Production of unknown neutron-rich transuranium isotopes Np245-249, Pu248-251, Am248-254, and Cm252-254 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 (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 U-238 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 Np245-249, Pu248-251, Am248-254, and Cm252-254 are predicted in U-238-induced actinide-based (Bk-249, Cf-249, and Cf-252) 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 mu b in the reactions U-238 + Bk-249 and U-238 + Cf-252. Our research indicates that the reaction U-238 + Bk-249 is a suitable projectile-target combination in the current experimental conditions and the reaction U-238 + Cf-252 could be a promising candidate to produce unknown neutron-rich transuranium nuclides in case that the Cf-252 target were to be achieved in the future.