First experiment at the Super Heavy Element Factory: High cross section of 288Mc in the 243Am+48Ca reaction and identification of the new isotope 264Lr

Abstract

We present results of the first experiment aimed at the synthesis of Mc isotopes in the 243Am+48Ca reaction performed at the new gas-filled separator DGFRS-2 online to the new cyclotron DC280 at the Super Heavy Element Factory at JINR. Fifty-five new decay chains of 288Mc and six chains assigned to 289Mc were detected. The α decay of 268Db with an energy of 7.6–8.0 MeV, half-life of 16+6−4h, and a branch of 55+20−15% was registered for the first time, and a new spontaneously fissioning isotope 264Lr with a half-life of 4.9+2.1−1.3h was identified. The cross section for the 243Am(48Ca,3n)288Mc reaction was measured to be 17.1+6.3−4.7 pb, which is the largest value for the known superheavy nuclei at the island of stability.