Laboratory Underground for Nuclear Astrophysics New Observatory for Solar Neutrino Reactions

Objective

Nuclear astrophysics studies the processes that generate energy and control the chemical makeup of the universe. One area of nuclear astrophysics has recently entered the 1% precision domain: Big Bang nucleosynthesis. However, another area of nuclear astrophysics with even greater importance is still lagging behind: Our Sun. Here, the precision breakthrough is still missing, and hampering not only the solar but all stellar models. LUNANOVA ideally combines a great effort from nuclear experiment, theory, and astrophysics: The results of astrophysical simulations guide the nuclear physics work and the nuclear physics data feed new simulations. LUNANOVA will transform the understanding of hydrogen burning, in our Sun but also in other stars, from the 10% to the 1% precision level. We will install and operate a new, dedicated underground ion accelerator for solar fusion, LUNANOVA, at the INFN Gran Sasso lab. LUNANOVA is complementary to the Bellotti Ion Beam Facility for helium and carbon burning that was inaugurated in 2023. Coupled with additional experiments in Germany and Italy, the LUNANOVA data will be used to develop novel models of the Sun and solar-like stars. In a close and continuous symbiosis of experiments and models, we will target our efforts at the decisive node: nuclear processes located at a place in the nuclear lifecycle of the star that breaks the degeneracy between energy production and nucleosynthesis. These processes shall be studied in the laboratory. The lab data shall feed into the solar and stellar models, which, in turn, will give predictions on helioseismology and solar neutrino fluxes that can be matched with observation. LUNANOVA will include the entire knowledge and discovery cycle. The sustained, long-term synergy between LUNANOVA experiments, ancillary experimental and theoretical studies elsewhere, and detailed astrophysical modeling will deliver the needed breakthrough for our Sun and for nuclear astrophysics.