LUNA particle detector. LUNA (the Laboratory for Underground Nuclear Astrophysics) is part of the Gran Sasso National Laboratory (LNGS), inside the Gran Sasso mountain, Abruzzo, Italy. The mountain shields the LNGS experiments from outside radiation, allowing particle physicists and astrophysicists to study rare interactions involving neutrinos and other particles. The LUNA experiments study nuclear reactions in stars that generate energy and new elements, looking at a relatively narrow energy window called the Gamow peak.