Qualla: Super-Kamiokande

Super-Kamiokande: Introduction

Mon, 16 Feb 2026 00:00:00 GMT

Photo credit Motokoka, CC BY-SA 4.0. Imagine a cavern the size of a cathedral, hollowed from the rock of a former zinc mine a full kilometer beneath the Japanese Alps. Now fill it with 50,220 tonnes of the purest water on Earth. Line the walls with 11,146 hand-blown glass bulbs, each one a photomultiplier tube exquisitely sensitive to the faintest flash of light. Seal it in darkness. Then wait. This is Super-Kamiokande -- Super-K to the physicists who built it -- and since 1996 it has been watching for events so rare that most of the universe passes through its walls unnoticed. Located under Mount Ikeno near the city of Hida in Gifu Prefecture, it is the world's largest underground neutrino detector, and the discoveries it has made have fundamentally altered our understanding of matter itself.

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Image: Motokoka | CC BY-SA 4.0

Super-Kamiokande: Blue Light in the Deep

Mon, 16 Feb 2026 00:00:00 GMT

Photo credit Daderot, CC0. Super-K works by exploiting a phenomenon called Cherenkov radiation -- the optical equivalent of a sonic boom. When a neutrino, arriving from the Sun or the atmosphere or a distant supernova, interacts with a water molecule inside the tank, it can produce a charged particle that ...

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Image: Daderot | CC0

Super-Kamiokande: From Kamioka to Super-K

Mon, 16 Feb 2026 00:00:00 GMT

Photo credit Joe Haythornthwaite (nagualdesign), CC BY-SA 4.0. The story begins in 1982, when the University of Tokyo's Institute for Cosmic Ray Research started construction on a detector called KamiokaNDE -- Kamioka Nucleon Decay Experiment -- inside the Mozumi Mine. Its original purpose was to catch protons in the act of decaying, a predi...

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Image: Joe Haythornthwaite (nagualdesign) | CC BY-SA 4.0

Super-Kamiokande: The Mass of Nothing

Mon, 16 Feb 2026 00:00:00 GMT

Photo credit 日:Jnn, CC BY 2.1 jp. In 1998, Super-Kamiokande delivered one of the most important results in the history of particle physics. By counting atmospheric neutrinos -- secondary cosmic rays produced when protons from deep space slam into the upper atmosphere -- the team discovered that muon neutrinos tra...

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Image: 日:Jnn | CC BY 2.1 jp

Super-Kamiokande: Catastrophe and Resurrection

Mon, 16 Feb 2026 00:00:00 GMT

Photo credit Joe Haythornthwaite (nagualdesign), CC BY-SA 4.0. On November 12, 2001, disaster struck. A single photomultiplier tube, probably near the bottom of the water-filled tank, imploded. The shock wave from the implosion cracked a neighboring tube, which imploded in turn, and within seconds a chain reaction had destroyed approximately...

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Image: Joe Haythornthwaite (nagualdesign) | CC BY-SA 4.0

Super-Kamiokande: Sentinel of the Galaxy

Mon, 16 Feb 2026 00:00:00 GMT

Photo credit Joe Haythornthwaite (nagualdesign), CC BY-SA 4.0. Super-Kamiokande is not only an instrument for studying known physics. It is a sentinel, watching for rare events that may never come. It continues to search for proton decay, setting a lower bound on the proton's half-life at 5.9 times 10 to the 33rd years for certain decay chan...

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Image: Joe Haythornthwaite (nagualdesign) | CC BY-SA 4.0