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

摘要

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 154 Sm + 150 Nd and 154 Sm + 154 Sm 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 154 Sm( 150 Nd, 1n) 303 122 and 154 Sm( 154 Sm, 1n) 307 124 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 303 122 and 307 124 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.