Speaker
Description
The synthesis of superheavy elements is a major foundational scientific problem of joint interest to both the fields of physics and chemistry. Experimentally, fusion-evaporation reactions are commonly employed for the synthesis of superheavy nuclei, but thus far have only resulted in neutron-deficient superheavy nuclei.
The pursuit of the "island of stability" for superheavy nuclei thus requires novel reaction mechanisms. Multinucleon transfer (MNT) reactions provide a promising pathway for synthesizing neutron-rich heavy and superheavy nuclei, and have attracted extensive attention both experimentally and theoretically, becoming a major topic in nuclear physics. However, due to the complex mass and angle distributions of MNT reaction products, significant challenges exist in their collection and separation [1]. Therefore, the investigation of MNT reactions requires a close integration of experiment and theory.
Covariant density functional theory (CDFT), based on effective field theory and density functional concepts, has achieved great success in the microscopic, self-consistent, and unified description of nuclear structure properties. Its time-dependent extension, known as time-dependent covariant density functional theory (TD-CDFT), is a powerful microscopic tool for the study of nuclear reactions and decays, and has been successfully applied to fusion, fission, and quasifission phenomena. For the study of MNT reactions, since the product wave functions are not eigenstates of the particle number or angular momentum operators, the application of TD-CDFT to MNT requires the combination of particle number projection and angular momentum projection techniques.
In this work, the TD-CDFT approach incorporating particle number and angular momentum projection has been developed to investigate the mass and spin distributions of products in MNT reactions. By calculating the cross-sections for several reaction systems and comparing the results with experimental data, the reliability of the theoretical model in reproducing experimental observations is verified [2]. Furthermore, ternary quasifission in actinide collisions is explored, predicting a possible pathway for the synthesis of neutron-rich heavy nuclei [3]. Finally, the spin distribution and its correlations among the reaction products are analyzed, revealing that, as nucleon transfer increases, the spins of the products become larger and the distributions broader. This effect arises from the conversion of orbital angular momentum into intrinsic spin due to friction between the projectile and target nuclei. Entanglement Shanon entropy analysis of the product spins indicates weak correlations among fragments [4].
[1] Xiaohong Zhou, Zhiyuan Zhang, Zaiguo Gan, et al., Research program of superheavy elements and nuclides based on HIAF (in Chinese). Sci Sin-Phys Mech Astron 50, 112002 (2020).
[2] Dan Dan Zhang, Dario Vretenar, Tamara Nik\v si\' c, Peng Wei Zhao, and Jie Meng, Multinucleon transfer with time-dependent covariant density functional theory, Phys. Rev. C 109, 024614 (2024).
[3] Dan Dan Zhang, Bo Li, Dario Vretenar, Tamara Nik\v si\' c, Zheng Xue Ren, Peng Wei Zhao, and Jie Meng, Ternary quasifission in collisions of actinide nuclei, Phys. Rev. C 109, 024316 (2024).
[4] Dan Dan Zhang, Dario Vretenar, Tamara Nik\v si\' c, Peng Wei Zhao, and Jie Meng, Intrinsic spin distributions in multinucleon transfer reactions, Phys. Lett. B 869, 139828 (2025).