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Anders, M.; Trezzi, D.; Menegazzo, R.; Aliotta, M.; Bellini, Andrea; Bemmerer, D.; Broggini, C.; Caciolli, A.; Corvisiero, P.; Costantini, H.; Davinson, T.; Elekes, Z.; Erhard, M.; Formicola, A.; Fülöp, Zs.; Gervino, G.; Guglielmetti, A.; Gustavino, C.; Gyürky, Gy.; Junker, M.; Lemut, A.; Marta, M.; Mazzocchi, C.; Prati, P.; Alvarez, C. Rossi; Scott, D. A.; Somorjai, E.; Straniero, O.; Szücs, T.

doi:10.1103/physrevlett.113.042501

Cited by 105 publications

(122 citation statements)

References 33 publications

(85 reference statements)

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“…The 2 H( α, γ ) 6 Li cross section has never been directly measured in the BBN region of interest (30 ࣠ E ࣠ 300 keV), before the LUNA data first reported in [5] . It is worth nothing, only one attempt to directly measure the 2 H( α, γ ) 6 Li cross section at low energy is reported in literature, providing only an upper limit [17] .…”

Section: The Nuclear Physics Of Primordial 6 LImentioning

confidence: 99%

“…(4) is below the calorimeter. The pressure is kept constant by means of a feedback system controlled by a pressure gauge (5). The γ -rays produced by the 2 H( α, γ ) 6 Li reaction are detected by a HPGe detector (6).…”

Section: The Nuclear Physics Of Primordial 6 LImentioning

confidence: 99%

“…The measurement has been carried out with the world's only underground accelerator for nuclear astrophysics, situated at the Laboratori Nazionali del Gran Sasso (LNGS), Italy. The data at center-of-mass energy E = 133 and 93 keV have been previously published in abbreviated form [5] . Here, two new data points at E = 120 and 80 keV are presented.…”

Section: Introductionmentioning

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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Section: The Nuclear Physics Of Primordial 6 LImentioning

confidence: 99%

Section: The Nuclear Physics Of Primordial 6 LImentioning

confidence: 99%

Section: Introductionmentioning

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 few years ago, observations [40] of 6 Li in a few metal poor stars had suggested the presence of a plateau, at typically 6 Li/H ≈ 10 −11 , orders of magnitude higher than the BBN predictions of 6 Li/H ≈ 1.3×10 −14 [41]. The uncertainties on the D(α, γ) 6 Li cross section have been experimentally constraint by a LUNA measurement [42] and by theory [43] confirming the BBN value. However, later, the observational 6 Li plateau has been questioned due to line asymmetries which were neglected in previous abundance analyses.…”

Section: Discussionmentioning

confidence: 72%

Primordial Nucleosynthesis

Coc

2017

Proceedings of the 14th International Symposium on Nuclei in the Cosmos (NIC2016)

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Primordial or big bang nucleosynthesis (BBN) is now a parameter free theory whose predictions are in good overall agreement with observations. However, the 7 Li calculated abundance is significantly higher than the one deduced from spectroscopic observations. Most solutions to this lithium problem involve a source of extra neutrons that inevitably leads to an increase of the deuterium abundance. This seems now to be excluded by recent deuterium observations that have drastically reduced the uncertainty on D/H and also calls for improved precision on thermonuclear reaction rates.

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“…The accelerated deuterium particles, after Rutherford scattering with the α-beam, interact with the gas itself producing the two reactions: 2 H(d,n) 3 He and 2 H(d,p) 3 H. In particular, the neutrons emitted by the 2 H(d,n) 3 He were responsible for a high beam induced background in the γ-spectrum. A long and detailed study of this background was required in order to perform the analysis of the data [58][59][60].…”

Section: Big Bang Nucleosynthesismentioning

confidence: 99%

Nuclear Astrophysics in underground laboratories: the LUNA experiment

Simpson¹,

Simenel²,

Cook³

et al. 2017

EPJ Web Conf.

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Abstract. One of the main ingredients of nuclear astrophysics is the knowledge of the thermonuclear reactions responsible for powering the stellar engine and for the synthesis of the chemical elements. At astrophysical energies the cross section of nuclear processes is extremely reduced by the effect of the Coulomb barrier. The low value of cross sections prevents their measurement at stellar energies on Earth surface and often extrapolations are needed. The Laboratory for Underground Nuclear Astrophysics (LUNA) is placed under the Gran Sasso mountain and thanks to the cosmic-ray background reduction provided by its position can investigate cross sections at energies close to the Gamow peak in stellar scenarios. Many crucial reactions involved in hydrogen burning has been measured directly at astrophysical energies with both the LUNA-50kV and the LUNA-400kV accelerators, and this intense work will continue with the installation of a MV machine able to explore helium and carbon burnings. Based on this progress, currently there are efforts in several countries to construct new underground accelerators. In this talk, the typical techniques adopted in underground nuclear astrophysics will be described and the most relevant results achieved by LUNA will be reviewed. The exciting science that can be probed with the new facilities will be highlighted.

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First Direct Measurement of theH2(α,γ)Li

Cited by 105 publications

References 33 publications

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

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

Primordial Nucleosynthesis

Nuclear Astrophysics in underground laboratories: the LUNA experiment

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