Cherenkov radiation was first observed by Marie and Pierre Currie in the early part of the twentieth century. The effect was named after Pavel Alekseyevich Cherenkov, who in 1958 won the Nobel Prize for being the first to rigorously characterize it:

This electromagnetic radiation is caused by charged particles moving through a dielectric material with a speed, v_c , that is greater than that of light in the matter:

where v_L is the speed of light in the medium, c is the speed of light in a vacuum and n(l) is the index of refraction. These particles are referred to as being superluminal. One common analogy is to the effect of a sonic boom, the light forms a similar shock wave cone emanating from the location of the charged particle.
         The molecules or atoms of the dielectric become polarized by the charged particles. When the newly created dipoles return to their ground states they emit light mainly in the visible to near UV range. This effect causes the characteristic blue glow seen in pictures of nuclear facilities' water tanks:

Normally the light emitted by such excited atoms or molecules would interfere destructively causing no detectable radiation. However, since the particles in the case of Cherenkov radiation are moving faster than light the photons form a coherent wavefront at a constant angle of q:

The angle is governed by the equation:

where b is the ratio of the speed of the particle, v_c, to the speed of light, c is the speed of light in a vacuum, 299 792 458 m/s, and DT is the elapsed time. In the limit where particle speeds approach c the angle approaches:

As a result of this angle relation, it is required that:

for the radiation to occur, where this minimum value would correspond to the light traveling in the same direction as the particle.

         The differential number of photons produced per unit path length, between the wavelengths of l₂ and l₁, is given by the formula:

From this equation it can be seen that N is proportional to 1/l² and so the light emitted is predominantly in the UV range, peaking in the vicinity of 330 nm.