Kosuke Morita

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.

New positive-type photosensitive polyimide having sulfo groups

Abstract A new positive-working photosensitive polyimide (PSPI) has been developed, which is based on polyimide bearing sulfo groups (PIS) and 1-{1,1-bis[4-(2-diazo-1-( 2H )naphthalenone-5-sulfonyloxy)phenyl]ethyl}-4-{1-[4-(2-diazo-1( 2H )naphthalenone-5-sulfonyloxy)phenyl]methylethyl}benzene (S-DNQ) as a photosensitive compound. PIS was prepared by ring-opening polyaddition of 1,3-phenylenediamine-4-sulfonicacid (PDAS), 4,4′-oxydianiline (ODA), and 4,4′-hexafluoropropylidenebis(phthalic anhydride) (6FDA), followed by thermal cyclization in m -cresol. PIS containing 30xa0wt% of S-DNQ showed a sensitivity of 100xa0mJxa0cm −2 and a contrast of 1.7, when it was exposed to 365 nm light followed by developing with 2.38xa0wt% aqueous tetramethylammonium hydroxide (TMAH) solution at room temperature. A fine positive image featuring 10 μm line and space patterns was observed on the film of the photoresist exposed to 200xa0mJxa0cm −2 of UV-light at 365 nm by the contact mode. The positive image was successfully converted to the polyimide pattern by thermal treatment.

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}

We performed two search experiments for a Z=118 Superheavy nucleus in the reactions of 86Kr+208Pb and 84Kr+208Pb. We accumulated a dose of 2.1×1018 ions and 2×1018 ions, respectively. But we did not find any candidate of the evaporation residues with both experiments. A future plan proceeded by RIKEN Superheavy elements experimental group is also described.

111 and its daughter nuclei

RIKEN Nishina Center for Accelerator Based Science, Saitama 350-0198, Japan 1 Faculty of Science, Niigata University, Niigata 950-2181, Japan 2 Graduate School of Science and Technology, Niigata University, Niigata 950-2181, Japan 3 Faculty of Science and Technology, Tokyo University of Science, Chiba 278-8510, Japan 4 Graduate School of Science and Engineering, Yamagata University, Yamagata 990-8560, Japan 5 Department of Physics, Saitama University, Saitama 338-8570, Japan E-mail: daiya@riken.jp

Search for a Z=118 superheavy nucleus in the reaction of Kr beam with Pb target 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.