Constraining the 12C+12C astrophysical S-factors with the 12C+13C measurements at very low energies

Zhang, N.T.; Wang, X.Y.; Tudor, D.; Bucher, B.; Burducea, I.; Chen, H.; Chen, Z.J.; Chesneanu, D.; Chilug, A. I.; Gasques, L. R.; Ghiţă, D.; Gomoiu, Claudia; Hagino, K.; Kubono, S.; Li, Y. J.; Lin, C. J.; Lin, Weiping; Margineanu, R.M.; Pantelica, A.; Stefanescu, I.; Straticiuc, M.; Tang, Xiaodong; Trache, L.; Umar, A. S.; Xin, Wenyu; Xu, Shaohang; Xu, Y.

doi:10.1016/j.physletb.2019.135170

Cited by 24 publications

(56 citation statements)

References 30 publications

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“…As a result, with current experimental uncertainties, the bounds of the C-burning reaction rate curves result in a wide range of s-process and p-process abundances [10]. New measurements on nearby systems like 13 C+ 12 C [11] have also been performed to establish bounds for the low-energy behavior of 12 C+ 12 C, as the large resonances and oscillations in the sub-barrier region are absent from the asymmetric systems.…”

Section: Introductionmentioning

confidence: 99%

Absence of hindrance in a microscopic C12+C12 fusion study

2019

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Background: Studies of low-energy fusion of light nuclei are important in astrophysical modeling, with small variations in reaction rates having a large impact on nucleosynthesis yields. Due to the lack of experimental data at astrophysical energies, extrapolation and microscopic methods are needed to model fusion probabilities. Purpose: To investigate deep sub-barrier 12 C+ 12 C fusion cross sections and establish trends for the S factor. Method: Microscopic methods based on static Hartree-Fock and time-dependent Hartree-Fock (TDHF) meanfield theory are used to obtain 12 C+ 12 C ion-ion fusion potentials. Fusion cross sections and astrophysical S factors are then calculated using the incoming wave boundary condition method. Results: Both density-constrained frozen Hartree-Fock (DCFHF) and density-constrained TDHF (DC-TDHF) predict a rising S factor at low energies, with DC-TDHF predicting a slight damping in the deep sub-barrier region (≈1 MeV). Comparison between DC-TDHF calculations and maximum experimental cross sections in the resonance peaks are good. However, the discrepancy in experimental low-energy results inhibits interpretation of the trend. Conclusions: Using the fully microscopic DCFHF and DC-TDHF methods, no S factor maximum is observed in the 12 C+ 12 C fusion reaction. In addition, no extreme sub-barrier hindrance is predicted at low energies. The development of a microscopic theory of fusion including resonance effects, as well as further experiments at lower energies must be done before the deep sub-barrier behavior of the reaction can be established.

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Section: Introductionmentioning

confidence: 99%

Absence of hindrance in a microscopic C12+C12 fusion study

2019

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“…A further reduction of a factor of 2.5 was obtained, enclosing the scattering chamber in dry nitrogen to minimize leaks into the rest gas within the chamber. The bulk contamination finally achieved by the Zhang et al (2020); in fact, it has been observed that the 12 C+ 13 C and 13 C+ 13 C cross-sections at energies below and above the Coulomb barrier are upper bounds of the nonresonant contribution of the 12 C+ 12 C cross-section. The measurement of the 13 C+ 13 C reaction was performed by studying the 12 C( 13 C, p) 24 Na channel; 24 Na has a halflife of 15.0 h, allowing an activation measurement.…”

Section: State-of-the-artmentioning

confidence: 99%

The Study of Key Reactions Shaping the Post-Main Sequence Evolution of Massive Stars in Underground Facilities

Ferraro

Ciani

Boeltzig

et al. 2021

Front. Astron. Space Sci.

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The chemical evolution of the Universe and several phases of stellar life are regulated by minute nuclear reactions. The key point for each of these reactions is the value of cross-sections at the energies at which they take place in stellar environments. Direct cross-section measurements are mainly hampered by the very low counting rate and by cosmic background; nevertheless, they have become possible by combining the best experimental techniques with the cosmic silence of an underground laboratory. In the nineties, the LUNA (Laboratory for Underground Nuclear Astrophysics) collaboration opened the era of underground nuclear astrophysics, installing first a homemade 50 kV and, later on, a second 400 kV accelerator under the Gran Sasso mountain in Italy: in 25 years of experimental activity, important reactions responsible for hydrogen burning could have been studied down to the relevant energies thanks to the high current proton and helium beams provided by the machines. The interest in the next and warmer stages of star evolution (i.e., post-main sequence and helium and carbon burning) drove a new project based on an ion accelerator in the MV range called LUNA-MV, able to deliver proton, helium, and carbon beams. The present contribution is aimed to discuss the state of the art for some selected key processes of post-main sequence stellar phases: 12C(α,γ)16O and 12C+12C are fundamental for helium and carbon burning phases, and 13C(α,n)16O and 22Ne(α,n)25Mg are relevant to the synthesis of heavy elements in AGB stars. The perspectives opened by an underground MV facility will be highlighted.

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“…= 2.1 MeV with large uncertainties. Three different kinds of extrapolations have been used to estimate the reaction cross section at lower energies [192][193][194][195][196][197][198]. A recent 24 Mg(α, α ) 24 Mg experiment at RCNP provides important information for the resonances at stellar energies [199].…”

Section: Helium and Carbon Burningsmentioning

confidence: 99%

Progress in nuclear astrophysics of east and southeast Asia

Aziz

Ahmad²,

Ahn³

et al. 2021

AAPPS Bull.

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Nuclear astrophysics is an interdisciplinary research field of nuclear physics and astrophysics, seeking for the answer to a question, how to understand the evolution of the universe with the nuclear processes which we learn. We review the research activities of nuclear astrophysics in east and southeast Asia which includes astronomy, experimental and theoretical nuclear physics, and astrophysics. Several hot topics such as the Li problems, critical nuclear reactions and properties in stars, properties of dense matter, r-process nucleosynthesis, and ν-process nucleosynthesis are chosen and discussed in further details. Some future Asian facilities, together with physics perspectives, are introduced.

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Constraining the 12C+12C astrophysical S-factors with the 12C+13C measurements at very low energies

Cited by 24 publications

References 30 publications

Absence of hindrance in a microscopic C12+C12 fusion study

Absence of hindrance in a microscopic C12+C12 fusion study

The Study of Key Reactions Shaping the Post-Main Sequence Evolution of Massive Stars in Underground Facilities

Progress in nuclear astrophysics of east and southeast Asia

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