A popular theory had arisen in the 1980s that protons could decay, just as atoms and isotopes. In order to determine if the theory was correct, the Japanese held an experiment, lead by Masatoshi Koshiba, and built a large tank of water surrounded with detectors on the edge to search for decaying protons. The experiment was called Kamiokande, for the Kamioka Nucleon Decay Experiment.
The Water Tank (encompassed with detectors)
The tank held approximately 3000 metric tons of water in it, or about 10^34 protons. After running for one year, the detector did not find any protons to have decayed. Since every proton had been observed for 1 year, and there were 10^34 years, it was observed that the protons lived at least for 10^34 years without decaying – longer than the life of the universe (10^10 years). These findings proved the theory false..but that wasn’t the lucky discovery.
In 1987, a supernova exploded in the Large Magellanic Cloud. It was the first time any event so destructive and energetic occurred relatively close to the earth since recorded history. The experiment happened to be running at the time — and the detectors went off in relation to 11 events, all near the source of the supernova.
The Detector Display from the Water Tank
Koshiba’s Nucleon Decay Experiment had just functioned as a Neutrino Detector Experiment, one he had surprisingly been working on with seemingly no relation to his government authorized nucleon experiment. As the detectors had still been running when the supernova exploded, Koshiba and his team had remarkably detected the first astrophysical neutrinos from anything other than the Sun – fitting in perfectly with his second analysis regarding neutrinos.
For his lucky discovery and resulting work regarding neutrinos, Koshiba won the Nobel Prize in 2002. The work that grew out of the astounding results led directly to the discovery of neutrino oscillations and the fact that neutrinos have mass.
Although Koshiba was a brilliant man with vast amounts of knowledge on particle physics, the detectors fortunately running at the exact moment of the supernova explosion resulted in a lucky discovery regarding neutrinos that awarded him the Nobel Prize.