Speaker
Description
At present, the research into the synthesis of superheavy elements is being pursued under two main goals. One goal is to synthesize elements with larger atomic numbers, and the other is to reach the Island of Stability predicted as the next doubly magic nucleus. The periodic table is currently extended up to element 118, Oganesson (Og) [1], and experiments aimed at the synthesis of element 119 are now in progress. Recently, a successful synthesis experiment $(^{54}$Cr + $^{238}$U $\rightarrow$ $^{292-x}$Lv) has been carried out using a Cr beam [2].
In this work, we investigate the synthesis of superheavy elements using neutron-rich radioactive secondary beams. Since the intensity of secondary beams is significantly lower than that of stable beams, it is often questioned whether measurable evaporation-residue cross sections can be achieved. However, our theoretical analyses indicate that neutron-rich beams offer substantial advantages in both the fusion and decay processes, leading to enhanced evaporation-residue cross sections. The reaction dynamics are analyzed using a multidimensional Langevin approach. The presentation will focus on the following two key mechanisms responsible for the enhancement of the evaporation-residue cross sections:
1. Advantage in the survival probability.
2. Enhancement of the fusion probability through the production of neutron-rich nuclei and dynamic shell evolution
In summary, the production of highly excited compound nuclei on the neutron-rich side of the predicted Island of Stability is important for enhancing both the fusion probability and the survival probability. Although radioactive secondary beams have much lower intensities than stable beams, the unique reaction mechanisms associated with neutron-rich systems are expected to compensate for this disadvantage, resulting in larger evaporation-residue cross sections and improving the prospects for the synthesis of new superheavy elements.
[1] Yu. Ts. Oganessian, et al.,“Results from the first $^{249}$Cf+$^{48}$Ca experiment”. JINR Communication (JINR, Dubna) (2002)
[2] Yu. Ts. Oganessian, et al. Phys. Rev. C 112, 014603 (2025)