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, (277)112, and on that of the 113th element (278)113, are reviewed. Tow decay chains which are assigned to be ones originating from the isotope (277)112 were observed in the Pb-201(Zn-70, 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 (277)112 reported by a research group at Gesellschaft fur 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 Bi-209(Zn-70, n). Those are assigned to be the convincing candidate events of the decays of the isotope of the 113th element (278)113, and its daughter nuclei, (274)Rg, (270)Mt, (266)Bh, and (262)Db.