The Kamiokande observatory, a huge tank of purified water protected from all sources of radiation deep in a mine in Japan, was completed in April, 1983. The purpose of the observatory was to investigate the stability of matter, one of the most fundamental questions of elementary particle physics. The original detector was upgraded in 1985 and renamed Kamiokande II, in order to be sensitive enough to observe elementary particles called neutrinos. This fortuitous decision resulted in the detection of the neutrino blast from a supernova explosion which occurred in the Large Magellanic Cloud in February 1987 (SN 1987A). This facility was built and managed by the Institute for Cosmic Ray Research, University of Tokyo,
What is now the largest neutrino observatory in the world was built in the 1990s in the same mine that holds the original Kamiokande detectors. Super-Kamiokande lies 1,000 meters (3,300 feet) underground. Its huge stainless steel tank, about 41 meters (135 feet) tall and 39 meters (129 feet) across, is filled with ultra-pure water and completely lined with light detectors similar to the one displayed here. In the late 1990s Super-K was the first instrument to collect evidence that led to estimates of the mass of the neutrino. In November 2001, an accident shut down Super-K. Repairs are ongoing.
Adapted from material supplied by the Institute for Cosmic Ray Research, University of Tokyo