water and about 1,000 photomultiplier tubes (PMTs) attached to its inner surface. The detector was upgraded, starting in 1985, to allow it to observe solar neutrinos. As a result, the detector (KamiokaNDE-II) had become sensitive enough to detect neutrinos from SN 1987A, a supernova which was observed in the Large Magellanic Cloud in February 1987, and to observe solar neutrinos in 1988. The ability of the Kamiokande experiment to observe the direction of electrons produced in solar neutrino interactions allowed experimenters to directly demonstrate for the first time that the Sun was a source of neutrinos. The Super-Kamiokande project was approved by the Japanese Ministry of Education, Science, Sports and Culture in 1991 for total funding of approximately $100 M. The US portion of the proposal, which was primarily to build the OD system, was approved by the US Department of Energy in 1993 for $3 M. In addition, the US has also contributed about 2000 20 cm PMTs recycled from the IMB experiment. Despite successes in neutrino astronomy and neutrino astrophysics, Kamiokande did not achieve its primary goal, the detection of proton decay. Higher sensitivity was also necessary to obtain high statistical confidence in its results. This led to the construction of Super-Kamiokande, with fifteen times the water and ten times as many PMTs as Kamiokande. Super-Kamiokande started operation in 1996. The Super-Kamiokande Collaboration announced the first evidence of neutrino oscillation in 1998. This was the first experimental observation supporting the theory that the neutrino has non-zero mass, a possibility that theorists had speculated about for years. The 2015 Nobel Prize in Physics was awarded to Super-Kamiokande researcher Takaaki Kajita alongside Arthur McDonald at the Sudbury Neutrino Observatory for their work confirming neutrino oscillation. On 12 November 2001, about 6,600 of the photomultiplier tubes (costing about $3000 each) in the Super-Kamiokande detector imploded, apparently in a chain reaction or cascading failure, as the shock wave from the concussion of each imploding tube cracked its neighbours. The detector was partially restored by redistributing the photomultiplier tubes which did not implode, and by adding protective acrylic shells that are hoped will prevent another chain reaction from recurring (Super-Kamiokande-II). In July 2005, preparations began to restore the detector to its original form by reinstalling about 6,000 PMTs. The work was completed in June 2006, whereupon the detector was renamed Super-Kamiokande-III. This phase of the experiment collected data from October 2006 till August