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

Abstract

The production cross sections of unknown neutron-rich transuranium isotopes of elements Np, Pu, Am and Cm are investigated in multinucleon transfer (MNT) 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 actinide–actinide collisions is studied. The calculation results show that the final isotopic production cross sections are larger at 1.06–1.10 V cont than at other energies. Considering the high fissility of transuranium nuclides, 1.06 V cont 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) MNT 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.