Influence of spontaneous fission rates on the yields of superheavy elements in the r-process

The formation of heavy elements in the neutron star merger scenario is considered. In such a scenario, the duration of the r-process is long and when the nucleosynthesis wave passes through the region of actinides, beta-delayed, neutron-induced, and spontaneous fission are added to the main r-process reaction channels. The dependence of the formation of superheavy elements on spontaneous fission model is investigated numerically. The formation of nuclei lighter than the cadmium-peak elements and cosmochronometer nuclei is shown to depend on strongly on the spontaneous fission model used in nucleosynthesis calculations. The regions of nuclei with short spontaneous fission half-lives prevent the formation of superheavy elements in the r-process, but the prediction of their yields is so far inaccurate because of an insufficient accuracy of calculating a number of transactinide parameters. The relative contributions from neutron-induced, beta-delayed, and spontaneous fission have been determined for various spontaneous fission models in the nucleosynthesis scenario considered.