Large collection of astrophysicalSfactors and their compact representation

Abstract

Numerous nuclear reactions in the crust of accreting neutron stars are strongly affected by dense plasma environment. Simulations of superbursts, deep crustal heating and other nuclear burning phenomena in neutron stars require astrophysical S-factors for these reactions (as a function of center-of-mass energy E of colliding nuclei). A large database of S-factors is created for about 5,000 non-resonant fusion reactions involving stable and unstable isotopes of Be, B, C, N, O, F, Ne, Na, Mg, and Si. It extends the previous database of about 1,000 reactions involving isotopes of C, O, Ne, and Mg. The calculations are performed using the São Paulo potential and the barrier penetration formalism. All calculated S-data are parameterized by an analytic model for S(E) proposed before [Phys. Rev. C 82, 044609 (2010)] and further elaborated here. For a given reaction, the present S(E)-model contains three parameters. These parameters are easily interpolated along reactions involving isotopes of the same elements with only seven input parameters, giving an ultracompact, accurate, simple, and uniform database. The S(E) approximation can also be used to estimate theoretical uncertainties of S(E) and nuclear reaction rates in dense matter, as illustrated for the case of the 34 Ne+ 34 Ne reaction in the inner crust of an accreting neutron star.

Reliability of the double-folding potential for fusion cross sections of light systems

“…(16) where σ(E) is the calculated cross section using DFM and DFC potentials in comparison with the analytical S-factor of Afanasjev et. al [34] and Gasques et. al [35].…”

“…al. [34]. Another analytical expression of S(E) for the fusion [35] whereas the dashed-dotted line is the results of Afanasjev et.…”

“…All the extrapolations give a good description of the average of the data in the energy range of E = 2.5 MeV to 7 MeV with very small order of magnitude differences between A-W and the double folding potentials calculations. Only the analytical prediction from Afanasjev [34] gives very low extrapolation of the data at very low energy. The predictions of S * (E) by different potential models are presented in Figures 5 One of the important basic quantity needed for understanding the nature of stellar evolution and nucleosynthesis is the reaction rate.…”

“…Another analytical expression of S(E) for the fusion [35] whereas the dashed-dotted line is the results of Afanasjev et. al [34]. The experimental data are taken from Ref.…”

Nucleus-nucleus potential with shell-correction contribution

“…Heavy-ion fusion at low energies is very important in the physics of stars [8,11,12]. As a result, the nucleus-nucleus interaction potential is a key ingredient for the description of various nuclear reactions in the nature.…”