Production of unknown neutron-rich transuranium isotopes 245−249Np, 248−251Pu, 248−254Am, and 252−254Cm in multinucleon transfer reactions

The production cross sections of unknown neutron-rich transuranium isotopes of elements Np, Pu, Am and Cm are investigated in multinucleon transfer reactions based on the dinuclear system model with GEMINI code. The influence of the incident energy on the production of neutron-rich transuranium nuclei in actinideactinide collisions is studied. The calculation results show that the final isotopic production cross sections are larger at 1.06-1.10 Vcont than at other energies. Considering the high fissility of transuranium nuclides, 1.06 Vcont is chosen as the optimal incident energy. The N/Z ratio equilibration mechanism in the nucleon transfer process is also studied in this work. The larger difference of N/Z ratio between projectile and target corresponds to larger neutron diffusion during the nucleon exchange process. The 238U beam with high N/Z ratio and neutron-rich actinide targets are good selections to produce neutron-rich transuranium nuclides. The production cross sections of unknown neutron-rich transuranium isotopes 245-249Np, 248-251Pu, 248-254Am, and 252-254Cm are predicted in 238U-induced actinide-based (249Bk, 249Cf, and 252Cf) multinucleon transfer reactions. It is found that a large number of these unknown neutron-rich transuranium nuclei could be generated at the level of nb to µb in the reactions 238U+249Bk and 238U+252Cf. Our research indicates that the reaction 238U+249Bk is a suitable projectile-target combination in the current experimental conditions and the reaction 238U+252Cf could be a promising candidate to produce unknown neutron-rich transuranium nuclides in case that the 252Cf target were to be achieved in the future.

Theoretical progress on production of isotopes in the multinucleon transfer process

As one promising approach for producing nuclei beyond the [Formula: see text]-stability line, the multinucleon transfer (MNT) process has been extensively investigated in past decades. An overview of the theoretical progress on production of isotopes in MNT process is presented. The dinuclear system model, one hybrid approach (GRAZING+DNS model), the improved quantum molecule dynamic model, and the model based on the Langevin equations are summarized. The nucleon transfer mechanisms, such as effects of quasi-elastic and deep inelastic collisions, energy dissipation, [Formula: see text] equilibration, and shell structure in collisions of two complex nuclei are discussed. We present the progress on production of the exotic nuclei near the neutron-drip line, the neutron-rich isotopes near [Formula: see text], and the transuranium nuclei.