Study of Neutron-Deficient Nuclei in the 239,240Pu+48Ca Reactions
Three new decay chains of 285Fl were observed in the 3n-evaporation channel of the 240Pu + 48Ca reaction [1]. The irradiation was performed at the Dubna Gas Filled Recoil Separator (DGFRS) and using 250 MeV 48Ca beam accelerated at the U400 cyclotron of the Flerov Laboratory of Nuclear Reactions, JINR. The decay properties of the observed nuclei are mostly in agreement with a chain identified at the BGS in the 242Pu(48Ca,5n) reaction [2] and three chain previously observed at the DGFRS in the same 240Pu(48Ca,3n) reaction at lower energy of 245 MeV [3]. The lifetime of 269Sg observed in one chain exceeds that derived from other five decays by a factor of 33, which might indicate the observation of transitions through different levels in 285Fl and descendants. The cross section of the reaction was measured to be 0.58+0.60−0.33 pb, which is lower by a factor of 4-5 than the value measured at 245 MeV 48Ca and is in agreement with expectations for the 3n-evaporation channel.
