π Argentina's massive water tanks catch cosmic rays π
Argentina began using 1,660 water tanks in 2004 to detect powerful cosmic rays. The Pierre Auger Observatory is located across 3,000 square kilometres of western Argentina. These surface detectors use tanks filled with 12,000 litres of ultra-pure water each, with three photomultiplier tubes above them. This setup measures secondary particles from air showers caused by high-energy cosmic rays hitting the atmosphere. Scientists use this hybrid system to study particle energies and composition, investigating extreme cosmic events.