High Quality Content by WIKIPEDIA articles! The r-process is a nucleosynthesis process, likely occurring in core-collapse supernovae (see also supernova nucleosynthesis) responsible for the creation of approximately half of the neutron-rich atomic nuclei that are heavier than iron. The process entails a succession of rapid neutron captures on seed nuclei, typically Ni-56, hence the name r-process. The other predominant mechanism for the production of heavy elements is the s-process, which is nucleosynthesis by means of slow neutron captures, primarily occurring in AGB stars, and together these two processes account for a majority of galactic chemical evolution of elements heavier than iron.