Speaker
Description
The $^{232}$Th + $^{48}$Ca and $^{238}$U + $^{40}$Ar reactions have been studied at the gas-filled separator DGFRS-2 at the Superheavy Element Factory at Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research. Three new nuclides were synthesized for the first time: a spontaneously fissioning (SF) $^{268}$Sg with the half-life T$_{SF}$ = 13$^{+17}_{−4}$ s; an α decaying $^{272}$Hs with T$_{α}$ = 0.16$^{+0.19}_{-0.06}$ s and E$_{α}$ = 9.63 ± 0.02 MeV; and $^{276}$Ds with T$_{1/2}$ = 0.15$^{+0.10}_{-0.04}$ ms, E$_{α}$ = 10.75 ± 0.03 MeV, and an SF branch of 57%. For the first time, in 5n-evaporation channel a new isotope $^{275}$Ds with a half-life of 0.43$^{+0.29}_{-0.12}$ ms and α-particle energy of 11.20 ± 0.02 MeV was synthesized in the $^{48}$Ca-induced reaction with the actinide nucleus and identified by measuring correlated α decays ending in known nuclei. The decay properties of these nuclei are in agreement with the systematics of experimental partial half-lives and α-decay energies of heavy known nuclei, as well as spontaneous-fission half-lives. The cross sections of the 4n-evaporation channel of 0.07$^{+0.17}_{−0.06}$ pb, 0.7$^{+1.1}_{-0.5}$ pb, and 0.11$^{+0.46}_{-0.09}$ pb were measured at 231, 238, and 251 MeV, respectively. The cross sections of the $^{232}$Th($^{48}$Ca, 5n)$^{275}$Ds reaction of 0.11$^{+0.46}_{−0.09}$ and 0.34$^{+0.59}_{-0.16}$ pb were measured at excitation energies of the 280Ds compound nucleus E$^{∗}$ = 51 and 56 MeV, respectively. The cross section of the 5n-evaporation channel of the $^{238}$U + $^{40}$Ar reaction at E$^{∗}$ = 49 MeV of 0.18$^{+0.44}_{−0.12}$ pb turned out to be comparable to that for $^{275}$Ds at close excitation energy.
| Section | Nuclear physics (Section 1) |
|---|
