For a photon to excite an electron of an atom it typically has to have the exact right amount of energy for the transition. When the photon energy is to low it is pretty clear that the transition can not take place. But also a photon with to much energy seems to have a very low probability of interacting (e.g. the answer to this Question says so:
- the electron [is] in a different atomic orbital (i.e. it's been excited) and a photon with a different energy.
The probability of (3) is generally negligable
But in szintillator materials the incident photon is, at least as far as I understand, doing exactly that. It is exciting one atom after another, always giving away a fraction of its energy and creating a bunch of secondary photons, until the photon is complety absorbed.
Is my understanding of the process wrong? Or where lies the difference between the two described behaviours?