Neutron capture cross sections of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">Sr</mml:mi></mml:mrow><mml:mprescripts /><mml:mrow /><mml:mrow><mml:mn>86</mml:mn></mml:mrow><mml:mrow /><mml:mrow /></mml:mmultiscripts></mml:mrow></mml:math>and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">Sr</mml:mi></mml:mrow><mml:mpres

Bauer, R.; Bazán, G.; Becker, J. A.; Howe, R.E.; Mathews, Grant J.

doi:10.1103/physrevc.43.2004

“…Hence, the ratio of 87 Sr to 86 Sr should remain close to the inverse of their respective cross-section ratios. Bauer et al [9] reported that cross sections for these two particular reactions have to be known to an accuracy of 5% or better. They measured (n, γ) cross sections on 86 Sr and 87 Sr targets for energies ranging from 100 eV to 1 MeV using TOF facility.…”

Section: B Total Capture Cross Sectionsmentioning

confidence: 99%

“…For example, Bauer et al [9] recommended a set of neutron density, temperature, and mean neutron exposure from the cross section measurements, both for main and weak components. There are a few other works which investigated the same quantities from radiative cross sections [3].…”

Section: Introductionmentioning

confidence: 99%

Neutron capture reactions relevant to thesandpprocesses in the region of theN=50shell closure

Dutta

¹

,

Gangopadhyay

²

,

Bhattacharyya

³

2016

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Radiative thermal neutron capture cross sections for nuclei participating in s-process and pprocess nucleosynthesis in and around N = 50 closed neutron shell have been calculated in statistical semi-microscopic Hauser-Feshbach approach for the energy range of astrophysical interest. A folded optical-model potential is constructed utilizing the standard DDM3Y real nucleon-nucleon interaction. The folding of the interaction with target radial matter densities, obtained from the relativistic-mean-field approach, is done in coordinate space using the spherical approximation. The standard nuclear reaction code TALYS1.8 is used for cross-section calculation. The cross sections are compared with experimental results and reasonable agreements are found for almost all cases. Maxwellian-averaged cross sections (MACS) for the nuclei are presented at a single thermal energy of 30 keV relevant to s-process. We have also presented the MACS values over a range of energy from 5 to 100 keV for neutron magic nuclei with (N = 50).PACS numbers: I. INTRODUCTIONElements heavier than iron are produced via two principle processes, namely, the slow neutron capture process (s-process) and the rapid neutron capture process (r-process), differing in the respective neutron capture timescales with respect to the β-decay half-lives. There is a minor contribution from another process, namely, pprocess, producing a subset of proton-rich isotopes. The detailed study of the heavy element nucleosynthesis was done in the fundamental work of Burbidge et al. [1] and also of Cameron [2]. Recently Käppeler et al. [3] presented a review of progress on the studies of s-process nucleosynthesis with advanced nuclear physics inputs, observational data, and stellar models.While the majority of the theory of the s-process is well-developed, uncertainty still remains in constraining the neutron capture rates of nuclei involved in nucleosynthesis chain. The capture cross sections are highly scattered and uncertain in the energy range appropriate for astrophysical applications. These uncertainties lead to significant errors in determining exact abundances of elements involved in different processes. Many works * Electronic address: saumidutta89@gmail.com † Electronic address: ggphy@caluniv.ac.in ‡ Electronic address: abhattacharyyacu@gmail.com have been devoted to this respect in order to measure the thermal neutron capture cross sections relevant to s-process temperature. However, reactions on some important nuclei are still not available due to their unavailability in the terrestrial laboratory. Käppeler et al. [4] showed the present status of the uncertainty of stellar (n, γ) cross sections and commented that improvements are certainly necessary especially in the mass region below A=120 and above A=180. Some reactions are of significant importance, basically those with closed neutron shells acting as bottlenecks to the s-process reaction flow. They have very low cross-sections and in some scenarios, the s-process reaction flow cannot overcome these bottlen...

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“…For 87 Sr, the recommended value is from experimental measurements (Bauer et al 1991) and the energy dependence is derived from the repositories mentioned above. The choice by K1 (93.8±3.8 mb) is again only slightly smaller than the one of the previous K03 compilation and compatible (somewhat in the higher part of the distribution) with BNL data.…”

Section: Srmentioning

confidence: 99%

Presolar grain isotopic ratios as constraints to nuclear and stellar parameters of AGB nucleosynthesis

Palmerini,

Busso,

Vescovi

et al. 2021

Preprint

0

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Recent models for evolved Low Mass Stars (with M 3 M ), undergoing the AGB phase assume that magnetic flux-tube buoyancy drives the formation of 13 C reservoirs in He-rich layers. We illustrate their crucial properties, showing how the low abundance of 13 C generated below the convective envelope hampers the formation of primary 14 N and the ensuing synthesis of intermediate-mass nuclei, like 19 F and 22 Ne. In the mentioned models, their production is therefore of a purely secondary nature. Shortage of primary 22 Ne has also important effects in reducing the neutron density. Another property concerns AGB winds, which are likely to preserve C-rich subcomponents, isolated by magnetic tension, even when the envelope composition is O-rich. Conditions for the formation of C-rich compounds are therefore found in stages earlier than previously envisaged. These issues, together with the uncertainties related to several nuclear physics quantities, are discussed in the light of the isotopic admixtures of s-process elements in presolar SiC grains of stellar origin, which provide important and precise constraints to the otherwise uncertain parameters. By comparing nucleosynthesis results with measured SiC data, it is argued that such a detailed series of constraints indicates the need for

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“…Hence, the ratio of 87 Sr to 86 Sr should remain close to the inverse of their respective cross-section ratios. Bauer et al [9] reported that cross sections for these two particular reactions have to be known to an accuracy of 5% or better. They measured (n, γ) cross sections on 86 Sr and 87 Sr targets for energies ranging from 100 eV to 1 MeV using TOF facility.…”

Section: B Total Capture Cross Sectionsmentioning

confidence: 99%

“…It is also possible to predict the values of stellar mean neutron exposure relevant to s-process from the measurement of (n, γ) cross sections. For example, Bauer et al [9] recommended a set of neutron density, temperature, and mean neutron exposure from the cross section measurements, both for main and weak components. There are a few other works which investigated the same quantities from radiative cross sections [3].…”

Section: Introductionmentioning

confidence: 99%

Neutron capture reactions relevant to s-process and p-process in the domain of the $N=50$ shell closure

Dutta,

Gangopadhyay,

Bhattacharyya

2016

Preprint

0

View full text Add to dashboard Cite

Radiative thermal neutron capture cross sections for nuclei participating in s-process and pprocess nucleosynthesis in and around N = 50 closed neutron shell have been calculated in statistical semi-microscopic Hauser-Feshbach approach for the energy range of astrophysical interest. A folded optical-model potential is constructed utilizing the standard DDM3Y real nucleon-nucleon interaction. The folding of the interaction with target radial matter densities, obtained from the relativistic-mean-field approach, is done in coordinate space using the spherical approximation. The standard nuclear reaction code TALYS1.8 is used for cross-section calculation. The cross sections are compared with experimental results and reasonable agreements are found for almost all cases. Maxwellian-averaged cross sections (MACS) for the nuclei are presented at a single thermal energy of 30 keV relevant to s-process. We have also presented the MACS values over a range of energy from 5 to 100 keV for neutron magic nuclei with (N = 50).

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Neutron capture cross sections ofSr86andSr

Cited by 5 publications

References 24 publications

Neutron capture reactions relevant to thesandpprocesses in the region of theN=50shell closure

Neutron capture reactions relevant to thesandpprocesses in the region of theN=50shell closure

Presolar grain isotopic ratios as constraints to nuclear and stellar parameters of AGB nucleosynthesis

Neutron capture reactions relevant to s-process and p-process in the domain of the $N=50$ shell closure

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