Superheavy research at RIKEN

At RIKEN, Japan, we performed experiments to study the productions and decays of the heaviest elements produced by ²⁰⁸Pb- and ²⁰⁹Bi- based 'cold fusion' reactions. A gas-filled recoil separator GARIS was used for the study. In the study of ²⁰⁹Bi(⁷⁰Zn, n) reaction, we observed two decay chains originating from an isotope of the 113th element, ¹⁷⁸113, which were 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. In addition, decay properties of an isotope ²⁶⁶Bh and its daughter nucleus ²⁶²Db produced by the ²⁴⁸Cm(²³Na, 5n) reaction were studied. ²⁶⁶Bh was clearly identified from the correlation of the known nuclide, ²⁶²Db, providing further confirmation of the discovery of ²⁷⁸113.