The Astrophysical Site of the r-process

Over half the heavy elements with mass number A $>$ 100 are made by rapid neutron capture. However, the astrophysical site of this element synthesis is not yet known. There are a few sites under consideration, including core collapse supernovae, gamma ray bursts and neutron star mergers. I will discuss the prospects for obtaining an r-process in these cases, as well as the roles played by neutrinos and fission cycling.