SHE RESEARCH AT RIKEN NISHINA CENTER

To synthesize a new superheavy element, Z = 119, the RIKEN Nishina Center (RNC) has upgraded the existing heavy-ion linac system (called RILAC) to the superconducting linear accelerator system (SRILAC) to enable a hot fusion reaction of51V+248Cm. The upgraded project, called the ‘SHE project’, was completed in 2020. After the commissioning of SRILAC, the first step was to measure the Coulomb barrier distribution for the51V+248Cm system in order to deduce the optimal bombarding energy of the51V beam. The measurement of the synthesis of Z = 119 was then started and is still going. The side-collision effect due to nuclear deformation should play an important role in maximising the synthesis cross section. Since159Tb and248Cm have a similar amount of deformation (β ∼ 0.28), the51V+159Tb reaction was used to study the deformation effect. The51V+159Tb reaction has large fusion reaction cross sections and, therefore, the Coulomb barrier distribution as well as the evaporation residues for the xn, pxn, and αxn exit channels could be measured. The evaporation residue cross sections are compared with those of the simple statistical decay model calculation. © 2024 Jagiellonian University. All rights reserved.