Forest Scintillators
- Scintillation
- the process by which atoms or molecules of a material are given enough energy by an incident particle of radiation to "excite" the system where upon its relaxation to a lower energy state is accomplished through the emission of light.
In general, most materials are capable of scintillating.
It takes about 10^{-9} s ( 1 ns) for an atom to de-excite by giving off light. Atoms can , however, loose there energy by colliding with other atoms. Atoms which collide on time scales less than 1 ns could loose their energy via the collision instead of through the emmission of light.
At standard temperature and pressure, air has a velocity of about
and a mean free path (distance between collisions) of 0.3 nm
this means the time between air molecule collision is about
This air can loose its energy via collisions instead of through the emmision of light.
The situation for your average solid isn't much better
An atom in a solid can collide with 10 other atoms before loosing energy by emmitting a photon.