Few-Body Resonances in Light Nuclei

Csótó, Attila

doi:10.1007/978-3-7091-6114-2_12

Cited by 28 publications

(58 citation statements)

References 42 publications

(59 reference statements)

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“…However, the slope has been questioned [26] for E ≤ 300 keV, where there are no high-precision data. Furthermore, a global analysis [3] indicates that S-factor data obtained with the activation method are systematically higher than the prompt-γ results.…”

Section: Thementioning

confidence: 99%

“…Previous activation studies [15,16,17,18] cover the energy range E = 420-2000 keV. Prompt γ-ray measurements [15,19,20,21,22,23,24] cover E = 107-2500 keV, although with limited precision at low energies.The global shape of the S-factor curve is well reproduced by theoretical calculations [25,26]. However, the slope has been questioned [26] for E ≤ 300 keV, where there are no high-precision data.…”

mentioning

confidence: 90%

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Activation Measurement of theHe3(α,γ)Be7Cross Section at Low Energy

Bemmerer¹,

Confortola²,

Costantini³

et al. 2006

Phys. Rev. Lett.

146

208

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The nuclear physics input from the 3 He(α, γ) 7 Be cross section is a major uncertainty in the fluxes of 7 Be and 8 B neutrinos from the Sun predicted by solar models and in the 7 Li abundance obtained in big-bang nucleosynthesis calculations. The present work reports on a new precision experiment using the activation technique at energies directly relevant to big-bang nucleosynthesis. Previously such low energies had been reached experimentally only by the prompt-γ technique and with inferior precision. Using a windowless gas target, high beam intensity and low background γ-counting facilities, the 3 He(α, γ) 7 Be cross section has been determined at 127, 148 and 169 keV center-of-mass energy with a total uncertainty of 4 %. The sources of systematic uncertainty are discussed in detail. The present data can be used in big-bang nucleosynthesis calculations and to constrain the extrapolation of the 3 He(α, γ) 7 Be astrophysical S-factor to solar energies. The 3 He(α, γ) 7 Be reaction is a critical link in the 7 Be and 8 B branches of the proton-proton (p-p) chain of solar hydrogen burning [1]. At low energies its cross section σ(E) (E denotes the center of mass energy, E α the 4 He beam energy in the laboratory system) can be parameterized by the astrophysical S-factor S(E) defined as. The 9.4 % uncertainty [3] in the Sfactor extrapolation to the solar Gamow energy (23 keV) contributes 8 % to the uncertainty in the predicted fluxes of solar neutrinos from the decays of 7 Be and 8 B [4]. The interior of the Sun, in turn, can be studied [4,5] by comparing this prediction with the data from neutrino detectors [6,7], which determine the 8 B neutrino flux with a total uncertainty as low as 3.5 % [7].Furthermore, the production of 7 Li in big-bang nucleosynthesis (BBN) is highly sensitive to the 3 He(α, γ) 7 Be cross section in the energy range E ≈ 160-380 keV [8], with an adopted uncertainty of 8 % [9]. Based on the baryon-to-photon ratio from observed anisotropies in the cosmic microwave background [10], network calculations predict primordial 7 Li abundances [11] that are significantly higher than observations [12,13]. A lower 3 He(α,γ)7 Be cross section at relevant energies may explain part of this discrepancy. The3 He(α,γ) 7 Be (Q-value: 1.586 MeV) reaction leads to the emission of prompt γ-rays, and the final 7 Be nucleus decays with a half-life of 53.22 ± 0.06 days, emitting a 478 keV γ-ray in 10.44 ± 0.04 % of the cases [14]. The cross section can be measured by detecting either the induced 7 Be activity (activation method) or the prompt γ-rays from the reaction (prompt-γ method). Previous activation studies [15,16,17,18] cover the energy range E = 420-2000 keV. Prompt γ-ray measurements [15,19,20,21,22,23,24] cover E = 107-2500 keV, although with limited precision at low energies.The global shape of the S-factor curve is well reproduced by theoretical calculations [25,26]. However, the slope has been questioned [26] for E ≤ 300 keV, where there are no high-precision data. Furthermore, a global analysis [3] ind...

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Section: Thementioning

confidence: 99%

mentioning

confidence: 90%

Activation Measurement of theHe3(α,γ)Be7Cross Section at Low Energy

Bemmerer¹,

Confortola²,

Costantini³

et al. 2006

Phys. Rev. Lett.

146

208

View full text Add to dashboard Cite

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“…Owing to the extremely low background conditions of the underground laboratory, the cross section has been measured at low energies never reached before. The details of the experiment have Kajino and Arima [22] 0.547 ± 0.017 1.12 Csótó and Langanke [23] 0.586 ± 0.018 1.47 Descouvemont et al [24] 0.550 ± 0.017 1.11 NACRE [26] 0.597 ± 0.019 2.02 been discussed elsewhere [19,20,21]. In the first phase of the experiment the cross section was measured with the activation technique at energies of 106, 127, 148 and 169 keV.…”

Section: "Modern" Measurements Ofmentioning

confidence: 99%

“…[25] was adopted. For the model of Csótó and Langanke [23] linear energy dependence of the S factor was supposed in the considered low energy range adopting the slope of the S factor curve given in Table 1. of Ref.…”

Section: Zero Energy Extrapolation Of the Luna Activation Datamentioning

confidence: 99%

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Comparison of the LUNA³He(α, γ)⁷Be activation results with earlier measurements and model calculations

Gyürky

Bemmerer

Confortola

et al. 2007

J. Phys. G: Nucl. Part. Phys.

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Abstract. Recently, the LUNA collaboration has carried out a high precision measurement on the 3 He(α, γ) 7 Be reaction cross section with both activation and online γ-detection methods at unprecedented low energies. In this paper the results obtained with the activation method are summarized. The results are compared with previous activation experiments and the zero energy extrapolated astrophysical S factor is determined using different theoretical models.

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