Cherenkov

Observatory2 located in Namibia uses five large telescopes to capture and record the faint Cherenkov radiation produced by the heavily charged particles and photons that enter the Earth's atmosphere, producing a shower of particles in their wake.

In this translucent medium, the sensors pick up tiny flashes of so-called Cherenkov radiation that forms when a vanishingly rare neutrino hits the ice and creates a shower of secondary particles.

These faster-than-light events manifest as bright flashes of blue light called Cherenkov radiation.

The fleeing muon will actually exceed the speed of light in water, which is 25% slower than in a vacuum, and generate a shock wave of so-called Cherenkov light, just as a supersonic jet creates a shock wave of sound.

The second array, the Water Cherenkov Detector Array, uses huge water ponds and light-activated scintillators to look for high-energy gamma rays.