Status of the LUNA experiment

Luna is a pilot project initially focused on We He-3(He-3, 2p)He-4 cross section measurement within the thermal energy region of the Sun (15-27 keV). A compact high current 50 kV ion accelerator facility including a windowless gas target system, a beam calorimeter and four detector telescopes has been built, tested and installed underground at Laboratori Nazionali del Gran Sasso. In these conditions, thanks to the cosmic ray suppression, we could attain a background level of less than 1 event per week, a rate similar to the one expected from He-3(He-3, 2p)He-4 at the lower edge of the Sun thermal energy region.