Exploring the decay probability of neutron-rich superheavy nuclei

The modes of decay for the even-even isotopes of superheavy nuclei of Z = 118 and 120 with neutron number $160\le N\le 204$ are investigated in the framework of the axially deformed relativistic mean field model. The asymmetry parameter $\eta$ and the relative neutron-proton asymmetry of the surface to the center ($R_{\eta }$) are estimated for the ground state density distributions of the nuclei. We suggest that the resulting asymmetry parameter $\eta$ and the relative neutron-proton asymmetry $R_{\eta }$ of the density play a crucial role in the preformation factor of the decay half life.