No chance for synthesis of super-heavy nuclei in fusion of symmetric systems

Abstract

Predictions of relatively large cross sections (of about 1 picobarn) for synthesis of super heavy nuclei of Z=122 and Z=124 in cold fusion (1n) reactions of symmetric 154Sm + 150Nd and 154Sm + 154Sm systems by R.K. Choudhury and Y.K. Gupta (2014) [1] are examined. The authors state that this result had been obtained by using the fusion-by-diffusion (FBD) model. As predictions of the original FBD model of Swiatecki, Cap, Siwek-Wilczyńska and Wilczyński had been definitely pessimistic regarding fusion of more symmetric systems (in comparison with equivalent asymmetric systems), we feel compelled to present excitation functions of the 154Sm(150Nd, 1n)303122 and 154Sm(154Sm, 1n)307124 reactions, calculated within the original fusion-by-diffusion model. In accordance with our earlier predictions of a general trend of fusion hindrance for near-symmetric systems, the cross sections for synthesis of 303122 and 307124 nuclides in fusion of these two symmetric systems are found to be extremely small and probably never reachable: about 10−11 pb and 10−13 pb, respectively. It is shown that Choudhury and Gupta obtained their results (overestimating the cross sections by 11 and 13 orders of magnitude) as an effect of an arbitrary and physically unjustified interference in the FBD model.

Keywords

• Fusion-by-diffusion model
• Super-heavy nuclei
• Symmetric systems