Abstract
In this paper, we present results of the second experiment on the synthesis of Mc isotopes in the 243Am+48Ca reaction performed at the gas-filled separator DGFRS-2 of the SHE Factory at JINR. The new isotope 286Mc was synthesized, and its half-life of 20+98−9 ms and α-particle energy of 10.71±0.02 MeV were determined. A 286Mc α−decay chain was recorded down to the spontaneous fission of 266Db. The spontaneous fission of 279Rg was observed for the first time in one of four new decay chains of 287Mc. The excitation function of the reaction was measured at three 48Ca energies of 242, 250, and 259 MeV; the latter resulted in the first observation of the 5n−evaporation channel with a cross section of 0.5+1.3−0.4 pb. The decay properties of 21 previously known odd−Z isotopes were improved. The potential for an electron-capture decay mode is discussed for 288Mc and 284Nh isotopes. The half-lives of spontaneously fissioning nuclei produced in the 48Ca−induced reactions with actinide targets are compared with several theoretical predictions.
