GALLEX or Gallium Experiment was a radiochemical neutrino detection experiment that ran between 1991 and 1997 at the Laboratori Nazionali del Gran Sasso (LNGS). This project was performed by an international collaboration of French, German, Italian, Israeli, Polish and American scientists led by the Max-Planck-Institut für Kernphysik Heidelberg.
It was designed to detect solar neutrinos and prove theories related to the Sun's energy creation mechanism. Before this experiment, there had been no observation of low energy solar neutrinos.
Read more about GALLEX: Location, Detector, Results, Other Experiments