This gigantic 50,000-ton “ring-imaging water cerenkov detecto”, located underground at the Kamioka Mozumi mine in japan, is used to detect “neutrinos, proton decay and cosmic rays.” Click here for first picture in gallery.

…clever people built the machine to detect cosmic rays: this is done using the 12’000-ish photomultiplier tubes (extremely sensitive light detectors) visible on all walls of the ‘ultra-purified water-filled’ tank

[via deputy-dogTokyo]

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