Actinide materials for the synthesis of heaviest nuclei*

The use of heavy actinides as targets in “hot fusion” reactions with intense ⁴⁸Ca ion beams has enabled a significant expansion of the nuclear chart, adding five new elements and more than 50 new heaviest isotopes since 2000, and providing evidence for the existence of the predicted “island of stability” for super-heavy nuclei.  These discoveries, made using the Dubna Gas-Filled Recoil Separator at the Joint Institute for Nuclear Research (JINR) in Russia [1], have utilized actinide targets from specialized facilities at Oak Ridge National Laboratory (ORNL) and the Research Institute of Advanced Reactors at Dmitrovgrad.  These facilities, including the High Flux Isotope Reactor and Radiochemical Engineering Development Center at ORNL [2], provide unique capabilities to produce, separate, and purify rare actinide materials, and fabricate actinide targets.  New, more powerful accelerator facilities have been developed at JINR and at RIKEN in Japan to expand research on super-heavy nuclei, including the search for new elements 119 and 120.  These facilities will require increased quantities of actinide target materials, including ²⁴⁸Cm, ²⁴⁹Bk, and mixed Cf.  This paper will review the role of actinide materials in advancing super-heavy element research, as well as opportunities to enhance the production of actinide target materials for the synthesis of super-heavy nuclei.

[1] Yu. Ts. Oganessian and V. K. Utyonkov, Nucl. Phys. A 944, 62 (2015).

[2] J. B. Roberto, et al., Nucl. Phys. A 944, 99 (2015).