The new KADoNiS v1.0 and its influence on the s-process

Dillmann, I.

doi:10.22323/1.204.0057

Cited by 8 publications

(21 citation statements)

References 21 publications

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“…2 of Liu et al (2018c). We adopted Maxwellian-averaged neutron capture cross section (MACS) values reported in both KADoNiS v0.3 and KADoNiS v1.0 databases 2 (Dillmann et al 2006(Dillmann et al , 2014 for model calculations. Note that MACS is defined as σ i MACS =(<σ i (v)v>/ν T ), where σ i (v) is the (n,γ) cross section of a nuclide i and is a function of the relative neutron velocity v and the mean thermal velocity v T .…”

Section: S-process Nucleosynthesis and Updated Torino Modelsmentioning

confidence: 99%

Presolar Silicon Carbide Grains of Types Y and Z: Their Molybdenum Isotopic Compositions and Stellar Origins

Liu

Stephan

Cristallo

et al. 2019

ApJ

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We report Mo isotopic compositions of 37 presolar SiC grains of types Y (19) and Z (18), rare types commonly argued to have formed in lower-than-solar metallicity asymptotic giant branch (AGB) stars. Direct comparison of the Y and Z grain data with data for mainstream grains from AGB stars of close-to-solar metallicity demonstrates that the three types of grains have indistinguishable Mo isotopic compositions. We show that the Mo isotope data can be used to constrain the maximum stellar temperatures (T MAX ) during thermal pulses in AGB stars. Comparison of FRUITY Torino AGB nucleosynthesis model calculations with the grain data for Mo isotopes points to an origin from low-mass (~1.5-3 M ! ) rather than intermediate-mass (>3-9 M ! ) AGB stars. Because of the low efficiency of 22 Ne(α,n) 25 Mg at the low T MAX values attained in low-mass AGB stars, model calculations cannot explain the large 30 Si excesses of Z grains as arising from neutron capture, so these excesses remain a puzzle at the moment.

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Section: S-process Nucleosynthesis and Updated Torino Modelsmentioning

confidence: 99%

Presolar Silicon Carbide Grains of Types Y and Z: Their Molybdenum Isotopic Compositions and Stellar Origins

Liu

Stephan

Cristallo

et al. 2019

ApJ

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“…The choices for the neutron capture cross sections were taken from the last version of the KADONIS database (see Dillmann et al, 2006;Dillmann, 2014).…”

Section: The Reference Codes For the Stellar Structure And Neutron Camentioning

confidence: 99%

s-Processing from MHD-induced mixing and isotopic abundances in presolar SiC grains

Palmerini

Trippella

Busso

et al. 2018

Geochimica et Cosmochimica Acta

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In the past years the observational evidence that s-process elements from Sr to Pb are produced by stars ascending the socalled Asymptotic Giant Branch (or ''AGB") could not be explained by self-consistent models, forcing researchers to extensive parameterizations. The crucial point is to understand how protons can be injected from the envelope into the He-rich layers, yielding the formation of 13 C and then the activation of the 13 Cða; nÞ 16 O reaction. Only recently, attempts to solve this problem started to consider quantitatively physically-based mixing mechanisms. Among them, MHD processes in the plasma were suggested to yield mass transport through magnetic buoyancy. In this framework, we compare results of nucleosynthesis models for Low Mass AGB Stars (M K 3M ), developed from the MHD scenario, with the record of isotopic abundance ratios of s-elements in presolar SiC grains, which were shown to offer precise constraints on the 13 C reservoir. We find that n-captures driven by magnetically-induced mixing can indeed account for the SiC data quite well and that this is due to the fact that our 13 C distribution fulfils the above constraints rather accurately. We suggest that similar tests should be now performed using different physical models for mixing. Such comparisons would indeed improve decisively our understanding of the formation of the neutron source.

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“…As a matter of fact, the MACS values of a large number of isotopes that were measured relative to the 197 Au(nγ) cross section have been re-evaluated taking these new data into account [41], and these changes are reflected in the new version of the KADoNiS database KADoNiS 1.0. [42]. Other examples are reported in the next sections.…”

Section: The N_tof Facility At Cernmentioning

confidence: 89%

“…Thus far, the TOF method has been utilised for the measurement of another five branching nuclei: 63 Ni [28], 99 Tc [73], 151 Sm [27], 171 Tm [29] and 204 Tl [30], and there are plans to also measure 79 Se in the near future at CERN's n_TOF [78]. At present, in several cases, such as 79 Se, 81,85 Kr, 95 Zr, 185 W and 192 Ir, only theoretical calculations become available (see references cited in [42]), with typical discrepancies of a factor of two or more in the predicted MACS values. The cross section ascribed to these cases in Figure 5 corresponds to the average of the theoretical predictions available for each nucleus [42], while the uncertainty reflects the maximum deviation with respect to the average value.…”

Section: Branching Points Of the S Processmentioning

confidence: 99%

n_TOF: Measurements of Key Reactions of Interest to AGB Stars

et al. 2022

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In the last 20 years, the neutron time-of-flight facility n_TOF at CERN has been providing relevant data for the astrophysical slow neutron capture process (s process). At n_TOF, neutron-induced radiative capture (n,γ) as well as (n,p) and (n,α) reaction cross sections are measured as a function of energy, using the time-of-flight method. Improved detection systems, innovative ideas and collaborations with other neutron facilities have lead to a considerable contribution of the n_TOF collaboration to studying the s process in asymptotic giant branch stars. Results have been reported for stable and radioactive samples, i.e., 24,25,26Mg,26Al, 33S, 54,57Fe, 58,59,62,63Ni, 70,72,73Ge, 90,91,92,93,94,96Zr, 139La, 140Ce, 147Pm, 151Sm, 154,155,157Gd, 171Tm, 186,187,188Os, 197Au, 203,204Tl, 204,206,207Pb and 209Bi isotopes, while others are being studied or planned to be studied in the near future. In this contribution, we present an overview of the most successful achievements, and an outlook of future challenging measurements, including ongoing detection system developments.

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The new KADoNiS v1.0 and its influence on the s-process

Cited by 8 publications

References 21 publications

Presolar Silicon Carbide Grains of Types Y and Z: Their Molybdenum Isotopic Compositions and Stellar Origins

Presolar Silicon Carbide Grains of Types Y and Z: Their Molybdenum Isotopic Compositions and Stellar Origins

s-Processing from MHD-induced mixing and isotopic abundances in presolar SiC grains

n_TOF: Measurements of Key Reactions of Interest to AGB Stars

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