Measurement of the branching ratio for β -delayed α decay of 16 N

Refsgaard, J.; Kirsebom, O. S.; Dijck, Elwin; Fynbo, H. O. U.; Lund, M. V.; Portela, Mayerlin Nunez; Raabe, R.; Randisi, G.; Renzi, Francesca; Sambi, S.; Sytema, A.; Willmann, Lorenz; Wilschut, H. W.

doi:10.1016/j.physletb.2015.11.047

Cited by 12 publications

(7 citation statements)

References 46 publications

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“…Our value for b βα is significantly larger than the literature value of (1.20 ± 0.05) × 10 −5 [19,28], but consistent with the less precise values of (1.3 ± 0.3) × 10 −5 obtained by Ref. [29] and (1.49 ± 0.05(stat) +0.0 −0.10 (sys)) × 10 −5 obtained by us in a previous study using a different experimental technique [30].…”

supporting

confidence: 92%

First Accurate Normalization of the β -delayed α Decay of N16
Kirsebom¹,
Münch²,
Törnqvist³
et al. 2018
Phys. Rev. Lett.
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The 12 C(α, γ) 16 O reaction plays a central role in astrophysics, but its cross section at energies relevant for astrophysical applications is only poorly constrained by laboratory data. The reduced α width, γ11, of the bound 1 − level in 16 O is particularly important to determine the cross section. The magnitude of γ11 is determined via sub-Coulomb α-transfer reactions or the β-delayed α decay of 16 N, but the latter approach is presently hampered by the lack of sufficiently precise data on the β-decay branching ratios. Here we report improved branching ratios for the bound 1 − level [b β,11 = (5.02 ± 0.10) × 10 −2 ] and for β-delayed α emission [b βα = (1.59 ± 0.06) × 10 −5 ]. Our value for b βα is 33% larger than previously held, leading to a substantial increase in γ11. Our revised value for γ11 is in good agreement with the value obtained in α-transfer studies and the weighted average of the two gives a robust and precise determination of γ11, which provides significantly improved constraints on the 12 C(α, γ) cross section in the energy range relevant to hydrostatic He burning.

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confidence: 92%

First Accurate Normalization of the β -delayed α Decay of N16
Kirsebom¹,
Münch²,
Törnqvist³
et al. 2018
Phys. Rev. Lett.
7
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25
0
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“…The experimental technique involves implanting 11 Be ions in a finely segmented Si-detector and counting the implantations and decays. This method has successfully been used in several other cases to measure β-delayed particles, even very weak branches, from 6 He [14,15], 11 Li [16], 12 B and 12 N [17], 8 B [18] and 16 N [19]. The β transition and the populated daughter states in 11 B are characterised by fitting an R-matrix expression to the observed spectrum and deriving values for the reduced Gamow-Teller (GT) matrix elements, as well as level energies and partial widths.…”

Section: Introductionmentioning

confidence: 99%

Clarification of large-strength transitions in the β decay of Be11

et al. 2019

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The shape and normalisation of the β-delayed α spectrum from 11 Be was measured by implanting 11 Be ions in a segmented Si detector. The spectrum is found to be dominated by a well-known transition to the 3/2 + state at Ex = 9.87 MeV in 11 B. A significant increase in the observed decay strength towards the higher end of the Q β window means, however, that the 9.87 MeV state cannot alone be responsible for the transition. Using the R-matrix framework we find that the inclusion of an extra 3/2 + state at Ex = 11.49(10) MeV is required in order to obtain a satisfactory description of the spectrum. Both states show large widths towards α decay, exhausting significant fractions of the Wigner limit, a typical signature of α clusterisation. The observed Gamow-Teller strength indicate large overlaps between the two states and the ground state of 11 Be.

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“…Another study has been recently performed at KVI where the goal was to determine the total βα branching ratio (Refsgaard et al, 2016) . A review of each of these analyses has been reserved for later in this work, Sec.…”

Section: Return To Indirect Techniques ('93-present)mentioning

confidence: 99%

The C12(α,γ)O16
deBoer
¹
,
Görres
²
,
Wiescher
³

et al. 2017
Rev. Mod. Phys.
190
8
143
1
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The creation of carbon and oxygen in our universe is one of the forefront questions in nuclear astrophysics. The determination of the abundance of these elements is key to both our understanding of the formation of life on earth and to the life cycles of stars. While nearly all models of different nucleosynthesis environments are affected by the production of carbon and oxygen, a key ingredient, the precise determination of the reaction rate of 12 C(α, γ) 16 O, has long remained elusive. This is owed to the reaction's inaccessibility, both experimentally and theoretically. Nuclear theory has struggled to calculate this reaction rate because the cross section is produced through different underlying nuclear mechanisms. Isospin selection rules suppress the E1 component of the ground state cross section, creating a unique situation where the E1 and E2 contributions are of nearly equal amplitudes. Experimentally there have also been great challenges. Measurements have been pushed to the limits of state of the art techniques, often developed for just these measurements. The data have been plagued by uncharacterized uncertainties, often the result of the novel measurement techniques, that have made the different results challenging to reconcile. However, the situation has markedly improved in recent years, and the desired level of uncertainty, ≈10%, may be in sight. In this review the current understanding of this critical reaction is summarized. The emphasis is placed primarily on the experimental work and interpretation of the reaction data, but discussions of the theory and astrophysics are also pursued. The main goal is to summarize and clarify the current understanding of the reaction and then point the way forward to an improved determination of the reaction rate.

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Measurement of the branching ratio for β -delayed α decay of 16 N

Cited by 12 publications

References 46 publications

First Accurate Normalization of the β -delayed α Decay of N16
Kirsebom¹,
Münch²,
Törnqvist³
et al. 2018
Phys. Rev. Lett.
7
0
25
0
View full text Add to dashboard Cite

First Accurate Normalization of the β -delayed α Decay of N16
Kirsebom¹,
Münch²,
Törnqvist³
et al. 2018
Phys. Rev. Lett.
7
0
25
0
View full text Add to dashboard Cite

Clarification of large-strength transitions in the β decay of Be11

The C12(α,γ)O16
deBoer
¹
,
Görres
²
,
Wiescher
³

et al. 2017
Rev. Mod. Phys.
190
8
143
1
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Measurement of the branching ratio for β -delayed α decay of 16 N

Cited by 12 publications

References 46 publications

First Accurate Normalization of the β -delayed α Decay of N16Kirsebom1, Münch2, Törnqvist3 et al. 2018Phys. Rev. Lett.70250View full textAdd to dashboardCite

First Accurate Normalization of the β -delayed α Decay of N16Kirsebom1, Münch2, Törnqvist3 et al. 2018Phys. Rev. Lett.70250View full textAdd to dashboardCite

Clarification of large-strength transitions in the β decay of Be11

The C12(α,γ)O16deBoer1, Görres2, Wiescher3 et al. 2017Rev. Mod. Phys.19081431View full textAdd to dashboardCite

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First Accurate Normalization of the β -delayed α Decay of N16
Kirsebom¹,
Münch²,
Törnqvist³
et al. 2018
Phys. Rev. Lett.
7
0
25
0
View full text Add to dashboard Cite

First Accurate Normalization of the β -delayed α Decay of N16
Kirsebom¹,
Münch²,
Törnqvist³
et al. 2018
Phys. Rev. Lett.
7
0
25
0
View full text Add to dashboard Cite

The C12(α,γ)O16
deBoer
¹
,
Görres
²
,
Wiescher
³

et al. 2017
Rev. Mod. Phys.
190
8
143
1
View full text Add to dashboard Cite