14N(p,γ)15O at LUNA-400 kV
PIs: Francesca Cavanna, Rosanna Depalo
Astrophysical Motivation
Solar neutrinos play a significant role in constraining physical conditions in the interior of the Sun and are a unique tool to investigate its core composition. Borexino has just opened the era of CNO neutrinos detection, obtaining for the first time a 5-sigma direct experimental evidence for a non-vanishing flux from the Sun. Combined with precise thermonuclear cross section measurements, they can be used to determine the metallicity of our Sun and solve the Solar composition problem. As a matter of fact, the 14N(p,γ)15O cross section is the dominant error source on neutrino flux predictions. At solar energies (15 - 50 keV) such a
cross section is too low to be measured directly. Therefore, current estimates are based on extrapolations of higher-energy data.
Experimental Aims
In the framework of the PRIN 2022 project SOCIAL (SOlar Composition Investigated At Luna), we aim at determining the 14N(p,γ)15O cross section with 5% precision, measuring the contributions from individual 15O excited states at center-of-mass-energies between 100 and 370 keV and addressing all the debated transitions.
Experimental setup
The measurement is ongoing at the solid target station; gamma rays have been detected with a high-efficiency 4π-BGO detector composed by 6 independent segments. We have installed a dedicated data acquisition system and developed a new data analysis technique to determine partial cross sections for individual gamma transitions, despite the poor energy resolution of the BGO detector. Such a technique foresees the use of gamma-gamma coincidences and a detailed comparison of experimental and simulated spectra.