Experiments on synthesis of the heaviest element at RIKEN

At the Institute of Physical and Chemical Research (RIKEN) a series of experiments studying the productions and their decays of the heaviest elements have been performed by using a gas-filled recoil ion separator GARIS. Results on the isotope of the 112th element, ²⁷⁷112, and on that of the 113th element, ²⁷⁸113, are reviewed. Tow decay chains which are assigned to be ones originating from the isotope ²⁷⁷112 were observed in the ²⁰⁸Pb(⁷⁰Zn, n) reaction. Both chains consisted of four consecutive alpha decays followed by a spontaneous fission. The results provide a confirmation of the production and decay of the isotope ²⁷⁷112 reported by a research group at Gesellschaft für Schwerionenforschung (GSI), Germany, produced via the same reaction by using a velocity filter. Tow decay chains, both consisted of four consecutive alpha decays followed by a spontaneous fission, were observed also in the reaction ²⁰⁹Bi( ⁷⁰Zn, n). Those are assigned to be the convincing candidate events of the decays of the isotope of the 113th element, ²⁷⁸113, and its daughter nuclei, ²⁷⁴Rg, ²⁷⁰Mt, ²⁶⁶Bh, and ²⁶²Db.