A scintillation detector is often portable. The scintillation detector is not as versatile as the GM meter, although it can be used to look for contamination from some radioactive materials. The scintillation detector's active portion for detecting radioactivity is a solid crystal (that is the scintillator) with which the radioactive emission must interact. This essentially limits use of the detector to gamma rays and high-energy beta particles since medium- and low-energy beta particles cannot penetrate the crystal and, therefore, cannot interact.
Scintillators can be made in different sizes, and the thickness of the scintillator determines its ability to absorb and detect certain radiation emissions. A thin scintillator is an excellent choice for low-energy gamma rays and high-energy beta particles. The ray or particle will be absorbed within the thin scintillator and the light produced by this interaction will be able to pass through the remaining thickness to allow the gamma ray to be detected. A high-energy gamma ray is likely to pass right through the thin scintillator without interacting.
A thick scintillator is the choice for radionuclides emitting high-energy gamma rays. This scintillator is thick enough to absorb the gamma ray but not too thick to prevent the light that is produced from being detected. A thick scintillator is not very good for low-energy gamma rays; they will interact but the scintillator is too thick and will absorb the light that is produced before it can be detected.