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Confortola, F.; Bemmerer, D.; Costantini, H.; Formicola, A.; Gyürky, Gy.; Bezzon, P.; Bonetti, R.; Broggini, C.; Corvisiero, P.; Elekes, Z.; Fülöp, Zs.; Gervino, G.; Guglielmetti, A.; Gustavino, C.; Imbriani, G.; Junker, M.; Laubenstein, M.; Lemut, A.; Limata, B.; Lozza, V.; Marta, M.; Menegazzo, R.; Prati, P.; Roca, V.; Rolfs, C.; Alvarez, C. Rossi; Somorjai, E.; Straniero, O.; Strieder, F.; Terrasi, F.; Trautvetter, H. P.

doi:10.1103/physrevc.75.065803

Cited by 129 publications

(109 citation statements)

References 34 publications

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“…3. It agrees very well both in absolute normalization and energy dependence with the recent experimental results obtained at the Weizmann Institute [16], the LUNA collaboration [17], at Seattle [18] and by the ERNA collaboration [19].…”

Section: Capture Cross Sectionsupporting

confidence: 87%

Microscopic Nuclear Structure and Reaction Calculations in the FMD Approach

Neff¹,

Feldmeier²,

Langanke³

2011

Proceedings of 11th Symposium on Nuclei in the Cosmos — PoS(NIC XI)

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Fermionic Molecular Dynamics (FMD) is a microscopic many-body approach which has been used successfully to study the structure of light nuclei in the p-and sd-shell. FMD uses a Gaussian wave packet basis which contains the harmonic oscillator shell model and Brink-type cluster model wave functions as limiting cases. A realistic effective interaction that has been derived from the Argonne V18 interaction by treating explicitly short-range central and tensor correlations is employed. We present here a first application of the FMD approach to low-energy nuclear reactions, namely the 3 He(α,γ) 7 Be radiative capture reaction. We divide the Hilbert space into an external region where the system is described as 3 He and 4 He clusters interacting only via the Coulomb interaction and an internal region where the nuclear interaction will polarize the clusters. Polarized configurations are obtained by a variation after parity and angular momentum projection procedure with respect to the parameters of all single particle states. A constraint on the radius of the intrinsic many-body state is employed to obtain polarized clusters at desired distances. The boundary conditions for bound and scattering states are implemented using the Bloch operator. The FMD calculations reproduce the correct energy for the centroid of the 3/2 − and 1/2 − bound states in 7 Be. The charge radius of the ground state is in good agreement with recent experimental results. The FMD calculations also describe well the experimental phase shift data in the 1/2 + , 3/2 + and 5/2 + channels that are important for the capture reaction at low energies. Using the bound and scattering many-body wave functions we calculate the radiative capture cross section. The calculated S factor agrees very well, both in absolute normalization and energy dependence, with the recent experimental data from the Weizmann, LUNA, Seattle and ERNA experiments. 11th Symposium on Nuclei in the Cosmos

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Section: Capture Cross Sectionsupporting

confidence: 87%

Microscopic Nuclear Structure and Reaction Calculations in the FMD Approach

Neff¹,

Feldmeier²,

Langanke³

2011

Proceedings of 11th Symposium on Nuclei in the Cosmos — PoS(NIC XI)

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“…The dominant 7 Be production mechanism is through the capture reaction, 3 He(α, γ) 7 Be; a reaction that has been studied in detail both experimentally [15] and theoretically [16]. The cross section is known to ∼ 3% uncertainty.…”

Section: Thementioning

confidence: 99%

The cosmological⁷Li problem from a nuclear physics perspective

Broggini

Canton

Fiorentini

et al. 2012

J. Cosmol. Astropart. Phys.

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Abstract. The primordial abundance of 7 Li as predicted by Big Bang Nucleosynthesis (BBN) is more than a factor 2 larger than what has been observed in metal-poor halo stars. Herein, we analyze the possibility that this discrepancy originates from incorrect assumptions about the nuclear reaction cross sections relevant for BBN. To do this, we introduce an efficient method to calculate the changes in the 7 Li abundance produced by arbitrary (temperature dependent) modifications of the nuclear reaction rates. Then, considering that 7 Li is mainly produced from 7 Be via the electron capture process 7 Be + e − → 7 Li + ν e , we assess the impact of the various channels of 7 Be destruction. Differently from previous analysis, we consider the role of unknown resonances by using a complete formalism which takes into account the effect of Coulomb and centrifugal barrier penetration and that does not rely on the use of the narrow-resonance approximation. As a result of this, the possibility of a nuclear physics solution to the 7 Li problem is significantly suppressed. Given the present experimental and theoretical constraints, it is unlikely that the 7 Be + n destruction rate is underestimated by the 2.5 factor required to solve the problem. We exclude, moreover, that resonant destruction in the channels 7 Be + t and 7 Be + 3 He can explain the 7 Li puzzle. New unknown resonances in 7 Be + d and 7 Be + α could potentially produce significant effects. Recent experimental results have ruled out such a possibility for 7 Be + d. On the other hand, for the 7 Be + α channel very favorable conditions are required. The possible existence of a partially suitable resonant level in 11 C is studied in the framework of a coupled-channel model and the possibility of a direct measurement is considered.

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“…For this purpose, 3 He( α, γ ) 7 Be reaction rate evaluated by Kontos et al [32] is used, which is within 1.5% of the slightly updated de Boer et al [33] and Takács et al [34] rates. The excitation function adopted in that work closely tracks the LUNA data on 3 He( α, γ ) 7 Be [35,36] , which are the only recent experimental data on this reaction at energies below 300 keV, most relevant for BBN. 6 Li reaction from the present work.…”

Section: Thermonuclear Reaction Rate and Astrophysical Implicationsmentioning

confidence: 99%

“…[ cm 3 Therefore, by using the Kontos et al rate in essence the 6 Li/ 7 Li isotopic ratio is determined by the ratio of two LUNA experimental S-factors in similar setups: The present 2 H( α, γ ) 6 Li data on 6 Li production, and the previous 3 He( α, γ ) 7 Be data [35,36] on 7 Be → 7 Li production. Using the Kontos et al rate [32] , 7 Li/H = (5.2 ± 0.4) ×10 −10 is found, 15% higher than when using CF88.…”

Section: Thermonuclear Reaction Rate and Astrophysical Implicationsmentioning

confidence: 99%

“…This value was adopted as the uncertainty on the beam cur- rent determination. The correction on the gas temperature due to the heating of the beam has been estimated by monitoring the temperature in the reaction chamber and from a previous measurement at LUNA for 3 He gas, in a setup similar to the present one, by double elastic scattering [36] . In our working conditions, the average temperature of the gas impinged by the beam has been estimated to be (318 ± 10) K [6] .…”

Section: Astrophysical S-factor and Nuclear Cross Sectionmentioning

confidence: 99%

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Big Bang 6 Li nucleosynthesis studied deep underground (LUNA collaboration)

Trezzi

Anders

Aliotta

et al. 2017

Astroparticle Physics

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a b s t r a c tThe correct prediction of the abundances of the light nuclides produced during the epoch of Big Bang Nucleosynthesis (BBN) is one of the main topics of modern cosmology. For many of the nuclear reactions that are relevant for this epoch, direct experimental cross section data are available, ushering the so-called "age of precision". The present work addresses an exception to this current status: the 2 H( α, γ ) 6 Li reaction that controls 6 Li production in the Big Bang. Recent controversial observations of 6 Li in metal-poor stars have heightened the interest in understanding primordial 6 Li production. If confirmed, these observations would lead to a second cosmological lithium problem, in addition to the well-known 7 Li problem. In the present work, the direct experimental cross section data on 2 H( α, γ ) 6 Li in the BBN energy range are reported. The measurement has been performed deep underground at the LUNA (Laboratory for Underground Nuclear Astrophysics) 400 kV accelerator in the Laboratori Nazionali del Gran Sasso, Italy. The cross section has been directly measured at the energies of interest for Big Bang Nucleosynthesis for the first time, at E cm = 80, 93, 120, and 133 keV. Based on the new data, the 2 H( α, γ ) 6 Li thermonuclear reaction rate has been derived. Our rate is even lower than previously reported, thus increasing the discrepancy between predicted Big Bang 6 Li abundance and the amount of primordial 6 Li inferred from observations.

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AstrophysicalSfactor of theHe3(α,

Cited by 129 publications

References 34 publications

Microscopic Nuclear Structure and Reaction Calculations in the FMD Approach

Microscopic Nuclear Structure and Reaction Calculations in the FMD Approach

The cosmological⁷Li problem from a nuclear physics perspective

Big Bang 6 Li nucleosynthesis studied deep underground (LUNA collaboration)

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AstrophysicalSfactor of theHe3(α,

Cited by 129 publications

References 34 publications

Microscopic Nuclear Structure and Reaction Calculations in the FMD Approach

Microscopic Nuclear Structure and Reaction Calculations in the FMD Approach

The cosmological7Li problem from a nuclear physics perspective

Big Bang 6 Li nucleosynthesis studied deep underground (LUNA collaboration)

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The cosmological⁷Li problem from a nuclear physics perspective