S-process

The s-process or slow-neutron-capture-process is a nucleosynthesis process that occurs at relatively low neutron density and intermediate temperature conditions in stars. Under these conditions the rate of neutron capture by atomic nuclei is slow relative to the rate of radioactive beta-minus decay. In the S-process, a stable isotope captures a neutron, but the radioactive isotope that results decays to its stable daughter before the next neutron is captured. This process produces stable isotopes by moving along the valley of beta-decay stable isobars in the chart of isotopes. The S-process produces approximately half of the isotopes of the elements heavier than iron, and therefore plays an important role in the galactic chemical evolution. The S-process differs from the more rapid R-process of neutron capture by its slow rate of neutron captures.