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The magnetic moment of the neutron is an indication of its quark substructure and internal charge distribution. [85] In the quark model for hadrons, the neutron is composed of one up quark (charge +2/3 e) and two down quarks (charge −1/3 e). [85]
The rms charge radius is a measure of the size of an atomic nucleus, particularly the proton distribution. The proton radius is about one femtometre = 10 −15 metre. It can be measured by the scattering of electrons by the nucleus. Relative changes in the mean squared nuclear charge distribution can be precisely measured with atomic spectroscopy.
In 1949, D. Hughes and M. Burgy measured neutrons reflected from a ferromagnetic mirror and found that the angular distribution of the reflections was consistent with spin 1 / 2 . [48] In 1954, J. Sherwood, T. Stephenson, and S. Bernstein employed neutrons in a Stern–Gerlach experiment that used a magnetic field to separate the neutron ...
The proton's RMS charge radius of 0.8414 fm only defines the spatial extent of its charge distribution, i.e. the distance from its center of mass to its farthest point. Examination of the angular dependence of the charge distribution indicates that the proton is not a perfect sphere.
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]
decay generally occurs in neutron-rich nuclei. [24] The generic equation is: A Z X → A Z+1 X′ + e − + ν e [1] where A and Z are the mass number and atomic number of the decaying nucleus, and X and X′ are the initial and final elements, respectively. Another example is when the free neutron (1 0 n) decays by β − decay into a proton ...
Nuclear reactions may be shown in a form similar to chemical equations, for which invariant mass must balance for each side of the equation, and in which transformations of particles must follow certain conservation laws, such as conservation of charge and baryon number (total atomic mass number). An example of this notation follows:
Quantity (common name/s) (Common) symbol/s Defining equation SI units Dimension Number of atoms N = Number of atoms remaining at time t. N 0 = Initial number of atoms at time t = 0