Properties of the superheavy element 287115 and its α-decay time

The properties of nuclei belonging to the newly observed α-decay chain starting from 287115 have been studied. The axially deformed relativistic mean field calculation with the force NL-Z2 has been performed in the blocked BCS approximation. Some ground state properties such as average binding energies, deformations, spins, and parities as well as Q values of the α decay for this decay chain have been calculated and compared with known experimental data. Good agreement is found. The study of the single-particle spectrum in 287115 shows that after Z=100 the magic numbers appear at Z=116,114 and smaller gaps at Z=(110),(106) and (122),(126),(128). For neutrons, the gaps appear at N=174,(172),(168),(162),(160),(186). Because of the neutron-deficient character of superheavy nuclei, there is some probability that protons could be distributed at positive levels, which form the resonance continuum; this is worth further investigation. The α-decay lifetimes in the 287115 decay chain are evaluated by different formulas and compared with experimental data. The methods that give better agreement with the data are selected