n.
Amount of angular momentum associated with a subatomic particle or nucleus .
It is measured in multiples of 0127; (h-bar), equal to Planck's constant divided by 2 03C0; . Electrons , neutrons , and protons have a spin of 1 2 , for example, while pions and helium nuclei have zero spin. The spin of a complex nucleus is the vector sum of the orbital angular momentum and intrinsic spins of the constituent nucleons. For nuclei of even mass number, the multiple is an integral; for those of odd mass number, it is a half-integer. See also Bose-Einstein statistics , Fermi-Dirac statistics .