or 1.008 664 915 88 Da. [4] The neutron has a mean-square radius of about 0.8 × 10 −15 m, or 0.8 fm, [20] and it is a spin-½ fermion. [21] The neutron has no measurable electric charge.
Its size is approximately 10 −15 meters and its density 10 18 kg/m 3. The descriptive term nuclear density is also applied to situations where similarly high densities occur, such as within neutron stars. Using deep inelastic scattering, it has been estimated that the "size" of an electron, if it is not a point particle, must be less than 10 ...
The neutrino [a] was postulated first by Wolfgang Pauli in 1930 to explain how beta decay could conserve energy, momentum, and angular momentum ().In contrast to Niels Bohr, who proposed a statistical version of the conservation laws to explain the observed continuous energy spectra in beta decay, Pauli hypothesized an undetected particle that he called a "neutron", using the same -on ending ...
The proton and neutron have nearly the same mass (938 MeV), [16] and may be regarded as one particle, the nucleon N(938),with two different charge states (proton +1, and neutron 0). [17] The proton's N (938) ground state and ∆ + (1232) excited state have different shapes. [ 18 ]
The neutron has a positively charged core of radius ≈ 0.3 fm surrounded by a compensating negative charge of radius between 0.3 fm and 2 fm. The proton has an approximately exponentially decaying positive charge distribution with a mean square radius of about 0.8 fm. [15]
Neutrons have no electrical charge and have a mass of 1.6749 × 10 −27 kg. [ 37 ] [ 38 ] Neutrons are the heaviest of the three constituent particles, but their mass can be reduced by the nuclear binding energy .
An up quark has electric charge + + 2 / 3 e, and a down quark has charge − + 1 / 3 e, so the summed electric charges of proton and neutron are +e and 0, respectively. [a] Thus, the neutron has a charge of 0 (zero), and therefore is electrically neutral; indeed, the term "neutron" comes from the fact that a neutron is ...
It does not ionize atoms in the same way that charged particles such as protons and electrons do (exciting an electron), because neutrons have no charge. However, neutron interactions are largely ionizing, for example when neutron absorption results in gamma emission and the gamma ray (photon) subsequently removes an electron from an atom, or a ...