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Rapagnani, D.; Ananna, Chemseddine; Leva, A. Di; Imbriani, G.; Junker, M.; Pignatari, M.; Best, A.

doi:10.1051/epjconf/202226011031

Cited by 2 publications

(1 citation statement)

References 15 publications

(8 reference statements)

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“…While the 22 Ne(p,γ ) 23 Na is now well measured for the relevant temperatures [43], the impact of the uncertainties in the αcapture channels of 22 Ne affects the calculated production of s-process elements by up to a factor of 10 [44,45], and it is still matter of debate in the literature [46,47]. Future nuclear experiments in underground facilities will drastically improve the present knowledge of such crucial rates [48].…”

Section: Introductionmentioning

confidence: 99%

The s process in massive stars, a benchmark for neutron capture reaction rates

Pignatari,

Gallino,

Reifarth

2023

Eur. Phys. J. A

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A clear definition of the contribution from the slow neutron-capture process (s process) to the solar abundances between Fe and the Sr-Zr region is a crucial challenge for nuclear astrophysics. Robust s-process predictions are necessary to disentangle the contribution from other stellar processes producing elements in the same mass region. Nuclear uncertainties are affecting s-process calculations, but most of the needed nuclear input are accessible to present nuclear experiments or they will be in the near future. Neutron-capture rates have a great impact on the s process in massive stars, which is a fundamental source for the solar abundances of the lighter s-process elements heavier than Fe (weak s-process component). In this work we present a new nuclear sensitivity study to explore the impact on the s process in massive stars of 86 neutron-capture rates, including all the reactions between C and Si and between Fe and Zr. We derive the impact of the rates at the end of the He-burning core and at the end of the C-burning shell, where the $$^{22}$$ 22 Ne($$\alpha $$ α ,n)$$^{25}$$ 25 Mg reaction is is the main neutron source. We confirm the relevance of the light isotopes capturing neutrons in competition with the Fe seeds as a crucial feature of the s process in massive stars. For heavy isotopes we study the propagation of the neutron-capture uncertainties, finding a clear difference of the impact of Fe and Co isotope rates with respect to the rates of heavier stable isotopes. The local uncertainty propagation due to the neutron-capture rates at the s-process branching points is also considered, discussing the example of $$^{85}$$ 85 Kr. The complete results of our study for all the 86 neutron-capture rates are available online. Finally, we present the impact on the weak s process of the neutron-capture rates included in the new ASTRAL library (v0.2).

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Section: Introductionmentioning

confidence: 99%

The s process in massive stars, a benchmark for neutron capture reaction rates

Pignatari,

Gallino,

Reifarth

2023

Eur. Phys. J. A

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Shedding Light on the Origin of Pb204 , the Heaviest s -Process–Only Isotope in the Solar System

Casanovas-Hoste,

Domingo-Pardo,

Lerendegui-Marco

et al. 2024

Phys. Rev. Lett.

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Asymptotic giant branch stars are responsible for the production of most of the heavy isotopes beyond Sr observed in the solar system. Among them, isotopes shielded from the r-process contribution by their stable isobars are defined as s-only nuclei. For a long time the abundance of Pb204, the heaviest s-only isotope, has been a topic of debate because state-of-the-art stellar models appeared to systematically underestimate its solar abundance. Besides the impact of uncertainties from stellar models and galactic chemical evolution simulations, this discrepancy was further obscured by rather divergent theoretical estimates for the neutron capture cross section of its radioactive precursor in the neutron-capture flow, Tl204 (t1/2=3.78 yr), and by the lack of experimental data on this reaction. We present the first ever neutron capture measurement on Tl204, conducted at the CERN neutron time-of-flight facility n_TOF, employing a sample of only 9 mg of Tl204 produced at the Institute Laue Langevin high flux reactor. By complementing our new results with semiempirical calculations we obtained, at the s-process temperatures of kT≈8 keV and kT≈30 keV, Maxwellian-averaged cross sections (MACS) of 580(168) mb and 260(90) mb, respectively. These figures are about 3% lower and 20% higher than the corresponding values widely used in astrophysical calculations, which were based only on theoretical calculations. By using the new Tl204 MACS, the uncertainty arising from the Tl204(n,γ) cross section on the s-process abundance of Pb204 has been reduced from ∼30% down to +8%/−6%, and the s-process calculations are in agreement with the latest solar system abundance of Pb204 reported by K. Lodders in 2021. Published by the American Physical Society 2024

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Cited by 2 publications

References 15 publications

The s process in massive stars, a benchmark for neutron capture reaction rates

The s process in massive stars, a benchmark for neutron capture reaction rates

Shedding Light on the Origin of Pb204 , the Heaviest s -Process–Only Isotope in the Solar System

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