Nuclear and astrophysical aspects of 18O(p, γ)19F

Wiescher, M.; Becker, H.W.; Görres, J.; Kettner, K. U.; Trautvetter, H. P.; Kieser, W.E.; Rolfs, C.; Azuma, R.E.; Jackson, K. P.; Hammer, J. W.

doi:10.1016/0375-9474(80)90451-0

Cited by 93 publications

(128 citation statements)

References 57 publications

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“…In particular, the E cm = 150 keV broad resonance and the direct capture dominate the reaction rate at the astrophysically relevant temperature for AGB nucleosynthesis. Wiescher et al (1980) and Vogelaar et al (1990) have directly determined the magnitude of all the relevant states, down to E cm = 89 keV. For the present work, we adopt the reaction rate given in the recent compilation by Iliadis et al (2010).…”

Section: Reaction Rate Uncertaintiesmentioning

confidence: 99%

Effects of nuclear cross sections on¹⁹F nucleosynthesis at low metallicities

Cristallo

Leva

Imbriani

et al. 2014

A&A

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Context. The origin of fluorine is a longstanding problem in nuclear astrophysics. It is widely recognized that asymptotic giant branch (AGB) stars are among the most important contributors to the Galactic fluorine production. Aims. In general, extant nucleosynthesis models overestimate the fluorine production by AGB stars with respect to observations. Although those differences are rather small at solar metallicity, low metallicity AGB stellar models predict fluorine surface abundances up to one order of magnitude larger than the observed ones. Methods. As part of a project devoted to reducing the uncertainties in the nuclear physics that affect the nucleosynthesis in AGB stellar models, we review the relevant nuclear reaction rates involved in the fluorine production or destruction. We perform this analysis on a model with initial mass M = 2 M and Z = 0.001. Results. We found that the major uncertainties are due to the 13 C(α,n) 16 O, the 19 F(α,p) 22 Ne, and the 14 N(p,γ) 15 O reactions. A change in the corresponding reaction rates within the present experimental uncertainties implies surface 19 F variations at the AGB tip lower than 10%, thus much smaller than observational uncertainties. For some α capture reactions, however, cross sections at astrophysically relevant energies are determined on the basis of nuclear models, in which some low-energy resonance parameters are very poorly known. Thus, larger variations in the rates of those processes cannot be excluded. That being so, we explore the effects of the variation in some α capture rates well beyond the current published uncertainties. The largest 19 F variations are obtained by varying the 15 N(α,γ) 19 F and the 19 F(α,p) 22 Ne reactions. Conclusions. The currently estimated uncertainties of the nuclear reaction rates involved in the production and destruction of fluorine produce minor 19 F variations in the ejecta of AGB stars. Analysis of some α capture processes that assume a wider uncertainty range determines 19 F abundances in better agreement with recent spectroscopic fluorine measurements at low metallicity. In the framework of this scenario, the 15 N(α,γ) 19 F and the 19 F(α,p) 22 Ne reactions show the strongest effects on fluorine nucleosynthesis. The presence of poorly known low-energy resonances make such a scenario possible, even if it is unlikely. We plan to measure these resonances directly.

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Section: Reaction Rate Uncertaintiesmentioning

confidence: 99%

Effects of nuclear cross sections on¹⁹F nucleosynthesis at low metallicities

Cristallo

Leva

Imbriani

et al. 2014

A&A

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“…In the past, several researchers have employed bound-state square-well potentials instead of Woods-Saxon potentials (see, for example, Rolfs 1973 ;Trautvetter & Rolfs 1975). However, it was shown recently (Wiescher et al 1980 ;Powell et al 1999) that the use of square-well potentials sometimes overpredicts calculated single-particle direct capture cross sections by a factor of 3.…”

Section: Broad-resonance Ratesmentioning

confidence: 99%

Proton‐induced Thermonuclear Reaction Rates for A = 20–40 Nuclei

Iliadis

D’Auria

Starrfield

et al. 2001

ASTROPHYS J SUPPL S

284

419

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Proton-induced reaction rates on 26 stable and 29 unstable target nuclei in the mass A \ 20È40 region have been evaluated and compiled. Recommended reaction rates, assuming that all interacting nuclei are in the ground state, are presented in tabular form on a temperature grid in the range T \ 0.01È10.0 GK. Most reaction rates involving stable targets were normalized to a set of measured standard resonance strengths in the sd shell. For the majority of reaction rates, experimental information from transfer reaction studies has been used consistently. Our results are compared with recent statistical model (HauserFeshbach) calculations. Reaction rate uncertainties are presented and amount to several orders of magnitude for many of the reactions. Several of these reaction rates and/or their corresponding uncertainties deviate from results of previous compilations. In most cases, the deviations are explained by the fact that new experimental information became available recently. Examples are given for calculating reaction rates and reverse reaction rates for thermally excited nuclei from the present results. The survey of literature for this review was concluded in 2000 August.

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“…By FRESCO we calculated the bound state wave function of the given level of the target nucleus on which a proton is captured and the wave function of the incoming proton in the field of the target nucleus. We calculated the bound state wave functions using the Woods-Saxon potential [2]. The scattered wave function of the proton can be also calculated by the Woods-Saxon potential or for instance by the optical model potential.…”

Section: Analysis and Resultsmentioning

confidence: 99%

“…A very thorough measurement of the 18 O(p, γ) 19 F in the energy range E p = 0.08-2.2 MeV was performed by Wiescher et al [2] where the direct part of the (p, γ) capture was determined experimentally and also calculated theoretically. Later, Buckner et al [3], when investigating reaction rates of 18 O(p, γ) 19 F, measured the cross section and determined the direct part of this capture using different capture models.…”

Section: Introductionmentioning

confidence: 99%

The astrophysical S-factor of the direct ¹⁸O(p, γ)¹⁹F capture by the ANC method

et al. 2017

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Abstract. We attempted to determine the astrophysical S-factor of the direct part of the 18 O(p, γ) 19 F capture by the indirect method of asymptotic normalization coefficients (ANC). We measured the differential cross section of the transfer reaction 18 O( 3 He, d) 19 F at a 3 He energy of 24.6 MeV. The measurement was realized on the cyclotron of the NPI inŘež, Czech Republic, with the gas target consisting of the high purity 18 O (99.9 %). The reaction products were measured by eight ∆E-E telescopes composed from thin and thick silicon surface-barrier detectors. The parameters of the optical model for the input channel were deduced by means of the code ECIS and the analysis of transfer reactions to 12 levels of the 19 F nucleus up to 8.014 MeV was made by the code FRESCO. The deduced ANCs were then used to specify the direct contribution to the 18 O(p, γ) 19 F capture process and were compared with the mutually different results of two works.

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Nuclear and astrophysical aspects of 18O(p, γ)19F

Cited by 93 publications

References 57 publications

Effects of nuclear cross sections on¹⁹F nucleosynthesis at low metallicities

Effects of nuclear cross sections on¹⁹F nucleosynthesis at low metallicities

Proton‐induced Thermonuclear Reaction Rates for A = 20–40 Nuclei

The astrophysical S-factor of the direct ¹⁸O(p, γ)¹⁹F capture by the ANC method

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Nuclear and astrophysical aspects of 18O(p, γ)19F

Cited by 93 publications

References 57 publications

Effects of nuclear cross sections on19F nucleosynthesis at low metallicities

Effects of nuclear cross sections on19F nucleosynthesis at low metallicities

Proton‐induced Thermonuclear Reaction Rates for A = 20–40 Nuclei

The astrophysical S-factor of the direct 18O(p, γ)19F capture by the ANC method

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Product

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Effects of nuclear cross sections on¹⁹F nucleosynthesis at low metallicities

Effects of nuclear cross sections on¹⁹F nucleosynthesis at low metallicities

The astrophysical S-factor of the direct ¹⁸O(p, γ)¹⁹F capture by the ANC method