The astrophysical r-process and its dependence on properties of nuclei far from stability: beta strength functions and neutron capture rates

It is shown that the astrophysical r-process and the question of its site are very sensitive to 'standard' nuclear physics parameters like the beta decay properties and neutron capture rates. Since for these quantities in almost all r-process calculations up to now, and also in all estimates of the production rates of chronometric pairs, only very rough assumptions have been made, it is attempted to present procedures which put the calculation of these quantities for nuclei far from stability on a reliable physical basis. This is done by a microscopic description of the beta strength function and by using a statistical model based on a 'next to first principles' optical potential including effects of deformation for the neutron capture rates. The beta -decay rates for approximately 6000 nuclei between the beta -stability line and the neutron drip line are calculated. The heavy element synthesis by explosive He burning then is calculated using these beta -rates and using realistic star models treating the supernova explosion hydrodynamically. It is shown that-as a consequence of the revised beta -decay rates-explosive He burning seems at present to be the most convincing site of an r-process leading to a solar r-element distribution in one event. (77 refs).