Superheavy research in Japan

At RIKEN (The Institute of Physical and Chemical Research) in Japan, we have performed experiments to study the productions and decays of the heaviest elements produced by one-neutron emission channels of 208Pb and 209Bi based heavy-ion-induced fusion reactions. A gas-filled-type recoil separator has been used for collecting evaporation residues of the reactions separating them from high intensity beam particles. The reactions studied were 208Pb(58Fe,n)265Hs, 208Pb(64Ni,n)271Ds, 209Bi(64Ni,n)272Rg, 208Pb(70Zn, n) 277112, and 209Bi(70Zn,n)278113. In studies of the first four reactions we have provided the independent confirmations of the productions and their decays of the isotopes, 265Hs, 271Ds, 272Rg, and 277112, as well as the decay properties of their decay daughters, previously studied by Hofmann et al., a group of Gesellschaft für Schwerionenforschung (GSI), Germany. In the last reaction, we observed two decay chains originated from the isotope 278113, assigned firstly by generic correlation of the alpha decay chains connected into the previously known decay of 266Bh and 262Db via previously unknown alpha decays of 278113, 274Rg and 270Mt.