Speaker
Description
The energy production, chemical evolution and elemental abundances of stars are governed by thermonuclear reactions occurring at energies far below the Coulomb barrier. Measuring their cross sections is the central challenge of experimental nuclear astrophysics: at stellar energies the Coulomb repulsion suppresses the cross sections by many orders of magnitude, down to the picobarn-femtobarn range, so that cosmic-ray and environmental backgrounds become the limiting factor. At LUNA (Laboratory for Underground Nuclear Astrophysics), located under 1400~m of rock at the INFN Gran Sasso National Laboratory (Italy), the cosmic-ray background is suppressed by several orders of magnitude, making it possible to reproduce in the laboratory the reactions that take place in stars. I will introduce the LUNA project and its role in astrophysics through a selection of landmark measurements. I will then focus on two crucial reactions of the CNO cycle: 19F(p,ag)16O and 19F(p,g)20Ne. The ratio between the two channels determines whether material is recycled within the CNO cycle or leaks towards the Ne-Na region, with consequences for the fluorine abundance and for the nucleosynthesis in AGB stars, massive stars and novae. I will present the recent results for the (p,ag) channel. Finally, I will outline the scientific perspectives of LUNANOVA, the recently awarded ERC Synergy Grant, which will open new frontiers for underground nuclear astrophysics.