[en] A joint working party of the IUPAC and IUPAP has recommended that the RIKEN research group be given recognition for the discovery of the element 113. Three decay chains originated from ²⁷⁸113 were observed by using ²⁰⁹Bi(⁷⁰Zn,n)²⁷⁸113 reaction. The first and second decay chains consist of four alpha decays and ended by spontaneous fission of ²⁶²Db. The third chain consists of six alpha decays connected to the ²⁵⁴Md. Those decay properties are consistent with known properties of ²⁶⁶Bh, ²⁶²Db and ²⁵⁸Lr. The experimental method and results are described in this report. (author)

[en] Decay properties of an isotope ²⁶⁶Bh and its daughter nucleus ²⁶²Db produced by the ²⁴⁸Cm(²³Na,5n) reaction were studied by using a gas-filled recoil separator coupled with a position-sensitive semiconductor detector. ²⁶⁶Bh was clearly identified from the correlation of the known nuclide, ²⁶²Db. The obtained decay properties of ²⁶⁶Bh and ²⁶²Db are consistent with those observed in the ²⁷⁸113 chain, which provided further confirmation of the discovery of ²⁷⁸113. (author)

[en] 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.

[en] Decay properties of an isotope ²⁶⁶Bh and its daughter nucleus ²⁶²Db produced by the ²⁴⁸Cm(²³Na,5n) reaction were studied by using a gas-filled recoil separator coupled with a position-sensitive semiconductor detector. ²⁶⁶Bh was clearly identified from the correlation of the known nuclide, ²⁶²Db. The obtained decay properties of ²⁶⁶Bh and ²⁶²Db are consistent with those observed in the ²⁷⁸113 chain by RIKEN collaboration, which provided further confirmation of the discovery of ²⁷⁸113.

[en] 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 fuer 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

No abstract available

[en] An isotope of the 113th element, i.e., ²⁷⁸113, was produced in a nuclear reaction with a ⁷⁰Zn beam on a ²⁰⁹Bi target. We observed six consecutive α-decays following the implantation of a heavy particle in nearly the same position in the semiconductor detector under an extremely low background condition. The fifth and sixth decays are fully consistent with the sequential decays of ²⁶²Db and ²⁵⁸Lr in both decay energies and decay times. This indicates that the present decay chain consisted of ²⁷⁸113, ²⁷⁴Rg (Z=111), ²⁷⁰Mt (Z=109), ²⁶⁶Bh (Z=107), ²⁶²Db (Z=105), and ²⁵⁸Lr (Z=103) with firm connections. This result, together with previously reported results from 2004 and 2007, conclusively leads to the unambiguous production and identification of the isotope ²⁷⁸113 of the 113th element. (author)

[en] The convincing candidate event of the isotope of the 113th element, were observed, for the first time, in the ²⁰⁹Bi+⁷⁰Zn reaction at a beam energy of 349.0 MeV with a total dose of 1.7 x 1019. Alpha decay energies and decay times of the candidates, ²⁷⁸113, ²⁷⁴111, and ²⁷⁰Mt, were (11.68±0.04 MeV, 0.344 ms), (11.15±0.07 MeV, 9.26 ms), and (10.03±0.07 MeV, 7.16 ms), respectively. The production cross section of the isotope was deduced to be 55_-45⁺¹⁵⁰ fb(10^-39 cm²). The experiment was performed at RIIKEN (The Institute of Physical and Chemical Research) Linear Accelerator (RILAC) Facility. The evaporation residues produced by the reaction with a ⁷⁰Zn beam provided by the RILAC and the bismuth targets, were separated by a gas-filled recoil separator (GARIS) from the beam particles and the target recoils, and collected at the focus of GARIS. We observed an event of implantation of an evaporation residue in the position-sensitive semiconductor detector followed by four consecutive alpha decays terminated by a spontaneous fission decay. Assignment of the event was based on genetic correlation of sequential alpha decays to the already known nuclides ²⁶⁶Bh and ²⁶²Db. The fourth alpha decay and the following spontaneous fission decay were assigned to be the decays of ²⁶⁶Bh and ²⁶²Db, respectively because of agreements of decay energies and decay times with the reported values. As a consequence, the preceding three alpha decays were assigned to be ones of ²⁷⁸113, ²⁷⁴111, and ²⁷⁰Mt.

[en] The isotope of ²⁶⁶Bh was produced and identified definitely in bombardments of ²⁴³Am target with 162 MeV ²⁶Mg ions at HIRFL. Identification was made by observation of correlated α-particle decays between the Bh isotopes and their Db and Lr daughters using a rotating wheel system. The measured α energy for ²⁶⁶Bh is (9.03 ± 0.08) MeV, and this value close to the 9.07 MeV for ²⁶⁶Bh observed in the first chain of element 113 at RIKEN. The half-life of ²⁶⁶Bh is (0.66)_-0.26^+0.59s. The Q_α value derived from this experiment fits well into the general trend in a 'Q_α-N systematics' for the isotopes with Z=107. (authors)

[en] 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 fuer 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