Cherenkov Radiation? What is That?

Can you travel faster than light? The answer might shock you.

Cherenkov radiation from spent nuclear rods in a pool

Looks like a clickbait title, right? Well, the answer is, it depends. For all you nerds out there, nothing travels faster than the speed of light according to the theory of special relativity. Well, nothing travels faster than the speed of light in a vacuum, which is about 300000 km/s.

However, in other media, traveling faster than light is possible. This is due to the fact that light is slowed down as it travels in dense media. In such density, we find that some particles travel faster than the speed of light hence the Cherenkov radiation phenomenon.

The Definition

Cherenkov radiation refers to electromagnetic radiation that is emitted when a charged particle travels in a dielectric, at a velocity higher than the phase velocity of light in that medium.

Since the speed of light in a dielectric is slower than that of light in a vacuum, special relativity

is not violated. The phenomenon was named after Russian scientist, Pavel Cherenkov, who observed

this experimentally.

Whenever a plane travels faster than the speed of sound, a sound boom occurs. Well, Cherenkov

radiation is to light what sonic boom is to sound. The radiation is in the form of a bluish tint of light,

which is observed in most open pool nuclear reactors, or vitreous humor of eyes. The Cherenkov light is responsible for the blue shade of the pools where the very radioactive spent fuel of nuclear power plants is stored.

The cladding enclosing the fuel rods are leakproof and thick enough to stop the beta rays of radioactive decays. On the other hand, they let some gamma rays penetrate the storage pool.

Interacting with water this gamma will produce electrons by Compton effect. If they are fast enough,

these electrons will produce a flash of blue light by the Cherenkov effect. Compton scattering is a

phenomenon we will deal with later (to keep you on your toes, it is responsible for the sky being blue).

Why did I tell you this?

Maybe so that you may flex on your friends who say that nothing travels faster than the speed of light. Maybe as a piece of knowledge you may want to add to your archives.

Well, where is it used? In the detection of biomolecules, which are injected with radioactive isotopes, medical imaging, in nuclear reactors to signify the presence of spent nuclear rods ( do not enter a pool that is glowing blue in a nuclear power plant, thank me later).

It is also used to detect cosmic radiation, and give direction of travel of gamma rays during cosmic showers.

In conclusion, Cherenkov radiation is emitted when charged particles with mass travel faster than the speed of light in a particular medium, producing an equivalent of a sonic boom for light. Now go wild and spread the tidings. Till next time. Ciao.