Cherenkov Radiation
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Cherenkov radiation is the blue glow when particles exceed light's speed in a medium.
The IAEA article explains Cherenkov radiation: a blue or violet glow emitted when charged particles travel faster than light in a medium like water. In water, light slows to about 75% of its vacuum speed, enabling particles like neutrinos to outpace it. This effect is used in detectors such as IceCube and atmospheric Cherenkov telescopes.
What commenters are saying
Commenters expanded on applications: cosmic ray detectors like Pierre Auger Observatory use Cherenkov light in water tanks, and neutrino telescopes like IceCube detect flashes in Antarctic ice. They clarified the effect occurs in any medium, not just water, and debated whether the title was misleading. Some noted Cherenkov radiation is directional, unlike isotropic scintillation, aiding particle reconstruction.