Fission barriers of actinide nuclei with nuclear density functional theory: influence of the triaxial deformation
- PDF / 1,540,231 Bytes
- 10 Pages / 595.276 x 790.866 pts Page_size
- 81 Downloads / 239 Views
Regular Article -Theoretical Physics
Fission barriers of actinide nuclei with nuclear density functional theory: influence of the triaxial deformation Chen Ling, Chao Zhou, Yue Shia Department of Physics, Harbin Institute of Technology, Harbin 150001, People’s Republic of China
Received: 4 January 2020 / Accepted: 16 June 2020 © Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The fission pathway of even–even actinide nuclei have been systematically calculated using the deformationconstrained nuclear density functional theory beyond the second fission barriers within the UNEDF1 energy-density functionals (EDFs). Our calculated results show that, allowing for triaxial deformation, the second fission barriers are lowered by a few hundreds of keV to 2 MeV. For the heaviest actinides, it is found that inclusion of triaxial deformation reduces the outer barrier significantly. Michael Bender
1 Introduction Since the 1950s, spontaneous fission has been understood as a process where heavy compound nuclei undergo a series of deformation changes or elongations, eventually splitting into two or three lighter daughter nuclei. The height (E B ), and in general the shape, of the fission barrier of a nucleus is a fundamental quantity. Indeed, a number of observables related to the fission of a heavy nucleus as well as the fusion of two nuclei depend on E B sensitively [1–6], such as the fission half life, and the fusion cross section. Whether a good description of E B can be achieved in turn provides valuable constraints on the relevant nuclear model used. From a perspective of nuclear mean-field model [7], the total energy (E tot ) of a nucleus is a function of its intrinsic deformations [8,9]. In the fission process, the compound system undergoes a complex shape trajectory towards scission, before splitting up. To determine the optimal/favored trajectory through which a fissioning nucleus most likely undergoes, one needs to perform extensive nuclear calculations as E tot is a function of a large set of shape degrees of freedom. For example, in the recent macroscopic-microscopic calculations [10–16], one typically deals with 5 (or more) a e-mail:
shape degrees of freedom, containing deformation points in the order of a few millions. With the self-consistent mean-field models such as the nuclear density functional theory (DFT) [17–24], the relativistic mean field theory [26,27], or the DFT with the finiterange Gogny force [28–30], performing the above-mentioned amount of separate calculations is nearly impossible. Instead, one picks a few important “active” deformation degrees of freedom to map out E tot , and releases the “background” deformations to be determined self-consistently through the variational process. To balance the needs for a fully minimized fissioning path with respect to the various shape degrees of freedom, and the huge amount of computing time, one frequently chooses the “active” deformations based on the physical insights. Frequently, the calculations enf
Data Loading...
