Isotopic Spin

isospin

 or isobaric spin or isotopic spin

Property characteristic of families of related subatomic particles differing mainly in the values of their electric charge. The families are known as isospin multiplets. The components of atomic nuclei, the neutron and the proton, form an isospin doublet since they differ only in electric charge and subsidiary properties. They are considered different versions of the same object, called a nucleon. The isospin of a nucleon has a value of ¹⁄₂.

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isotopic spin [¦ī·sə¦täp·ik ′spin]

(nuclear physics)

A quantum-mechanical variable, resembling the angular momentum vector in algebraic structure whose third component distinguished between members of groups of elementary particles, such as the nucleons, which apparently behave in the same way with respect to strong nuclear forces, but have different charges. Also known as isobaric spin; isospin; i-spin.

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Isotopic Spin 

one of the characteristics of strongly interacting particles that determines (together with other characteristics—mass, spin, and baryon charge) whether or not the particle belongs to a group of particles with similar properties (but with different electric charges) that participate identically in strong interactions. (See ISOTOPIC INVARIANCE.)