Conditions required for the r-process

The astrophysical site for the production of the r-process nuclei is not presently known. Part of the reason for this lack of knowledge is that the range of conditions which enable the production of these nuclei has not been accurately determined. Dynamic r-process nucleosynthesis calculations provide a means by which limits can be placed on the range of initial conditions that can produce r-process nuclei. Such calculations have several important time scales inherent to them. By requiring the time scales for neutron captures, β-decays, hydrodynamic expansion, and seed-nucleus production to be mutually compatible, it has been found that constraints can be placed on the initial temperatures, densities, neutron/proton ratios, and chemical compositions that can produce the r-process nuclei. The allowed ranges of these parameters are presented along with the results of r-process calculations performed for several different sets of initial conditions