Influence of the tensor force on the microscopic heavy-ion interaction potential

Abstract

Background: The tensor interaction is known to play an important role in the nuclear structure studies of exotic nuclei. However, most microscopic studies of low-energy nuclear reactions neglect the tensor force, resulting in a lack of knowledge concerning the effect of the tensor force on heavy-ion collisions. An accurate description of the heavy-ion interaction potential is crucial for understanding the microscopic mechanisms of heavy-ion fusion dynamics. Furthermore, the building blocks of the heavy-ion interaction potential in terms of the ingredients of the effective nucleon-nucleon interaction provides the physical underpinnings for connecting the theoretical results with experiment. The tensor force has never been incorporated for calculating the nucleusnucleus interaction potential. Purpose: The theoretical study of the influence of the tensor force on heavy-ion interaction potentials is required to further our understanding of the microscopic mechanisms entailed in fusion dynamics. Method: The full Skyrme tensor force is implemented into the static Hartree-Fock and dynamic densityconstrained time-dependent Hartree-Fock (DC-TDHF) theory to calculate both static (frozen density) and dynamic microscopic interaction potentials for reactions involving exotic and stable nuclei. Results: The static potentials are found to be systematically higher than the dynamical results, which are attributed to the microscopic dynamical effects included in TDHF. We also show that the dynamical potential barriers vary more significantly by the inclusion of tensor force than the static barriers. The influence of isoscalar and isovector tensor terms is also investigated with the TIJ set of forces. For light systems, the tensor force is found to have an imperceptible effect on the nucleus-nucleus potential. However, for medium and heavy spinunsaturated reactions, the potentials may change from a fraction of an MeV to almost 2 MeV by the inclusion of tensor force, indicating a strong impact of the tensor force on sub-barrier fusion. Conclusions: The tensor force could indeed play a large role in the fusion of nuclei, with spin-unsaturated systems seeing a systematic increase in ion-ion barrier height and width. This fusion hindrance is partly due to static, ground state effects from the inclusion of the tensor force, though additional hindrance appears when studying nuclear dynamics.where H 0 is the simplified functional used in the Sky3D TDHF code [82] and most TDHF calculations. The terms containing the coupling constants A arise from the Skyrme central

Absence of hindrance in a microscopic C12+C12 fusion study

“…The effects of these terms on heavy-ion fusion have been recently studied [64][65][66]. However, a comparison of the nucleus-nucleus potentials calculated with the SLy5 functional (without tensor) [67] and with SLy5t (including tensor) [68] showed that the effect is quite small for 12 C+ 12 C [69].…”

Microscopic studies of production cross sections in multinucleon transfer reaction Ni58+Sn124

“…For details in the energy functional, see Refs. [42,43,51]. This force has been widely used in the fully three-dimensional TDHF calculations in heavy-ion collisions [34][35][36]42,43,[49][50][51]56,57,[59][60][61].…”

“…Quantum effects such as the Pauli principle and antisymmetrization of wave functions are also automatically taken into account in TDHF, which are essential for the manifestation of shell structures during the collision dynamics. TDHF approach has many successful applications in the description of nuclear large amplitude collective motions, as seen in recent applications to fusion [36][37][38][39][40][41][42][43], quasifission [44][45][46][47][48][49][50][51][52], transfer reactions [49,[53][54][55][56][57][58][59][60][61][62][63], fission [64][65][66][67][68], and deep inelastic collisions [69][70][71][72][73][74][75][76][77][78]. However, since the dynamical fluctuation and two-body dissipation are not included in TDHF, the fluctuations of collective variables are found to be considerably underestimated [79,…”

Fusion Dynamics of Low-Energy Heavy-Ion Collisions for Production of Superheavy Nuclei

“…TDHF calculations may be used to compute the ratio of fusion cross sections to capture cross sections. In addition, the TDHF method may be used to explore the effect of the orientation of the projectile and the target at the contact point, and the role of the nuclear shell structure and tensor force [104][105][106][107][108][109][110][111][112][113][114][115].…”