The r-process ("r" for "rapid") is the creation of elements heavier than zinc through the intense bombardment of other elements by neutrons.
It occurs on a timescale so short compared
to the time needed for nuclear decay via the emission of a beta
particle that it enables chains of reactions involving highly unstable
intermediate nuclei to take place. It is believed to occur in supernovae,
which unleash a fierce flux of neutrons, and to be responsible for the manufacture
of most of the elements in the periodic
table more massive than iron.