The production of the stable isotope 6Li in standard Big Bang nucleosynthesis has recently attracted much interest. Recent observations in metal-poor stars suggest that a cosmological 6Li plateau may exist. If true, this plateau would come in addition to the well-known Spite plateau of 7Li abundances and would point to a predominantly...
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2013 (v1)PublicationUploaded on: March 27, 2023
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2012 (v1)Publication
Classical novae are important contributors to the abundances of key isotopes, such as the radioactive 18F, whose observation by satellite missions could provide constraints on nucleosynthesis models in novae. The 17O(p,gamma)18F reaction plays a critical role in the synthesis of both oxygen and fluorine isotopes but its reaction rate is not...
Uploaded on: July 3, 2024 -
2012 (v1)Publication
Classical novae are important contributors to the abundances of key isotopes, such as the radioactive 18F, whose observation by satellite missions could provide constraints on nucleosynthesis models in novae. The 17Oðp; Þ18F reaction plays a critical role in the synthesis of both oxygen and fluorine isotopes, but its reaction rate is not well...
Uploaded on: May 13, 2023 -
2018 (v1)Publication
When deriving resonance strengths using the thick-target yield approximation, for very narrow resonances it may be necessary to take beam energy straggling into account. This applies to gas targets of a few keV width, especially if there is some additional structure in target stoichiometry or detection efficiency. The correction for this effect...
Uploaded on: April 14, 2023 -
2015 (v1)Publication
We report on measurements of resonance strengths and energies for the Ep = 151 and 193 keV resonances in the 18O(p,gamma)15N and 17O(p,gamma)14N reactions, respectively, obtained during commissioning of a new setup for alpha-particle detection studies at the LUNA underground laboratory. Our values, omegagamma(151) = 164.2 ± 0.9 stat+12.1−11.7...
Uploaded on: April 14, 2023 -
2014 (v1)Publication
The 22Ne(p,gamma)23Na reaction takes part in the neon-sodium cycle of hydrogen burning. This cycle is active in asymptotic giant branch stars as well as in novae and contributes to the nucleosythesis of neon and sodium isotopes. In order to reduce the uncertainties in the predicted nucleosynthesis yields, new experimental efforts to measure the...
Uploaded on: April 14, 2023 -
2012 (v1)Publication
The direct measurement of reaction cross sections at astrophysical energies often requires the use of solid targets of known thickness, isotopic composition, and stoichiometry that are able to withstand high beam currents for extended periods of time. Here, we report on the production and characterisation of isotopically enriched Ta2O5 targets...
Uploaded on: April 14, 2023 -
2019 (v1)Publication
The 18O(p,α)15N reaction affects the synthesis of 15N, 18O and 19F isotopes, whose abundances can be used to probe the nucleosynthesis and mixing processes occurring deep inside asymptotic giant branch (AGB) stars. We performed a low-background direct measurement of the 18O(p,α)15N reaction cross-section at the Laboratory for Underground...
Uploaded on: March 27, 2023 -
2018 (v1)Publication
The 22Ne(p,γ)23Na reaction, part of the neon-sodium cycle of hydrogen burning, may explain the observed anticorrelation between sodium and oxygen abundances in globular cluster stars. Its rate is controlled by a number of low-energy resonances and a slowly varying nonresonant component. Three new resonances at Ep = 156.2, 189.5, and 259.7 keV...
Uploaded on: April 14, 2023 -
2019 (v1)Publication
The observation of oxygen isotopes in giant stars sheds light on mixing processes operating in their interiors. Due to the very strong correlation between nuclear burning and mixing processes it is very important to reduce the uncertainty on the cross sections of the nuclear reactions that are involved. In this paper we focus our attention on...
Uploaded on: April 14, 2023 -
2018 (v1)Publication
The experimental study of nuclear reactions of astrophysical interest is greatly facilitated by a low-background, high-luminosity setup. The Laboratory for Underground Nuclear Astrophysics (LUNA) 400 kV accelerator offers ultra-low cosmic-ray induced background due to its location deep underground in the Gran Sasso National Laboratory...
Uploaded on: March 27, 2023 -
2022 (v1)Publication
nstars,the fusion of 22Ne and4Hemayproduce either 25Mg, with the emission of a neutron, or 26Mg and a γ ray. At hightemperature, the (α,n)channeldominates,while at low temperature, it is energetically hampered. The rate of its competitor, the 22Ne(α,γ)26Mg reaction, and, hence, the minimum temperature for the (α,n) dominance, are controlled by...
Uploaded on: February 22, 2023 -
2020 (v1)Publication
The astrophysical 6Li(p, γ ) 7Be reaction occurs during Big Bang nucleosynthesis and the pre-main sequence and main sequence phases of stellar evolution. The low-energy trend of its cross section remains uncertain, since different measurements have provided conflicting results. A recent experiment reported a resonance like structure at...
Uploaded on: April 14, 2023