Study of the proton-induced reactions on 19F at LUNA

First-generation (Pop. III) stars evolve differently from later stellar generations due to their primordial composition. The initial absence of carbon, oxygen, and nitrogen requires higher core temperatures to ignite the triple-alpha (3) process and initiate the CNO cycle. Although calcium production in these stars was traditionally attributed to advanced nuclear burning and supernovae, this explanation contradicts observed abundance trends. A potential explanation is a breakout from the CNO cycle under high-temperature H-burning conditions, specifically through the 19F(, )20Ne reaction route. A recent direct measurement of this reaction at the Jinping Underground Nuclear Astrophysics (JUNA) experiment in China revealed a higher cross-section than previously reported, potentially explaining the enhanced calcium observed in ultra iron-poor stars. A second direct measurement is being conducted at the LUNA facility in Gran Sasso National Laboratory (LNGS), Italy, taking advantage of its low-background underground environment, aiming to improve the JUNA results. In this campaign, the first batch of beamtime was focused on studying the stability of fluorine targets under intense beam irradiation, while the second phase will concentrate on cross-section measurements. This thesis presents a detailed study of the 19F(α, γ)20Ne reaction, aiming to measure its branching ratios and cross-section at astrophysically relevant energies with high precision.