3.2.5 Scintillation detectors

Scintillation counters consist of a scintillator crystal and a photomultiplier. An incident x-ray photon interacts with the material of the scintillation crystal and produces a spark of light (scintillation). These photons of visible light induce the ejection of electrons from the photocathode of the attached photomultiplier (photo-effect). The ejected electrons imping in successive dynodes of the photomultiplier and their quantity multiplies leading to a final electron cloud that strikes the anode. This induces a negative voltage pulse as output, with amplitude proportional to the energy of the incident photon. Scintillation counters are widely used in gamma ray spectrometry.

Scintillation detectors are preferred to detect shorter wavelengths (K spectra from Niobium (41) – Iodium (53) and L spectra from Thorium (90) – Uranium (92)).