...One of the earliest uses of nondestructive investigation was a joint US and Egyptian project to uncover chambers in the Second Pyramid at Giza belonging to Khafre. In 1965, a scientific proposal was submitted to a group of Egyptian physicists and archaeologists using cosmic-ray detectors (nuons technology). The American team, led by Dr. Luis Alvarez, suggested that, since there were two chambers in the superstructure of Khufu's Great Pyramid, and also two in the pyramid of his father, Sneferu, there should also be chambers located in the superstructure of Khafre's pyramid, who was Khufu's son...The Joint Pyramid Project was established...