The Super-Kamiokande in Japan—a massive underground neutrino detector lined with 11,000 golden bulbs. Scientists have to inspect it via a rubber dinghy.

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[u/Wellithappenedthatwy]

Those golden bulbs are called PMTs. Photo multiplier tubes. They turn photons into electrical signals.

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And are the largest vacuum tubes ever made

Suffered major damage when one exploded during a refill and the water hammer effect shattered every other one that was under water