Experiments using a ${}^{48}\mathrm{Ca}$ beam on ${}^{238}\mathrm{U}$ and ${}^{242}\mathrm{Pu}$ targets to produce superheavy nuclei were performed at the gas-filled separator DGFRS-2 online to the new cyclotron DC280 at the SHE Factory at JINR. The decay properties of ${}^{286}\mathrm{Fl}$ and ${}^{287}\mathrm{Fl}$, as well as their α-decay products, were refined after the detection of 25 and 69 new decay chains, respectively. In addition, 16 decay chains of ${}^{283}\mathrm{Cn}$ were observed in the ${}^{238}\mathrm{U}+{}^{48}\mathrm{Ca}$ reaction. The possibility of existing of isomeric states in the ${}^{287}\mathrm{Fl}$ consecutive α decays is discussed. A new α line with an energy of 100?200 keV lower than the main one at 10.19 MeV was observed for the first time for even-even ${}^{286}\mathrm{Fl}$ decay. A maximum cross section of $10.4_{?2.1}^{+3.5}\mathrm{pb}$ was measured for the ${}^{242}\mathrm{Pu}\left({}^{48}\mathrm{Ca},3n\right) {}^{287}\mathrm{Fl}$ reaction.

• Received 25 May 2022
• Accepted 1 August 2022

DOI: https://doi.org/10.1103/PhysRevC.106.024612