The synthesis of Ne, Na, Mg, and Al isotopes is connected to the NeNa-MgAl cycles of stellar burning. The entire cycle speed is controlled by the 20Ne(p,gamma)21Na reaction (Qvalue=2431.68 keV) which is the first and slowest reaction of the whole NeNa cycle. At the state of the art, the associated reaction rate uncertainty therefore affects the production of the elements in the NeNa cycle and their yields in various stellar environments. In the relevant temperature range from 0.1 GK to 1 GK, the rate is mainly dominated by the 366 keV resonance, corresponding to the excited state of Ex= 2797.5 keV, and by the direct capture component. The present thesis analyses the direct capture below energies of 400 keV, which has been studied in deep underground at LUNA (Laboratory for Underground Nuclear Astrophysics), located at Gran Sasso National Laboratories in Italy. The reaction has been measured using the intense proton beam delivered by the LUNA 400 kV accelerator and a windowless differentially pumped gas target filled with natural neon at pressure of few mbar. Two high-purity germanium detectors collected the photons produced in the reaction, obtaining detailed gamma spectra. This work will present the experimental details of the campaign and its scientific results, focusing on the 20Ne(p,gamma)21Na cross section at stellar energies and its possible impact on the associated thermonuclear reaction rate.
Studio della reazione 2ONe(p,γ)21Na a LUNA
BARBIERI, LUCIA
2021/2022
Abstract
The synthesis of Ne, Na, Mg, and Al isotopes is connected to the NeNa-MgAl cycles of stellar burning. The entire cycle speed is controlled by the 20Ne(p,gamma)21Na reaction (Qvalue=2431.68 keV) which is the first and slowest reaction of the whole NeNa cycle. At the state of the art, the associated reaction rate uncertainty therefore affects the production of the elements in the NeNa cycle and their yields in various stellar environments. In the relevant temperature range from 0.1 GK to 1 GK, the rate is mainly dominated by the 366 keV resonance, corresponding to the excited state of Ex= 2797.5 keV, and by the direct capture component. The present thesis analyses the direct capture below energies of 400 keV, which has been studied in deep underground at LUNA (Laboratory for Underground Nuclear Astrophysics), located at Gran Sasso National Laboratories in Italy. The reaction has been measured using the intense proton beam delivered by the LUNA 400 kV accelerator and a windowless differentially pumped gas target filled with natural neon at pressure of few mbar. Two high-purity germanium detectors collected the photons produced in the reaction, obtaining detailed gamma spectra. This work will present the experimental details of the campaign and its scientific results, focusing on the 20Ne(p,gamma)21Na cross section at stellar energies and its possible impact on the associated thermonuclear reaction rate.File | Dimensione | Formato | |
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https://hdl.handle.net/20.500.12608/34462