Abstract
The new Atomki-V2 α-nucleus potential is applied to calculate astrophysical reaction rates NA〈σv〉 of intermediate mass and heavy target nuclei from iron (Z=26) up to bismuth (Z=83). Overall, reaction rates of α-induced reactions are provided for 4359 target nuclei, covering as well neutron-deficient as extremely neutron-rich target nuclei from the proton to the neutron dripline. Contrary to previous rate compilations, these new calculations include all relevant exit channels with the dominating (α, xn) reactions for neutron-rich target nuclei.
Highlights
Calculation of (α, γ ) cross sections for heavy target nuclei is mainly sensitive to the α-nucleus optical model potential (AOMP)
As Tα,0 depends only on the chosen AOMP, experimental data for (α, γ ) cross sections below the neutron threshold and for (α,n) cross sections above the sensitivity study has identified some key reactions for a variety neutron threshold are appropriate to constrain the AOMP without of relevant astrophysical conditions [15]; a few of these reactions were measured almost simultaneously [16,17]
Later it was pointed out that the tail of the imaginary potential at radii much larger than the colliding nuclei affects the calculated reaction cross sections at very low energies [18] which is the astrophysically relevant energy region. This tail of the imaginary potential is not well constrained, e.g. by experimental elastic scattering data. This holds for all global AOMPs which are used for the calculation of astrophysical reaction rates
Summary
The Atomki-V2 potential is based on the double-folding approach [22,23,24]. As a consequence, the number of adjustable. This holds for all global AOMPs which are used for the calculation of astrophysical reaction rates To avoid such complications with the tail of the imaginary potential, total reaction cross sections of α-induced reactions were calculated using a simple barrier transmission approach in combination with the real part of the Atomki-V1 potential which is well-constrained by experimental scattering data. The Atomki-V2 potential in the present study combines the parameter-free real part of the Atomki-V1 potential with a narrow, deep, and sharp-edged imaginary part of Woods–Saxon type with a depth W0 = 50 MeV, radius R = R0 × A1T/3 with R0 = 1.0 fm, and diffuseness a = 0.1 fm This combination ensures that the total reaction cross section remains very close to the simple barrier transmission approach; typical deviations are of the order of 10% [18]. The necessary modifications to the TALYS code are listed in Appendix A
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