Toru Moriya

New Result in the Production and Decay of an Isotope, 278113, of the 113th Element

An isotope of the 113th element, i.e., 278 113, was produced in a nuclear reaction with a 70 Zn beam on a 209 Bi target. We observed six consecutive α-decays following the implantation of a heavy particle in nearly the same position in the semiconductor detector under an extremely low background condition. The fifth and sixth decays are fully consistent with the sequential decays of 262 Db and 258 Lr in both decay energies and decay times. This indicates that the present decay chain consisted of 278 113, 274 Rg ( Z =111), 270 Mt ( Z =109), 266 Bh ( Z =107), 262 Db ( Z =105), and 258 Lr ( Z =103) with firm connections. This result, together with previously reported results from 2004 and 2007, conclusively leads to the unambiguous production and identification of the isotope 278 113 of the 113th element.

New result on the production of 277Cn by the 208Pb + 70Zn Reaction

The production and decay properties of an isotope of the 112th element, 277Cn, were investigated using a gas-filled recoil ion separator by irradiation of 208Pb targets with 70Zn beams at 347.5, 351.5, and 355.5 MeV. The excitation function for this reaction was measured for the first time. We observed one decay event assigned to the decay of 277Cn at the beam energy of 351.5 MeV. The measured production cross section was 0.078+0.179 pb. The present result gives improved half-lives of 0.61+0.46 and 0.19+0.14 ms for 277Cn and 273Ds, respectively. At the other energies, no event was observed. The measured upper cross section limits were 0.25 and 0.15 pb at the beam energies of 347.5 and 355.5 MeV, respectively.