Reaction Dynamics of Heavy and Superheavy Element Synthesis – the Physics and the Target Development

Taiki Tanaka (Hubert Curien Pluridisciplinary Institute (IPHC), University of Strasbourg and CNRS, France)

Discovery of new chemical elements has been of fundamental importance in progressing our society – in particular, artificial elements have contributed much to our society in nuclear medicine (atomic number Z = 43; Technetium for computed tomography), nuclear energy (Z = 94 Plutonium), fire alarm detectors (Z = 95 Americium), and neutron sources for non-destructive inspection (Z = 98 Californium). Heavy and superheavy elements have unusual nuclear and chemical properties due to their large number of nucleons and electrons. These may be useful for our future society. Nuclei located around the next doubly magic nuclide beyond 208Pb are expected to have longer half-lives than the known superheavy nuclei, forming “the island of stability”. The long-lived superheavy nuclei would also open new types of chemistry study, which require a longer time to complete chemical procedures. The fist “g-shell” atoms may be appeared at Z = 121 as predicted by Mendeleev’s periodic table.
A few research groups [1-8] have attempted (or will attempt) to synthesize new superheavy isotopes around the island. Understanding the reaction dynamics of heavy and superheavy element synthesis to optimize the reaction is vital for the success of these attempts. In addition, developing innovative materials for extreme beam and rare targets are also vital for the success of these attempts on reaching extreme lower cross-section.
In this talk, I will discuss my contributions towards solving the vital components; (1) study of the capture process [9,10] utilizing quasielastic (QE) barrier distributions [11,12] and evaporation residue nuclei measurement [13] at RIKEN in Japan, (2) study of the quasifission process [14,15] utilizing mass and angle distributions (MADs) [16-18] at the Australian National University in Australia, and (3) the target developments [19] for each study.

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[19] T. Tanaka et al., RIKEN Accel. Prog. Rep. 53, 170 (2020).