Scintillators:

Organic scintillators:
Fast, but poor light yield.
Binary or ternary systems consisting of:

Mechanism: the incident particle excites the solvent; this transfers the excitation to the solute (e.g. through dipole interactions) and this in turns produces the signal.
Without the solute, the base material would re-absorb the light before it's efficiently collected.
The process of excitation, molecular transfer, and light emission is very fast (~ a few nanoseconds).

Inorganic scintillators:
Higher light yield (and so better resolution) but slower.
Also better signal linearity.
One drawback is that they are not intrinsically uniform. It's very difficult to grow very uniform crystals, and to have identical crystals.
Uniformity is of paramount importance for materials with small light yield (e.g. PbWO4)
In order to increase the light yield, for example by matching the signal wavelenght to the maximum sensitivity of the photocatode, and to obtain a faster response, crystal can be doped (e.g. with Tl), in order to create additional activation sites in the gap between valence and conduction bands.