An Etymological Dictionary of Astronomy and Astrophysics

A quantity used to describe a → radionuclide that has more than one → decay mode.
For a particular decay mode, the ratio of the number of atoms decaying by that decay mode to the number decaying in total:

BR_i = k_i/(k₁ + k₂ + …) = k_i/k, where k is → decay constant.

See also: → branching; → ratio.