Superheavy research at RIKEN

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 α decay chains connected into the previously known decay of ²⁶⁶Bh and ²⁶²Db via previously unknown α decays of ²⁷⁸113, ²⁷⁴Rg and ²⁷⁰Mt.