Orateur
Description
Present status and perspectives of the superheavy element (SHE) research at RIKEN are presented. In April 2018, we formed the new SHE Research Group (nSHE RG) and started an experiment to synthesize a new element 119 in the 248Cm(51V,xn)299–x119 reaction using GAs-filled Recoil Ion Separator II (GARIS-II) at RIKEN Ring Cyclotron [1]. The 248Cm target material was supplied from Oak Ridge National Laboratory. In January 2020, RIKEN heavy-ion Linear ACcelerator (RILAC) was upgraded with the 28-GHz superconducting ECR ion source and the superconducting RILAC (SRILAC). We developed the new separator GARIS-III at SRILAC. An optimal reaction energy in the 248Cm + 51V fusion reaction was deduced from the quasielastic barrier distribution extracted by measuring the excitation function of quasielastic backscattering [2–4]. Since October 2020, we have continued the synthesis experiment of element 119 with GARIS-III at SRILAC.
Long-lived isotopes of 261Rf, 262Db, 265Sg, and 266Bh useful for SHE chemistry were synthesized in the 248Cm(18O,5n)261Rf, 248Cm(19F,5n)262Db, 248Cm(22Ne,5n)265Sg, and 248Cm(23Na,5n)266Bh reactions, respectively, and their production and decay properties were investigated using a rotating wheel apparatus for α and SF spectrometry coupled to the GARIS gas-jet system [5,6]. In the conference, the chemistry studies of SHEs such as Rf and Db at the RIKEN AVF cyclotron are also presented.
[1] H. Sakai et al., Eur. Phys. J. A 58, 238 (2022).
[2] T. Tanaka et al., J. Phys. Soc. Jpn. 87, 014201 (2018).
[3] T. Tanaka et al., Phys. Rev. Lett. 124, 052502 (2020).
[4] M. Tanaka et al., J. Phys. Soc. Jpn. 91, 084201 (2022).
[5] H. Haba, EPJ Web Conf. 131, 07006 (2016).
[6] H. Haba et al., Phys. Rev. C 102, 024625 (2020).
