Kyushu University Academic Staff Educational and Research Activities Database
List of Presentations
Kosuke Morita Last modified date:2021.06.15

Professor / Experimental Particle Physics / Department of Physics / Faculty of Sciences

1. 森田浩介, 第113番元素ニホニウムの発見, 国際周期表年 IYPT閉会式, 2019.12.
2. 森田浩介, Present status and perspectives of SHE researches at RIKEN, NN2018, 2018.12.
3. Kosuke Morita, SHE  Research at RIKEN/GARIS, 超重元素国際シンポジウム, 2015.03.
4. 森田 浩介, The discovery of super-heavy element of atomic number Z=113 and beyond
, Nuclei in the Cosmos, 2016.06.
5. 森田 浩介, Nobel Symposium NS160(BacKaskog Castle), Nobel Symposium NS160(BacKaskog Castle), 2016.05.
6. 森田 浩介, Research of Superheavy Element at RIKEN, 第4回核物理部門日米物理学会合同会議, 2014.10.
7. 森田 浩介, Research of Superheavy Element at RIKEN, Zakopane Conference on Nucleart Physics, 2014.08.
8. 森田 浩介, Search for Superheavy Element in Japan, The 3rd International Congress on Natural Sciences with Sisterhood Universities (ICNS2013), 2013.10, 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 three decay-chains which were atributed to the ones originating from the isotope 278113 [1-3]. Two of them [1, 2] consisted of four consecutive a-decays followed by spontaneous fission (SF), following the implantation of a heavy particle in nearly the same position in the semiconductor detector, under an extremely low background condition. The third one [3] consisted of six consecutive a-decays. The fifth and sixth decays are fully consistent with the sequential decays of 262Db and 258Lr in both decay energies and decay times. The isotope 262Db is known to decay by both a-decays (branching ratio ba ̴ 67 %) and SF (bSF ̴ 33 %). These results conclusively lead to the unambiguous production and decay of the isotope 278113 of the 113th element. The observed decay chains are shown in the Figure 1.
The energy of the 70Zn beam at the middle of the target layers was set to 351 MeV. A gas-filled type recoil separator GARIS was used to separate the reaction products from the intense beam and the unwanted charged particles. The reaction products were then implanted into the position sensitive silicon semi-conductor detector followed by a set of timing counters. Net irradiation time was 570 days. A total beam dose was 1.35 × 1020, leading to the production cross section to be 22 +20 –13 fb (fb = 10–39 cm2) with a 1 error.
[1] K. Morita et al., J. Phys. Soc. Jpn. 73 (2004) 2593.
[2] K. Morita et al., J. Phys. Soc. Jpn. 76 (2007) 045001.
[3] K. Morita et al., J. Phys. Soc. Jpn. 81 (2012) 103201.