Neutron star merger ejecta are currently the most viable astrophysical site for -process nucleosynthesis. Fission plays a fundamental role. The manuscript presents an updated scission-point model for fission fragment distributions, which improves agreement with experimental fission yields. Two astrophysical scenarios, based on alternative weak-interaction hypotheses, are employed to reanalyze the role of fission. Regions of the nuclear chart where fission is important are identified, and the impact of fission yields on the final -process abundance distribution is elaborated.
J.-F. Lemaître, S. Goriely, A. Bauswein, and H.-T. Janka
Phys. Rev. C 103, 025806 (2021)
The authors provide a state-of-the-art overview of projection techniques employed in beyond-mean-field many-body methods. They focus on two symmetries that are of critical importance for the description of nuclear spectroscopy, particle number, and angular momentum. The presentation covers formal aspects of symmetry restoration (group theory) and practical aspects related to numerical implementation. A number of illustrative examples are given, including cranked states in odd- nuclei.
Benjamin Bally and Michael Bender
Phys. Rev. C 103, 024315 (2021)
Describing fission as a diffusion process guided by shape-dependent microscopic level densities, the authors address how the available energy at scission is divided into shape distortion and statistical excitation. For the first time, they extract the resulting total fragment kinetic energy for various mass partitions, and study how this observable correlates with the neutron multiplicity. With increasing neutron energy a superlong fission mode appears which drastically changes the observables.
M. Albertsson et al.
Phys. Rev. C 103, 014609 (2021)
The finite-amplitude method is used in solving the local quasiparticle random-phase approximation to calculate the collective inertia along a fission path obtained by the constrained Hartree-Fock-Bogoliubov method with a Skyrme energy-density functional. The collective inertia obtained for the symmetric fission of Pu and Fm is considerably larger than that obtained in the cranking approximation. Including such dynamical residual effects leads to an orders of magnitude difference in the half-lives compared to those calculated using the WKB approximation.
Kouhei Washiyama, Nobuo Hinohara, and Takashi Nakatsukasa
Phys. Rev. C 103, 014306 (2021)