Neutron-deficient superheavy nuclei obtained in the 240Pu+48Ca reaction

We present new results from investigations of the ²⁴⁰Pu+⁴⁸Ca reaction at a projectile energy of 250 MeV. Three new decay chains of ²⁸⁵Fl were detected with decay properties mostly consistent with those measured in earlier studies. An additional chain was observed where the nuclei may decay through energy levels different from those of the other six chains registered so far. The cross section of the ²⁴⁰Pu(⁴⁸Ca,3 n )²⁸⁵Fl reaction was measured to be 0 .58_-0.33^+0.60pb , which is a factor of about 4-5 lower than that measured in the previous experiment at 245 MeV beam energy [V. K. Utyonkov et al., Phys. Rev. C 92, 034609 (2015)., 10.1103/PhysRevC.92.034609], consistent with expectations. The origin of an additional chain consisting of a recoil, α particle, and fission event is analyzed. The assignment of 25 short-lived SF events observed in this experiment is also discussed.