Y. L. Zhao

Experiment on the Synthesis of Element 113 in the Reaction 209Bi(70Zn,n)278113

The convincing candidate event of the isotope of the 113th element, 278 113, and its daughter nuclei, 274 111 and 270 Mt, were observed, for the first time, in the 209 Bi + 70 Zn reaction at a beam energy of 349.0 MeV with a total dose of 1.7 ×10 19 . Alpha decay energies and decay times of the candidates, 278 113, 274 111, and 270 Mt, 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 +150 -45 fb (10 -39 cm 2 ).

Production and decay properties of 272111 and its daughter nuclei

The production and decay of 272 111 has been investigated using a gas-filled recoil ion separator in irradiations of 209 Bi targets with 64 Ni beam at 320, 323 and 326 MeV. We have observed 14 α-decay chains in total, that can be assigned, on the basis of their time correlations, to subsequent decays from 272 111 produced in the 209 Bi( 64 Ni,1n) reaction. The present result is the first clear confirmation for the discovery of 272 111 and its α-decay products, 264 Bh and 268 Mt, reported previously by a GSI group. New information on their half-lives and decay energies as well as the excitation function is presented.

Production and decay properties of

The production and decay of 272 111 has been investigated using a gas-filled recoil ion separator in irradiations of 209 Bi targets with 64 Ni beam at 320, 323 and 326 MeV. We have observed 14 α-decay chains in total, that can be assigned, on the basis of their time correlations, to subsequent decays from 272 111 produced in the 209 Bi( 64 Ni,1n) reaction. The present result is the first clear confirmation for the discovery of 272 111 and its α-decay products, 264 Bh and 268 Mt, reported previously by a GSI group. New information on their half-lives and decay energies as well as the excitation function is presented.

^{272}

A gas-filled type of recoil separator for heavy element research was installed at an experimental hall of RIKEN Linear Accelerator facility to realize getting higher intensity of primary beam and long beam time. Performance of the separator was studied using target recoils and various nuclear reactions. The results show the high performance of the separator for heave element research. As an application of the GARIS, production and identification of an isotope of the 110th element 271[110] have been performed using the 208Pb(64Ni,1n)271[110] reaction. Three decay chains coincide well both in decay times and energies with the ones reported by the group of SHIP experiment at GSI, Germany. Our results provide a confirmation of the synthesis of an isotope 271[110] of element 110.

111 and its daughter nuclei

Production and decay of an isotope 271110 of the 110th element were studied. The isotope was produced by 208Pb + 64Ni → 271110 + n reaction. Fourteen α‐decay chains have been assigned to be the decays originating from the isotope 271110. The excitation function of the production cross section was measured. The results have provided a good confirmation of production and decay of the 271110 reported by GSI group. The presence of an isomeric state in 271110 has also been confirmed. Possible isomeric state in 267Hs has also been presented. The production and decay of 272111 has been also investigated in irradiations of 209Bi targets with 64Ni beam. We have observed 14 α‐decay chains in total, that can be assigned, on the basis of their time correlations, to subsequent decays from 272111.

Status of heavy element research using a gas-filled recoil separator at RIKEN

The production and decay of 272 111 has been investigated using a gas-filled recoil ion separator in irradiations of 209 Bi targets with 64 Ni beam at 320, 323 and 326 MeV. We have observed 14 α-decay chains in total, that can be assigned, on the basis of their time correlations, to subsequent decays from 272 111 produced in the 209 Bi( 64 Ni,1n) reaction. The present result is the first clear confirmation for the discovery of 272 111 and its α-decay products, 264 Bh and 268 Mt, reported previously by a GSI group. New information on their half-lives and decay energies as well as the excitation function is presented.

Study of Decays of 271110 and 272111 Produced with 208Pb(64Ni,n) and 209Bi(64Ni,n) Reactions

A gas-filled recoil separator for heavy element research was installed at the experimental hall of RIKEN linear accelerator facility. An acceptance of the separator was measured using a-particles from 241Am source. Measured acceptance was 12.2 msr. Transmissions of the separator were measured with low-energy Pb (0.26 AMeV) and Bi (0.11 AMeV) recoils. It was found that the transmission for Pb (0.26 AMeV) was 0.84, and that for Bi (0.11 AMeV) was 0.33. Equilibrium charge states for Pb and Bi in helium gas were deduced.