The astrophysical implications of low-energy resonances in 22Ne + α

Giesen, U.; Browne, C.P.; Görres, J.; Graff, S.; Iliadis, Christian; Trautvetter, H. P.; Wiescher, M.; Harms, W.; Kratz, K. L.; Pfeiffer, B.; Azuma, R.E.; Buckby, M.; King, J.D.

doi:10.1016/0375-9474(93)90167-v

Cited by 87 publications

(174 citation statements)

References 17 publications

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“…Both of these levels facilitate the triplealpha process leading to the formation of 12 C in stars [38]. Other pronounced α cluster resonance configurations have been found in 16 [42] exhibit resonance features that correspond to α-cluster states. The identification of α-clusters are based on small single particle and large alpha spectroscopic factors.…”

Section: Level Density and Alpha Cluster Structurementioning

confidence: 97%

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Probing astrophysically important states in theMg26nucleus to study neutron sources for thesprocess

et al. 2016

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Section: Level Density and Alpha Cluster Structurementioning

confidence: 97%

“…A number of scattering and transfer measurements ( [50], [51], [52], [42], [53], [54] and [55]) have been performed to investigate the level structure of 26 Mg above the α-threshold. 26 Mg by Longland et al [55] and deBoer et al [58] and 26 Mg(γ, n) 25 Mg measurement by deBoer et al [59].…”

Section: Level Density and Alpha Cluster Structurementioning

confidence: 99%

Probing astrophysically important states in theMg26nucleus to study neutron sources for thesprocess

et al. 2016

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“…Despite several attempts to measure the reaction cross section [52][53][54][55], these experiments failed to reach the low α energies of astrophysical relevance, mostly because cosmic-ray induced background starts to dominate the experimental signatures below E α = 0.5 MeV. A series of indirect measurements via α-particle transfer reactions have been performed to overcome this limitation [56,57]. Alternatively, the 25 Mg(n, γ ) 26 Mg reaction can be used to populate the same excited states as shown in Fig.…”

Section: Mg Reactionmentioning

confidence: 99%

“…In this process most of the neutrons are provided by the 13 C(α, n) 16 O reaction and by the 22 Ne(α, n) 25 Mg reaction. Most of the produced neutrons are captured by light species in competition with 56 Fe, that is the main seed for s-process nucleosynthesis on heavy elements. Among light neutron poisons, 25 Mg and 26 Mg may have a relevant impact on neutron balance, and their neutroncapture cross sections need to be known with high precision, in order to obtain robust s-process calculations.…”

Section: Introductionmentioning

confidence: 99%

Resonance neutron-capture cross sections of stable magnesium isotopes and their astrophysical implications

Massimi¹,

Koehler²,

Bisterzo³

et al. 2012

Phys. Rev. C

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We have measured the neutron capture cross sections of the stable magnesium isotopes 24,25,26 Mg in the energy range of interest to the s process using the neutron time-of-flight facility n_TOF at CERN. Capture events from a natural metal sample and from samples enriched in 25 Mg and 26 Mg were recorded using the total energy method based on C 6 2 H 6 detectors. Neutron resonance parameters were extracted by a simultaneous resonance shape analysis of the present capture data and existing transmission data on a natural isotopic sample. Maxwellian-averaged capture cross sections for the three isotopes were calculated up to thermal energies of 100 keV and their impact on s-process analyses was investigated. At 30 keV the new values of the stellar cross section for 24 Mg, 25 Mg, and 26 Mg are 3.8±0.2 mb, 4.1±0.6 mb, and 0.14±0.01 mb, respectively.

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“…Here, we also include the update input file and additional plots. These rates differ from those presented in Iliadis et al (2010c) in the following ways (see Longland et al 2012 for more details): (1) the inflated weighted average method has been employed to account for the ambiguities in experimental data sets for resonance strengths and energies; (2) normalization of the relative spectroscopic factors reported in Giesen et al (1993) is now performed with respect to the E lab r = 1434 keV resonance rather than the E lab r = 831 keV resonance used in previous work; and (3) a previous ( 6 Li, d) transfer measurement (C. Ugalde 2008, private communication) suggested a spectroscopic factor for the state corresponding to a resonance at E lab r = 588 keV; in Iliadis et al (2010c), this preliminary value is treated as an upper limit; in the new evaluation, this upper limit has been removed and replaced by C 2 S=1. For T > 1.25 GK, rates were extrapolated using Hauser-Feshbach calculations.…”

Section: C2mentioning

confidence: 99%

STARLIB: A next-generation reaction-rate library for nuclear astrophysics

Sallaska¹,

Iliadis²,

Chapmagne³

et al. 2013

Proceedings of XII International Symposium on Nuclei in the Cosmos — PoS(NIC XII)

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STARLIB is a next-generation, all-purpose nuclear reaction-rate library. For the first time, this library provides the rate probability density at all temperature grid points for convenient implementation in models of stellar phenomena. The recommended rate and its associated uncertainties are also included. Currently, uncertainties are absent from all other rate libraries, and, although estimates have been attempted in previous evaluations and compilations, these are generally not based on rigorous statistical definitions. A common standard for deriving uncertainties is clearly warranted. STARLIB represents a first step in addressing this deficiency by providing a tabular, up-to-date database that supplies not only the rate and its uncertainty but also its distribution. Because a majority of rates are lognormally distributed, this allows the construction of rate probability densities from the columns of STARLIB. This structure is based on a recently suggested Monte Carlo method to calculate reaction rates, where uncertainties are rigorously defined. In STARLIB, experimental rates are supplemented with: (1) theoretical TALYS rates for reactions for which no experimental input is available, and (2) laboratory and theoretical weak rates. STARLIB includes all types of reactions of astrophysical interest to Z = 83, such as (p, γ ), (p, α), (α, n), and corresponding reverse rates. Strong rates account for thermal target excitations. Here, we summarize our Monte Carlo formalism, introduce the library, compare methods of correcting rates for stellar environments, and discuss how to implement our library in Monte Carlo nucleosynthesis studies. We also present a method for accessing STARLIB on the Internet and outline updated Monte Carlo-based rates.

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The astrophysical implications of low-energy resonances in 22Ne + α

Cited by 87 publications

References 17 publications

Probing astrophysically important states in theMg26nucleus to study neutron sources for thesprocess

Probing astrophysically important states in theMg26nucleus to study neutron sources for thesprocess

Resonance neutron-capture cross sections of stable magnesium isotopes and their astrophysical implications

STARLIB: A next-generation reaction-rate library for nuclear astrophysics

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