R-process in neutrino-driven winds

This thesis considers the neutrino-driven wind that arises from a proto-neutron star following a supernova explosion as a possible site for the synthesis of the heavy elements by the r-process. We first review the conditions necessary to obtain an r-process, the constraints on the r-process yields for each event, and show the neutrino-driven winds from proto-neutron stars are suitable for an r-process. We next discuss some of the modifications of the supernova code that were necessary in order to numerically simulate the neutrino-driven winds and steps necessary to initiate these conditions. Three important parameters of the wind characterizing the nucleosynthesis are the net electron fraction, the entropy per baryon, and the expansion time-scale. We derive approximate analytic expressions for the neutrino luminosities and mean energies, and the final entropy and net electron fraction of the wind, and compare those against a numerical simulation. We finally present the results of a numerical simulation of the first several seconds of the wind phase, and conclude with an assessment of whether or not an r-process will occur at this time.