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Mohr, P.

doi:10.1103/physrevc.79.065804

Cited by 32 publications

(43 citation statements)

References 62 publications

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“…This reaction has been studied using potential models [5,6] and microscopic cluster models [7] assuming 3 He+ 4 He cluster wave functions. Polarization effects were considered by including the 6 Li+p channel in [8,9]. Consistent ab initio calculations starting from realistic interactions have not been possible up to now.…”

Section: Introductionmentioning

confidence: 99%

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: Introductionmentioning

confidence: 99%

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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“…In addition, recent work of the ERNA (European recoil mass separator for nuclear astrophysics) Collaboration [15] is in conflict with the data from Ref. [8] and highlights the importance of precise measurements at medium energies, without which the theoretical extrapolations would be less constrained (see below).Around the time when the ERNA data were published, none of the available theoretical calculations could fit the available data over a large energy range between 100 keV and 2.5 MeV [16]. This situation has changed after the recent theoretical work based on a fully microscopic calculation using a realistic effective interaction [17].…”

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confidence: 99%

“…Around the time when the ERNA data were published, none of the available theoretical calculations could fit the available data over a large energy range between 100 keV and 2.5 MeV [16]. This situation has changed after the recent theoretical work based on a fully microscopic calculation using a realistic effective interaction [17].…”

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confidence: 99%

New measurement of the3He(α,γ)7Be cro

et al. 2012

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We report on a new cross-section measurement for the 3 He(α, γ ) 7 Be reaction at three medium energies of E c.m. between 1 and 3 MeV. The interest stems from the significant role played by the reaction in calculating an accurate solar neutrino flux and the primordial 7 Li abundance. The energy dependence of the astrophysical S 34 factor observed in the present work, especially above 1 MeV, highlights the need to constrain theories in order to obtain a precise extrapolated value for S 34 (0). In this context, a comparison with the recent theoretical work in a fully microscopic fermionic molecular dynamics approach and a few other representative calculations emphasize the need for further experimental as well as theoretical work to resolve the existing conflicts. The cross section of the 3 He(α, γ ) 7 Be direct capture reaction was first studied by Holmgren et al. [1], being followed by a posteriori measurements of solar fusion reactions of ever-increasing sophistication and accuracy. These measurements are driven by the need to obtain more precise information that is crucial for a critical evaluation of solar models, solar neutrino fluxes, and big-bang nucleosynthesis (BBN) [2][3][4]. Specifically, the 3 He(α, γ ) 7 Be reaction plays a key role in calculating the high-energy solar neutrino flux that probes the temperature as well as the metallicity of the solar interior [3] and in explaining the primordial 7 Li abundances [4]. In recent years, the so-called 7 Li problem has attracted a considerable amount of attention as the disagreement between the observations and the predictions of the primordial 7 Li abundances became worse resulting in a persistent discrepancy of a factor of 3. This open problem poses severe challenges to the cosmological models that have been used for predicting the primordial abundances of nuclei [4][5][6][7]. In Ref.[5], a change of ∼16% was calculated in the central value of 7 Li abundance at BBN energies by utilizing the results from an evaluation of the available data on the astrophysical S 34 factor. This work highlights the need for an accurate knowledge of this reaction rate for reliable predictions of the 7 Li abundance and therefore for any progress towards a solution.There have been a number of efforts on both the experimental and the theoretical fronts that followed Ref. [1], in particular at low energies [8][9][10][11][12][13]. A "best" result of S 34 (0) = 0.56(3) keV b was reported in Ref. [3] from an evaluation of the modern data that became available after 1998 (Ref. [14]) for the energies below 1 MeV. This improved value can be compared with the previous recommendation [14] of 0.53 (5) keV b. Such * snarasingh@gmail.com efforts also suggested that the precision could be improved if the theoretical spread in the extrapolated values is minimized. In addition, recent work of the ERNA (European recoil mass separator for nuclear astrophysics) Collaboration [15] is in conflict with the data from Ref. [8] and highlights the importance of precise measurements at medium energies, ...

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“…Refs. [33,34,35,36,37,38,39,40,41,42,43]). The application of different theoretical models introduces a non-negligible uncertainty in the extrapolated S-factor.…”

Section: Introductionmentioning

confidence: 99%

Activation measurement of the reaction cross section at high energies

et al. 2013

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The astrophysically important 3 He(α, γ) 7 Be reaction was studied at high energies where the available experimental data are in contradiction. A thin window 3 He gas cell was used and the cross section was measured with the activation method. The obtained cross sections at energies between E c.m. = 1.5 and 2.5 MeV are compared with the available data and theoretical calculations. The present results support the validity of the high energy cross section energy dependence observed by recent experiments.

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Low-energyHe3(α,α)He3

Cited by 32 publications

References 62 publications

Microscopic Nuclear Structure and Reaction Calculations in the FMD Approach

Microscopic Nuclear Structure and Reaction Calculations in the FMD Approach

New measurement of the3He(α,γ)7Be cro

Activation measurement of the reaction cross section at high energies

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